Heating Help

well, then you are not continually flushing your pipes in the summer when the heat isn't running by running the domestic through them.. I guess you're relying on "pump exercising" to do the job?

Constant circ with injection mix

Circ runs 24/7

The plumbers mission is to \"protect the health of the nation\"

Installing open hydronic/ dhw systems seems to ignore the spirit and intent of the plumbers code. All the various mechanical codes I have worked under are quite clear about backflow protection devices to keep the potable side safe from the heating side. Furthermore heating manufactures go to great lengths and expense to have their equipment listed to ASME. Not many, if any instantantanous heaters have that listing. Swapping simplicity and low up-front cost for integrity and liability seems a foolish way to make a living. I question any licensed, experienced, and insured master plumbers willing to make this compromise, with the almighty buck being the only driving force. Especially when your customers health is at stake :) hot rod To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

EXACTLY!!

Touche' Hot Rod.......couldn't have said it better myself!

Please pay Attention

Guys you are getting a little sidetracked here as I have stated in another thread. The concerns listed above have been addressed with the add on "Heating Box" that is a closed loop system. It recommends the temperature from the on demand heater to be around 180 degrees than it steps it down with the domestic side tempering valve to a range from 110 -155 depending on your requirements. The hydronic side is also completely separated by flat plate heat exchangers. The cross over concern has been addressed,the legionella threat has been addressed (this bacteria is killed at about 132-135 degrees) I am talking about an engineered and currently manufactured add-on device called the "Heating Box" that sits alongside qualified on demand heaters (Rinnai,Takagi,Noritz etc) This thread is another long thread about reluctance to change! Which is good until all your concerns are answered! The add on "Heating Box" addresses all your concerns above. My biggest concern is that the HVAC people will get the jump on this because they are already doing radiant and many have marginal plumbing licenses that will allow them to install these. Rich K. Make Peace your passion !

Hey Rich - If it makes you feel any better, and I hope it does, I checked out the Heating Box immediately after being notified via email of your post. Yeah, this forum topic has been *all over the map* but I don't see it about *reluctance to change* (which is true -damn humans!) so much as *wanting to understand how to avoid Legionella* and understanding what that means to us in terms of design, installation and operation of hot water systems (hydronic, domestic or combined). Its been extremely enlightening! I have a new respect and understanding of that little Legionella critter - it's downright pervasive and almost impossible to eliminate! I'm sure you can appreciate that the Heating Box is something we could make up from off-the-shelf parts. What do you see as the advantages and disadvantages of buying the box versus making the config up yourself (besides labor savings)? I don't know enough yet about the fine details of the Heating Box but my major concern is non-standard or proprietary components or fittings that might prevent me from performing a quick, affordable service call? For example, have you ever used the Infloor Zone Control module (that is no longer made). I've replaced three (about 20 yrs old) in the last month because the mixer failed and the 180F water stressed the thermoplastic body into splitting open, leaking and making porridge out of the gypcrete floor topping! It was fairly expensive to eliminate *this box" and replace it with new mixing valve, pump, valves and thermometers (replacements take up a lot more *Real Estate* than the compact Infloor Zone Control did). Same issue with the Infloor manifold blocks themselves. These, and many more out there, are all being replaced with off-the-shelf brass and copper components. (Note - I personally never liked the use of plastic parts in plumbing - very glad I never * bought into * using any acetal fittings back in the polybutylene days!) Another concern with similar such concepts I've had in the past is that one size doesn't fit all. For example the pressure drop at mid to high flow rates for instant wtr heaters varies a lot. Rinnai is lowest, by far, but Takagi, Rheem, Noritz and others have much, much higher pressure drops. And I can buy a Munchin for about $1,200+ more and get 7 to 11 percent higher efficiency. And Rinnai, while they'll bless its use with a pumped flow going through it, they'll drop the warranty from 10 to 3 years. Your thoughts?

Tank manufacturers

Make tank specifically for heating port take offs. Thses tanks with heat ports are asme. In our code open systems are not banned. Though in Oregon all of our indirects and heat exchangers are required to be double wall and vented. Only three states in the union that I know of go to such an extent to protect the water from cross contamination

Interesting...

I perused the Radiantec website: "Legionella bacteria cannot stand temperatures above 115F" (he had a lower case "o" after the 115 that I removed). That one struck me...others included many general references to heating demands and using HWH's. NOT ONE MENTION OF A PROPER HEATLOSS CALCULATION! (Sorry for the shouting) I put in a system in '98 as my house was being built, and my problems were only in the heating area because - as mentioned earlier - I would never use a combined system. I called several times for advice - on my dime of course - and also was given more narrow plates than what I ordered. They only had one size despite showing two at the time. They also said my cast iron boiler would be fine with non-barrier tubing. They also said I would get plenty of BTU's for my 118,000 heatloss calculation...if actually was about 20% less than that and it STILL couldn't keep up in the three radiant zones and I put in more insulation than they recommended. My tubing was turning a lovely orange color from the O2 eating away at the system, and the mixing valve was after the pumps - as per Radiantec spec - and I don't think my radiant was pulling 10,000 btus from the boiler...for about 2,400 sq. ft. (including a 500 sq.ft. garage slab). I found The Wall after six months of searching for other answers...I was a newbie on the 'net in '99 but it was like a religous experience when I started looking around and getting help. I re-piped my boiler w' primary/secondary, put in a heat exchanger for the radiant loops (an Ergomax for the buffer), a smaller nozzle - but still kept the stack temp. at about 350F, new mixing valve in the right place, and other stuff. My baseboard upstairs always worked pretty well, but that was even better. The radiant was better too, but I still am short in a couple of areas of the house that I was worried about from day one. The output of the radiant is still WAY below what I was told, and I cannot imagine what an older home (remember mine is new and tight) would be like. Enough for today...Go Eagles! Take Care, PJO

PJO's experience

Patrick, Your shouting (all caps) was entirely appropriate in this case. In fact, bold print and italics in addition to all caps would be appropriate if that capability were available! :-) I'm sorry to hear about your bad experiences with Radiantec. My own experiences with them were circa 1981-1986 and were exclusively with a man by the name of Bob Starr, who I'm pretty sure ran the place at the time. Maybe the guy you dealt with was an overcondident newbie? A new owner at Radiantec?......I honestly don't know. At the risk of sounding like I'm making excuses for them (not my intent), I've had similar experiences with some of the finest HVAC (forced air) companies in my area - its had to do with turnover, the fact that supervisors can't oversee everyone all the time, etc. Still, there's NO excuse for the seriously (horrendously!) bad advice and corresponding headaches you encountered. It's just plain wrong - very wrong. At the risk of stating the obvious, a cast iron boiler should never be used in an open system - your orange PEX and boiler disintegration being two bad results (I bet the disintegrating boiler heat exchanger material clogged up a bunch of other small-orifice components as well). A heat loss calculation is the first step for any heating system....only an incompetent, untrained person would say it's not necessary (or, second worst, rely on Btuh per square-foot-based estimates)! Then, mixing valves after the pumps (?!?!?) I'm almost inclined to think you mis-dialed their number and was connected to a home for the criminally insane!?!? I am so sorry to hear about your experience! It's probably too late now, but my inclination would be to send Bob Starr an email (or a phone call) and ask him to review these Wall comments. If nothing else it may help encourage him (or whoever is running the place, if anyone) to keep an eagle eye on any newbies. My experience with them dates back to 15-20 years ago. But I have suggesting them to people since, including right here on The Wall less than a week ago (blushing heavily). I value your comments (and others too) on Radiantec. If it makes you feel any better, and I hope it does, I'm too embarrassed to consider sending anyone to them ever again. :-( For whatever its worth, my sincere condolences on your Radiantec experience - I completely understand why you feel the way you do about them!

What are you implying???

Just wondering what it is that you're implying about the water heater I have in my second home. What does age have to do with it? What does water hardness have to do with it? Did you know that the bacteria responsible for LD is omni present? You are correct in that it is not an "open" space heating system, but it IS an open potable water heating system, same as millions of people throughout this country have. I'm sorry, but it appears that you are trying to pooh pooh my contracting of this deadly disease based on the age and condition of my water heater. Are you serious about wanting to have water samples tested? Are you certain you want to know what's in the water? If it WAS found that the bacteria responsible for LD were present in your combination system, would you change your way of doing business, or will you stand by your position until a lawyer shows up at your door? Allow me to debunk some myths about "protective" actions as it pertains to combination open systems... 1. Flushing. Certain "system" manufacturers claim that due to their required method of plumbing, causing all DHW cold water draws entering the dwelling to enter through the hot water distribution system, that theoretically all bacterium are continuously flushed out of the system. Some systemdesigns I have seen require ALL incoming water to be introduced through this system. This results in hot water being flushed down the toilet, and in some cases out on to the lawn. Neither of which is a wise use of a precious (energy) resource. It may also result in extremely cold floors due to cold water being introduced through the floors before it is brought into the home. In situations whereby they make claims of "free air conditioniing", I would also expect to get free mold growth due to the natural propensity of cold water to cause condensation on the outside of all cold water pipes. As it pertains to flushing, if you and your family leave for vacation at any time of the year, the water lays in the pipes, laying around, feasting on the omni present food source, breathing the O2 through the walls of the tubing, having a good time, multiplying,,, When you and your family return from your trip to Wally World, you have most probably been exposed to numerous virus carrying passengers on the pay per ride germ tube (Air Plane) and your immunity system is fighting that infection. You get home, take a nice hot shower, thereby flushing copious amounts of bacteria into the shower where it enters via the water mist droplets, and breath deep, trying to break up the congestion, thereby deeply inhaling the bacteria ito the deepest recess of your lungs, where it can attack in the form of bacterial pneumonia. You become deathly ill, thinking "It's probably just the flu". Eventually, your lungs degrade to the point that breathing is nearly impossible. You feel like you are drowning and you are constantly coughing so hard that you nearly herniate yourself. If you happen to be lucky enough to have a wife who is as persistent as mine, you force yourself to go to the doctors office, only to be diagnosed as having bacterial pneumonia. When I was told that, I said "As in legionairres disease!?!" to which my MD said, "Most probably, 90 percent of the bacterial pneumonia cases are LD related..." When queried as to why they don't diagnose more cases of LD, the MD said it was easier and faster to treat it than it was to wait for the test confirming LD. In other words, we can give you broad spectrum antibiotics and nip this thing in the bud now, or you can wait an additional 5 days for the test results to come back and take a chance on getting even sicker and possibly dieing from the exposure... 2. Pumps and Timer: Some "system" manufacturers claim that they have a pump timer on the system that keeps the infloor water from becoming stagnant, or that there are pumps which keep the water "fresh"... Although stagnation does enhance the growth of the bacteria, it is not a requirement for the bacteria to flourish. If the timer or pump should break down, the theoretical benefits are gone, and trust me, these components do fail on a regular basis. Essentially, during the summer months, the pump/timer copmbination insures that the bacteria are flushed out of the floor and into the tank where they can be inhaled, as well as providing fresh oxygenated water and food to the bacteria to support its growth. It is my recommendation, as a licensed master plumber charged with protecting the health of the nation that you NOT consider this potentially deadly system. No potential dollar savings on up front system costs is worth the risk of compounded exposure to this known, deadly disease. LD is THE most mis-diagnosed disease in the world, and thousands of people die from it every year under the mask of bacterial pneumonia, don't become a victim yourself. BTW, I am aware of two other people who have contracted LD from systems identical to the system you are considering, both who almost died, but survived and are in the process of converting their sytems to true closed loop systems. There are lawyers involved... I am also aware of two identical senior citizen retirement centers with RFH systems in them, one an open combination system, and the other a conventional closed loop system. The building with the open system has twice as many residents with serious lung ailments, and a continuous entourage of oxygen purveyors coming and going into and out of the open loop building. To boot, their floors go cold every morning when all the residents get up to take their shower. Not many happy campers in that place... And again, there are lawyers involved. If you want to continue promoting this potentially deadly system, that is your perrogative. But given the body of evidence, a person would be a fool to continue down this deadly path, And trust me when I say it is deadly... I damned near died from it. And I WILL do everything within my power to make sure that it ceases to happen to anyone else. Consider this the year of changes. Mark Eatherton

What IS he implying Mark?

Mark, I didn't read EJ Hffmans comment as implying anything derogatory about you but rather properly noting the probable relationship between your water heater and your Legionella. EJ, or anyone else that cares about you, should be praised for bringing this up, not hammered on an unrelated issue to YOUR health. The age and water quality supplied to your water heater is **very** important as it may have everything to do with it! Before I get off subject with open system chatter, please be sure to read the sidenote at the end of this post. I'd like to understand how YOUR hot water system was able to harbor Legionella and almost kill you? Do you have an explanation or possible cause? This issue hasn't been flushed out to my satisfaction but, since learning of what happened to you on this forum, I wanted to know. I have a few ideas that seem to be supported by scientific research on the subject: 1) If your heater was electric, even a higher (140F) water temp setting might not be enough as electric tanks can be much cooler at the bottom of the tank (and still allow Legionella to survive). Interestingly, instantaneous water heaters (the orig subject of this forum) may be a healthier alternative to tank heaters. 2) Tank heaters in general are more likely to harbor Legionella because age, and/or sediment and/or corrosion reduces efficiency, heat transfer, thereby lowering water temp and allowing Legionella to survive! What follows are several quotes to support these points from A Canadian web site I referenced in an earlier post (www.sickkids.ca). But first, it may help to understand who these folks are and ask about credibility (with all due respect to Mark, a Master Plumber, and everyone else in this forum, myself included, we aren't the authorities on this important subject. Maybe these Canadians have done their homework? According to their web site - ** The Hospital for Sick Children (SickKids), affiliated with the University of Toronto, is Canada's most research-intensive hospital and the largest centre dedicated to improving children's health in the country. As innovators in child health, SickKids improves the health of children by integrating care, research and teaching.** Here are some excerpts from their report on this subject - ** The type of water heater and mineral content of the water are also important factors that affect the growth of legionella. 22, 23 In Canada, electric water heaters have been shown to harbour higher concentrations of legionella, compared to gas and oil-fired tanks.24 This is due to the tank design: Cooler water pools at the bottom of electric tanks where mineral deposits also collect, creating a productive breeding ground for legionella. Improvements to water heater design and the use of new technologies, such as on-demand (tank-less) water heating, are needed to better prevent legionella growth in water systems in the future.** ** Tank-less heaters also dramatically reduce the risk of legionella infection from hot water because there is no storage tank to harbour large colonies of the bacteria. ** ** Store high – deliver low: a balanced solution One way to balance these risks is to set hot water tanks at 60C and – through the use of mixing valves or other plumbing devices – ensure that hot water is reduced to a safer 49C before it gets to household taps. This solution is supported by Health Canada18 and Quebec’s National Institute of Public Health. ** ** We also conclude that, for most households, there is minimal disease risk from reducing storage temperature to 49C in water heaters fuelled by oil, gas or propane. For electric water heaters, temperatures within the storage tank can vary widely, resulting in pockets of cooler water that create good conditions for some kinds of bacterial growth, including legionella. Where there is any concern about possible infection, households should reduce scald risk by installing tempering valves or point-of-use devices, instead of lowering the thermostat setting of their water heater. ** Side note: Legionella is an airborne kritter and is killed by high water temperature. Is there any scientific evidence to support the idea that, once killed and the dead-legionella bacteria get stuck in an open system piping network, that they can spring back to life? - Or that they can enter non-oxy barrier PEX tubing (as in open system OR - and this seems important - a PEX DHW system)? I'm not interested in opinions, I'm interested in cold, hard facts supported by science (I don't presume to give or know the answer - I maintain an open mind that it may be possible - I honestly don't know).

boatloads of evidence for those who seek

Too much emphasis on just the point of source (tank) being expressed Ray. There are two more pieces in the potable hot water stream to consider as sites that harbour bacteria: the Distribution Netwrork of piping; and Points of Use (or distall sites, as referred to in medical journals detailing LD cases. Danfoss performed a study years ago to find out why super-heated 180F 15-minute flushes only offer a temporary reduction in culture numbers. They determined that the Legionella bacteria survive - ready for this - in the outer fringes of biofilms in the Distribution Network of piping and recolinate the entire system. You keep asking for proof, yet state that we're not qualified to speak to this issue. The proof is easy to find that details Legionella, their needs, and what constitutes an amplifier for the bugs. An open system, by its very design, is a bacterial amplifier. It simply can't avoid being one & a pretty perfect one at that. Taking the 30-year water heater argument a step farther, let's look at the longevity of plastic tubing & consider the long-term ramifications. As ME noted, lawyers are already involved with a number of cases. Law students are being taught how to prosecute LD cases because they see the looming cases and recognize the lucrative nature. According to Stoudt and Yu, Legionella leave footprints much like our DNA leaves undeniable traces for forensic folks to follow. They claim that if tested within a reasonable time-frame, the LD can be positively traced to its exact source. Two deaths from water heaters in Pittsburgh residences were traced in this manner. As for testing samples submitted by someone who supports the use of open systems? Not interested. Random samples from customers' homes who have open systems - absolutely. But, I'll lay my money on the bet that the open system supporters will absolve their systems of any/all responsibility and blame the water heater.

Conditions surrounding my near death experience and exposure ...

Ray, My scenario was this. I maintain a summer home in the mountains of Colorado. This home has a 30 gallon LP fired DHW tank. I'm in the process of getting ready to build a new retirment home up there, and being the energy conservationist that I am, I had turned the operating temperature of my tank to a low of around 115 to 120 degrees F in an effort to stretch my current tank of propane out over 2 years to avoid having to refill the tank, and having to either pump the tank out prior to moving it, or attempting to move a full tank. During the week, when the place is un-occupied, I was turning the tank to PILOT only to save fuel. Upon return on Fridays, one of the first things that gets done is to fire up the well and water heater. Late this summer, I had gone on a trip to Rhode Island for some training. As usual, the plane was full of people hacking and splooting germs all over the place. I contracted a head/chest cold. While up in the hills, the head/chest cold got the best of me, and I decided to take a nice hot steamy shower to see if I could break up some of the congestion. I had the water in the shower turned to full hot, which was just barely hot enough to generate a mist. While in the shower, I was intentionally doing deep breathing exercises, trying to bust loose the congestion. Shortly thereafter, I came down with what I thought was the flue and damned near died. Simple as all that. Once I put 2 and 2 together, I put energy conservation in the BACK of my mind, and cranked the heater up to kill the bacteria. I still turn it to pilot during the week, but I sanitize thermally when it is on. I think a poerson has to stop, sit back and ask him/herself, "What's in it for these guys (Yates, myself and all the other Legionella warriors) to make them want to fight so hard against these systems? I have no monetary horse in this race, nor do any of the other warriors. I have the health and welfare of my customers in mind. It is not my goal to do things as expensively as I can, heck if someone comes up with a better, more efficient less expensive way of doing things, we'd be FOOLS to not jump on that band wagon... While you're sitting there contemplating that question, you must also ask "Why does their opposition feel so strongly FOR the use of combination open systems?" Quite simply, because they are looking for the cheapest way to perform the same function of delivering heat to maintain reasonable human comfort, and are ignoring the potential health implications in the process. Our job, as the plumbers creedo states, is to protect the health and welfare of the country. And so we will. Through code changes and education. Just like we always have. Unfortunately, this one slipped past the powers that be, but it is never to late to reverse a decision with the AHJ's. And as Paul Harvey sayas, "Now you know the REST of the story..." BTW, I've not fully recovered yet. My lungs are ultra sensitive to environmental dust, and I wheeze like an old steam engine most of the time. I'm just greatful to be alive... ME

Glad you're still with us Mark. Please see my latest reply to Dave Yates - same to you (thank you) for your posts. Open systems aside (I've see the light and it's an oncoming train) some documents I've read (referenced in my previous posts) and conclusions I've made as a result, make it sound nearly if not completely impossible to completely remove Legionella with (really) hot water alone. Be careful out there - sounds like you might still be more sensitive than most to Legionella!

nothing meant by it just facts

Mark I apoligize if you took what I said as anything against you. What I was stating were the facts that you gave me to questions I had asked you. Age has a lot to do with it. Ever swapped out an old heater full of sediment older heaters hold sediment lessing the water temps and provide food and home for bacteria to form. Old heater with a bad dip tube even worse. Water hardness has a lot to due with it Look at the insides of your pipes and back again at harder water will put more minerals in your storage tank and cause more build up and less heat output Water hardness you had answered my questions about your shower head as old and limed up. Well showerheads have to pass certain standards and one of them is how much water vapor they create remember vaporizing LD will get it in your system and a showerhead that has clogging/limed up ports mght create finer mists than it should. It seems everyone is focusing on a certain type of system that shall remain unnamed I don't buy into their design I usually end up on service calls fixing them. 1. Copper is a natural born killer is a false statement and something none of us as plumbers should ever use again. Read dave yates post about biofilms forming inside pipe even he says biofilms form inside copper. How do you slow and stop bio-films constant moving water. I constantly circ my loops every house I do gets hot water recirc also. All water has LD and many more various assortments of nasty little critters why do you think they flush out water through the fire hydrants yearly? I really enjoyed reading your story about the nasty"" As it pertains to flushing, if you and your family leave for vacation at any time of the year, the water lays in the pipes, laying around, feasting on the omni present food source, breathing the O2 through the walls of the tubing, having a good time, multiplying,,, "" this happens in the cold water to in fact LD Colonies can explode during summer months in hosebib lines Shower head risers on shower onlly that trap water especially in in rarely used guest rooms are also a great place. Here is a really good place LD can form that long dead run on the backflowpreventer for your autofill on the boiler I see a lot of evidence to keep my water moving and pasturize it the best I can And yeah I will test water from any open system I have done you want to fly out and make sure I Don't tamper with it call me we can set up a time 503-312-3873 Good luck with the changes I would start with cleaning up the water at the ditribution site.

Bravo!

Dave, I didn't mean to imply people on the post don't know anything about Legionella - I was making the point that scientists studying the issue know more than we do....at least I hope so! I don't think too much emphasis can be placed on the tank. Whether its a sidearm tank in a boiler config or a gas or electric water heater, the tank is the point of entry and that is where the Legionella can be killed if the temperature is high enough. In terms of the distribution system, there is ample evidence to support your statement re Legionella surviving in the biofilm. That's true in both copper and PEX piping systems. Various organizations (ie, Legionella.org, ASHRAE Guideline 12-2000, and more) indicate that running water temperature high enough and long enough to kill Legionella in the tank ** as well as the piping system ** is effective in killing Legionella (depends on a variety of factors as you point out, including the residency time of the high water temperature on the biofilm). Chemical treatments of the distribution system appear to be even more effective if Legionella is already present in the biofilm. If the orgin of the water to a distribution system (ie the water heater) is Legionella-free, and the piping is Legionella-free (it takes some operation time to develop the biofilm - new pipe doesn't have a biofilm) a high water temperature will (eventually) kill the Legionella. And once it is dead, if any new Legionella bacteria is reintroduced by fresh incoming water, it will also be killed by a high water temperature - in the tank, and be unable to enter the distribution system. The only exception to this conclusion I can think of is a configuration where an anti-scald valve introduces cold water to the domestic hot water supply - Legionella would likely survive the mix and end up in the distribution system.... My conclusion is that Legionella killed at the tank cannot then establish itself in the distribution system (except in the case above). Your thoughts? Thanks Dave, I appreciate your experience in this area.

facts need to be straightened

Ray, For starters, the Legionella point of entry is the cold water supply & that's the jump-off point for introduction to a potable water system. Not to digress too far, but this is also why heat pumps that utilize the municipal water system in a real twisted approach for open system construction were shot-down by our local water company. They're not much different than the open systems being promoted in this thread - just using the neighbors' water instead! I wish the tank were the only issue. Sure would make things easier. If a tank were held above 133F throughout its entire cycle and no water could exit prior to a 20-minute contact-time, your point would be much more valid. The reality is that there are multiple cycles where tank temps are substantially below 133F, where the bug first begins dying off, and contact-times are brief before the potable water gets an opportunity to be whisked off to the Distribution System and/or Points of Use - not to mention an open-loop hydronic system where all conditions that present an ideal amplification await the bugs. So, the argument that simply raising the storage temp resolves the issues does not hold water. What chemicals? Chlorine at 2- to 4-PPM (what's seen in municipal systems that utilize Chlorination as the bactracide of choice - a practice that dates to 1918 when Chicago became the first to use Chlorine and Typhoid & Cholera disappeared - almost overnight). Chlorine concentration levels would need to be increased by a factor of 10,000 to effectively treat for Legionella. Chlorine also dissipates as water is heated, so it's pretty much gone in the hot water side of the system. Chlorine Dioxide and copper-silver ionization work well, especially the copper-silver ionization systems as they have a residual kill affect & it's the only system that offers complete eradication. For the average Jane & John Doe, there are no economical, reliable and redily available chemical treatment systems that will put a dent in Legionella bacteria. So, what is available? Hot water pasteurization with a system-wide approach (this includes treating the Distribution Network, constant recirc & Points of Use). While hot water pasteurization with temps elevated to 133F+++, constant recirc and appropriate scald-guard devices will not eradicate Legionella, it will keep colonies at levels low enough to save thousands of lives each year - every year. Aids patients and critical care folks whose immune systems are compromised will still need to avoid use. Again, the Danfoss study clearly demonstrated that high water temps will not eradicate - they only kill off the free-roaming bugs & suppress culture numbers. Biofilms form within weeks/months & plastic piping has been proven to offer a better environment during the so-called clean phase before copper gains a film granting a barrier from direct contact. As noted before - the tank is not an iron-clad barrier that offers any guarantees for blocking the bugs from entry to the potable system and, most certrainly, not blocking bugs from entering the open hydronic system. In the proposal put forth in the Watts film, the Distribution Network is maintained at 133F (or higher) to keep the entire network pasteurized. While this can't prevent biofilm activity, it does ensure free-roaming cultures are kept in check. I am no expert, not by a long shot. However, I don't believe you need be an expert in microbiology to read and comprehend what the experts have said about this bug, the diseases they cause and what's required to foster their growth. On the other hand, I've been a plumber for almost 40-years and have a better understanding of what takes place inside the dynamics of a potable water system than do those same experts. So, armed with what I can understand that they've stated as fact, I can only come to believe certain things regarding their bugs and our plumbing systems. It's simple logic and no one yet has been able to find any credible evidence to the contrary - including me & I've looked for years. I think we spoke a number of years ago on this subject (if memory serves). If so, I was much less sure of my stance regarding this issue then than I am today. Mark's experience is not unique - not by a long shot. What is unique about his LD, is his making what appears to be a full recovery. Many who contract LD never fully regain their health. Somewhere between 3% and 15% (for CAP - Community Acquired Legionella-based Pneumonia. Nosocomial - hospital acquired - LD death rates are much higher.) quit breathing entirely and move to the other side of the lawn. (According to the experts, the numbers are somewhat fuzzy because tissue samples are not regularly cultured.) One other method utilized in Europe: UV steralization, but with a twist. Upstream from the UV, they include ultrasonic bombardment to break up cysts of one-celled critters utilized like a Trojan Horse by Legionella & exposes the bugs that would otherwise get a free-pass while shielded from the UV rays as they floated along. They also include a solenoid valve that snaps closed in the event of a power failure. This is a circular argument. The facts exist to more than adequately support the notion that open systems should be banned to protect the potability of our customers' water and to enhance their prospects for remaining healthy. You, and anyone else who wants to, can choose to ignore the facts and believe whatever fantasies suit your desires - be it free A/C or "enhanced" efficiencies. Meanwhile, we'll be pushing for code changes to restore some common-sense to the installation of potable hot water systems. While we strive for those changes, there will continue to be more than 100,000 hot-water scald cases seeking medical treatment, dozens of hot-water scald deaths and, depending on who you want to believe - from the CDC to any number of other credible sources - somewhere between 4,500 and 35,000 legionella-based deaths acquired from residential potable hot water systems - every year. Sure seems to me that if there is a reasonable, reliable, and relatively innexpensive manner with which we could reduce, to a point where these issues would be virtually eliminated, the existing risks, we'd be fools not to pursue them and do our best to get the codes changed.

Excellent post, Dave. Thank you for taking the time to explain these concepts so well and for remaining patient with me (and others) during the process. I've learned a lot and I'm sure I'm not the only one! We're lucky to have you here.

Internet radiant and Viagra

Every time I open my e-mail box, there are a multitude of spam messages encouraging me to buy their "discount" Viagra. The thought struck me while reading this thread that there is a corelation between Internet sales of radiant systems and the bogus Viagra. It won't matter if either of the products work, the only one getting screwed is the buyer!

You're welcome...

We are here to learn AND educate. One possible thought I've had for possible complete erradication is to have a tank on the inlet to the system that would be chilled to just above freezing. Size this tank such that it would be twice as large as the demand tank. Utilize a water source heat pump to super chill and kill the bacteria on the first tank, and transfer the heat removed from that tank to a preheat tank. This way, little to no energy is wasted, and the bacteria is effectively eliminated. The real question is, is the bacteria killed, or just sent into a chilly dormancy... By the way Ray, tell us a little about your self. You seem to be fairly knowledgeable in the mechanical field. What's your back ground? ME ME

Thanks

I have been very involved with the testing and marketing of this product and concept.It has been a very long and difficult process with good test results. Due to the computer problems I have had the last couple daysI was getting very frustrated.I tried to post at the beginning of this thread with nothing but lost messages.I finally got things working and tried to play catch up with my info. I don't want to be miss understood as I want the scrutiny and input from the professionals that use this website forum. I have come to respect a great many individuals here without even having met them face to face. I would not recommend something after 38 years in the mechanical field if I did not feel it was of value. One of my biggest concerns is that HVAC firms who have taken on radiant will see this as an inroad to getting the domestic water side of things as well. (If they are properly licensed and trained I have no problem with that.) My preference would be for plumbers and radiant contractors to find applications for this before our friendly scorched air rivals do. Test site pictures will be posted shortly. Rich K.

Less Chance!

There is far less chance producing an environment for Legionaire's disease in an instataneous heater than in a tank type heater kept at the recommended 120 temperature. Mark Eatherton posted just several weeks ago about his exposure and subsequent outbreak of Legionaire's disease . You don"t lose efficiency at all as you heat up a smaller amount of water to past 140 degrees and then use cold to temper it! The efficency is relative to the old BTU definition! The heat required to heat 40 gallons of water in lets say a 40 gallon tank far exceeds the small amount in an on demand gas heater. Even heating the water up to 180 degrees and then tempering it back down to 125 is far less costly than heating that forty gallons to 120 degrees! If I had you all in a classroom for an hour I could show you this in that amount of time! I have ran all the numbers and worked with engineers who design and build these units. If all of you are still not convinced that on demand heaters are not feasible, why are all the major water heater manufacturers putting on an instataneous line? It is the same scenario as our car manufactures they are set up for tank type heaters in their manufacturing facilities and don't want to retool or admit to the public yet that tank type heaters are about to become the next dinosaur of the plumbing industry.! Prepare for the change! Rich K.

Wrong Mark

That would be Mark Eatherton that got the bug, not Mark Hunt. I feel fine. Mark H To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

btu's

As Rob said, the only difference is the standby loss. On a good tank-type water heater, the standby loss is minimal. Plus, with an indirect water heater, there is almost no need for service and you have one less heating appliance. If the indirect is connected to a condensing boiler, there is no more efficient way to produce hot water. The marketing for these instantaneous water heaters is misleading at best. Shame on Paul Harvey ;-) Instantaneous water heaters have their place, but they heat no less water than a tank-type heater.

Rich, the only difference between tankless and tank heaters is standby losses. That's it. Once you heat up that "40 gallons", you're heating the same amount of water either way... what is used.. plus whatever is lost in standby for the tank. Don't confuse the issue. Water temperature does affect efficiency, I believe due to the nature of heat transfer. HIgher water temps = higher exhaust temps = less efficiency. Now it may not be a LOT depending on the unit, but it is something. As many of the smart guys around here are using BUFFER TANKS on heating systems, I would say if using a water heater makes sense (because you have a very low load in which a more efficient heat source would not pay for itself) that it's unlikely that an on-demand is a better choice than a tank water heater which has its own buffer already built in. If the load is big enough to make the ODWH operate well, then it's big enough to use a better heat source, IMHO. For domestic usage alone though, I have no problem with tankless units.

Plumdogs point is well taken. Its important to appreciate the instantaneous heaters are designed to heat cold water, not recirc hot water like a boiler does. The best instant Ive found is the Rinnai (Bradford White uses it & calls it an Everhot). If you have a very small heating load (say 30kBtuh or less)the lowest-cost, simplest, most reliable heater is a Bradford White tank heater (energy factor in the 0.62-0.63 range; space heat eff approx 85%). Between 30 and 60 kBtuh the Rinnai 2532 appears to be blessed by the manufacturer but the warranty drops from 10 to 3 yrs (added expansion/contraction on HX due to cycling)...their tech support says its the least worrisome in a (low temp)radiant floor application (120F +/-). It requires a decent sized pump (such as Taco 0013) to get 6-7 gpm (& 60-70 kBtuh). The Takagi, Noritz, Rheem, etc units would need two Taco 0013 pumps in series and you still wouldn't quite achieve the Rinnai's flow rate with only one pump! Seems the only sensible application for these instants would be very small heating loads, in which case I prefer the reliability, simplicity and low-cost of the tank heater. I've used Bradford Whites for dozens of simple combined hydronic radiant systems over the last 20 years (my own home included) and, other than the occasional thermocouple, they last around 15+ years (a little longer, on average, than the tank heater used for DHW alone - a fact established by the industry about a decade ago). WARNING: Having worked extensively with do-it-yourselfer and owner-builder types over the years I am very concerned about them doing these installations safely/properly on there own. Fortunately there are companies that are great at helping these folks - one such company I like very much is here - www.radiantec.com

We've often

used a Noritz for combination service. We used to build our own boiler boards, but we are starting to use the Taco X-Pump Block where single wall heat exchangers (HX) are allowed. The HX in the Noritz is not very restrictive (1.58 gpm @ 10' head) and the Taco 008 circulator in the X-Pump Block has no problem. See photo below.

Delta T,s

Delta T i think is being misunderstood In the systems I design the delta t between the radiant floor supply and radiant return is 10-15 degrees the delta t between the injector line and the radiant floor is 40-50 degrees with a 1/2 line at 1.5 gpm 30,000-40,000 btu/h this fits perfect for the areas we heat. Don't let water go stagnate. better recirc your cold water and use every fixture every day or so.

Andrews point - Drinking Your Hot Water - is very important to consider, so I'm very glad he brought it up. I've heard about Legionella concerns like this for the last 30 yrs and have been told, when attempting to find a record of it in an open radiant loop (or other plumbing/piping system) that no such records exist; it seems to be limited to cooling towers and other (exposed to air) type applications. Nonetheless, I'm VERY interested in ANY documented case(s) in a hydronic application. Because of this concern alone, open-loop radiant circuits should have fresh water moving through whenever DHW is used. This is accomplished by having the incoming cold water circ through the floor before entering the water heater. In this configuration it's really no different than a hot and cold water distribution system in terms of the freshness of the water. What I've wondered about, however, are manufacturers providing a combo tank heater and a fan coil - no water moves through the fan coil during non-heating season. It would seem like this (stagnant) condition would be more of a concern, but, again, the manuf's I've spoken with (ie First Company, Apollo) have told me Legionella isn't a concern in such systems. Sounds like this may be a ripe subject for a new topic post! Anyone know of any Legionella in (water-filled) plumbing systems, combo systems or otherwise? If you have a source please post it. And, again, it should be emphasized (overemphasized perhaps) that open systems have their advantages and disadvantages(some of which have been discussed in these posts). It is my experience that they're an elegantly simple and affordable solution for energy-efficient homes with a not-so-big demand. Is a modulating condensing boiler always the best choice? I don't think so. Why? The analogy I give is to look at two extremes - 1) I have a customer with a small home in the hills of Mexico with very little DHW and even less space heating load (couple days a year they need space heat). Will a mod-con boiler-based system be their best choice or would a simple combo system be more cost-effective? Answer - the mod-con has a much higher LCC in this case - a combo system (or wood heat with seperate tankless DHW, etc) option is the better choice. 2) I have a customer in Lake Tahoe California building a medium sized home for a family of three. Which system now has the lower LCC? Answer - the mod-con. By illustrating the extremes, you can easily imagine there are a lot of cases in between. This is where the detailed LCC calc becomes helpful. If it's a wash I think I'd choose the higher eff mod-con system even though the maint/replace costs will be higher over time. The reason I would choose the higher eff mod-con is because I (personally, professionally) believe the 5% annual fuel inflation we've seen the last 30yrs is too conservative to assume for the next 30yrs - but I continue to use that assumption because to do otherwise is impossible to quantify for any professional (God only knows and he won't tell!) - plus I don't want to sound like a crazed doom and gloomer type! Sensitivity analysis, looking at different rates of fuel inflation, seems to be the most professional approach - then the customer can choose to believe whatever they want and choose their solution accordingly.

Ray I really like your post

You have a great post. I like your thought process.

chris?

first off we should all be asking chris how large is the heatload? then the good reasons why not to use such a unit, such as relative poor efficience.

One of the writer's is quite right about the requirement by Rinnai to use their commercial unit if space heating is involved. Most of the Tankless Water Heater manufacturers have suggested schematics on their sites for combo space heating/domestic water heating. You will find with most of the mid size 180MBH units that you will need to create a "Heating Loop" of 1" Pipe and circulate that loop with a High-Head Bronze 1/6Hp Pump like a Grundfos UP26-99BF. However, I would be hesitant about using one of these units for anything but small heat loads. The designed purpose for these units is domestic water heating, and you are going outside the original design use, as well as adding extra cycles to the normal anticipated use. The jury is still out in North America as to the lifespan of these types of units. Good Luck!

Regarding the Taco pump able to pass 1.58 gpm at 10' head - while that's a reasonable head for, say, a recirc loop we're talking space heating - with a 20F deltaT 1.58 gpm will deliver just 15,800 Btuh. As one of the other posts noted, the instant htr manuf's show schematics where the units are used for space heat or to heat a sidearm tank. Before anyone tries doing either one they need to investige the design requirements - other than what I've already posted earlier, I'd like to comment on the sidearm (storage tank) approach - briefly, and I'll use the (very nice) DHW heater from Noritz as an example - it'll only provide about 50 kBtuh of recovery (a small fraction of its input rating) in heating a sidearm tank and that's using two gigantamundo pumps in series! If heating a lot of hot water efficiently is what the job calls (ie, a restaurant, etc) PLEASE use a boiler!! As another post pointed out, the efficiency of an instant at a small delta T, unlike a boiler, is lower than nameplace. NOTE: I worked with industry and 3rd party test labs in the early 90's creating algorithms for the California code calcs req'd for combination (space & DHW) systems - a tank type heater in a combo system actually has a slightly higher recovery efficiency when it's used for space heating (in addition to DHW) - and it'll last a little longer too. Yeah it suprised me too! So did finding out some tank heaters maintained at 180F (instead of 120-140F) will last a little longer (according to American Appliance their res and commercial units use the same tank body - apparently stuff that lives in 120-140F water and eats tanks can't survive at 180F). On Radiantec I can't say I agree with everything they suggest - for example, the Polaris (despite redesign several years back) still burns out ignitors about every 2-3 years - fortunately we only have a couple installs using them and they're cheap (about $25 material and 10 minutes labor) to fix. What I can say is I've dealt with Radiantec since the early 80's and they've been very helpful to a large number of customers I steered their way. While they're not everything for everyone (who is?) their simple approach (see my earlier post for definition) using an open-loop combination system (with a mid-eff water heater) often has a lower LCC than a boiler-based system. A proper LCC needs to take into account EVERYTHING (initial cost, gas use, electricity use, energy escal. rate, maint/repair/replacement costs and frequencies, etc). Open systems aren't (generally speaking) illegal or improper (although its not hard to make them so!) but the customer needs to realize that, if there's a leak, it's gonna keep-on-a leaking until it's fixed! That beautiful wood floor won't have just a puddle, it'll be a lake! With a closed system, assuming the PR valve's upsteam shutoff valve is off after fill/purge, only a few gallons of water at most is likely to end up on the floor if there is a leak. Boiler-based systems were not the subject of this post - if they were, I'd be ranting and raving on the many blessings of boiler-based systems. Fortunately I think 99.9% of the people frequenting this forum appreciate that, in most cases, a boiler is their best choice. I was merely making the point that there's a niche for instantaneous and mid-eff tank heaters while touching on their limitations. Lastly I have to say I treasure this forum and ALL opinions expressed. This is probably the best place on the web to share and grow from our combined experiences. Thanks to all of you for taking time out of your busy day to help the rest of us evolve!

drinking your radiant floor

Bacteria are a bigger concern than leaks or function of the heating system. Radiant floor temps are ideal for Legionella to thrive.

My Take....

I particularly like the replies of Plumdog and Ray Darby; this is bad territory to enter. Some Internet "Radiant Specialists" will promote these uses, but the longest running one I have seen is 8 years (an Aquastar). There is no free lunch, although there are lunches that are fairly cheap, but they make you ill. I like boilers. To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Nothing seems dumber than replying to my own post, but here goes (blush). I must admit I haven't looked at the Legionella issue for FAR too long - thanks again to Andrew for bringing it up! Check this out: http://en.wikipedia.org/wiki/Legionella Sorry - gotta leave - I'm off to crank up some aquastats really, really high!

I think you'll find some pretty strong disagreement around here about open systems not being improper. it's not always a boiler world, but these days, with energy the way it's been and the way it'll go, and with mod/cons here to stay.. it usually is. When it's not, a dedicated tank water heater, or tank and HE, is a far better idea than an open system. Everything else aside, constant introduction of fresh water into a heating system is bad for performance and longevity in many cases.

I would further refine your estimate; at 30kBTUs/hr, if you have a low temp system AND are in a real heating climate, a mod/con is probably still your best choice. The instantaneous water heaters.. There is one and only one thing they do better than a tank heater in radiant. That is, rapid recovery for mass systems. Which should not be the driving factor behind heat source selection in any system. As you note, a tank water heater will run at a decent, if not impressive efficiency (I personally wouldn't call it more than 80%, but that's me). The instananeous will, on the other hand, rarely achieve its rated 83% in a heating application. The mod/con, on a low temp system... maybe, with a cheap buffer... would achieve low to high 90's. run a degree day analysis and you'll find in most climates with real winters, that will give you a reasonable payback (as well as a better operational characteristic with built in outdoor reset) in all but the smallest of small systems. Or in mild climates. I'm a little stunned at your plug as well.

Is the block a double wall for Cali?

You gotta be kidding?

That company? They've done more harm than good for the radiant industry, in my opinion. An 'approved' open system? Not approved in my book.

Well,

Mark Eatherton recently nearly died from Legionella. Got it from his own shower. You might check with him.

Ray, no one is saying a mod con is the only choice. Water heaters have their place on small loads. What we are saying, is that when using a water heater, it should be dedicated or should use a heat exchanger.... period. This is not a dramatic elevation of cost. It is however a very prudent move for the safety of the inhabitants, the future flexibility of the system, and the longevity of the system. Also, running cold water through the mile of pipe you have in your floors in the summer with no regard for condensation is a recipe for mold growth, yes? Seems like an awful lot of chances to take on a client's home that you are not familiar enough with to say it can be done safely, for a very small benefit. I respect your thought process and you are obviously intelligent, but as far as I'm concerned, that's a poor design decision. One I used to make for myself for long time I might add, but do no longer. It's about more than LCC. It's about making sure the system performs well over time, and about safeguarding the home and occupants as well.

and you have no problem with all that stirred up sediment travelling through your heating system?

More Info. Please....

What is the heatloss of your home? How is the spacing on the radiant tubing? Do you have plates? How much insulation? How many feet of what diameter tubing do you have? Does the fresh water flow through the entire system and then go to your HWH? I have a "modified" (thanks to The Wall) partial Radiantec system...but since I work in the water/wastewater field I NEVER even thought about the open-type of system. We have substantial labs where I work - and they do microbiological tesing all day - and you wouldn't believe what's in the city water. Let that sit for a while and then expose it to your lungs or drink it while in the shower? And on top of that a person in immune deficient? Sorry, but none of my loved ones will risk that while I'm on this side of the grass. I'll post my heating experience with Radiantec after I get a thorough description of your system...how's that? Take Care, PJO

How about a Radiantec System Homeowner's Opinion?

Ray, I'd like to hear from a knowledgeable homeowner who has a Radiantec system as you describe...then I will post my own experience. Fair enough? Take Care, PJO

I appreciate everyone's comments. I'll address both Rob and Patricks questions in this post - Patrick - I've lived in the same home for 25 yrs and for the past 20 yr I've used the open loop water heater system (a Radiantec-style design I designed/installed myself). [note - Radiantec didn't invent this system - there are quite a few that came before and after) My system doesn't have any problems (all I've replaced is a pump and a wtr htr thermocouple)and it works extremely well. I've got dozens just like it with happy customers (thank God, as most of my relatives have one). Please post your own experience(s) with this system config as I'm interested in what might have gone wrong. Rob - No mold growth. Condensation isn't a problem in summer and, if you think about it, if it were, wouldn't all my incoming cold water pipes be dripping with water and mold growth too? Keep in mind the floor surface is not as cold as the incoming water temp and, if it were, I still wouldn't have condensation or mold. Metal frame windows and toilet tanks in homes is where I typically see condensation, but that's in winter. Chilled water cooling of slabs is where the problem you mention typically comes up (or very cold wtr pipe in very humid climate). In terms of cost, adding a heat exchanger, secondary loop pump, flow meters and thermostats, PRV, fill valve, controls, etc is not a small added cost - neither is oxy-diffusion barrier PEX. Of course non-ferros components are more expensive, but component costs overall all far less. My potable-PEX tubing is the same stuff we use in DHW, all components are non-ferros, etc. How would all those extra components be a benefit in my case? I honestly haven't experienced any problems with this system config - at least not yet - but I'm always willing to be educated! I use a lot less electricity by using just one pump too, which is important because I'm striving for a Zero Net Energy Home (solar PV and hydropower render by elec bill close to zero every year, despite driving an electric Ford Ranger PU as my primary mode of transportation - I put about 15k miles/yr on it). Also, my tank heater is preheated by an active solar system with a tank built for the life of the home (polypropylene liner, 3" polyiso insul); turns out this was more cost effective than a higher efficiency heater in my case.

Ray: I have seen open systems clog and corrode in short periods of time. This is not common, but unless you are doing full water quality testing, and you know it's stable, on the homes of your clients, this is dice rolling. I see condensation on cold water plumbing in the summertime all the time up here in maine, which is not arid... nor is most of north america... Luckily, this is a relatively small amount of piping in a home typically. You don't see summer condensation on cold piping? sweating toilets? I'm not saying the floor surfaces should be condensing or crawling with mold.. I'm talking about what's happening around the pipes, say in the joist bays, when you multiply this potential condensation surface area by a factor of, what, 100? Not a problem that would be noticeable for quite awhile perhaps, but certainly one that does not serve the long term interests of the structure nor the occupants. non barrier pipe isn't the greatest idea ever either.. use a cheaper brand of o2 barrier pipe if you really want to save money ;) Obviously you can do it.. and as long as you, or the next owners of the home, don't need antifreeze, it's not a big deal. But o2 penetration can compromise antifreeze products which someone, someday, might need. Given how fast homes "flip" on average, you have to think beyond the current owners too... If you really want to though, nothing says you HAVE to use o2 barrier pipe in your separated system, it'd be open to oxygen, but at least it wouldn't be a "fresh water" system. to make a water heater system closed, you add a heat exchanger, expansion tank, PRV/Fill, and one pump, and that's about it. If you WANT to add a couple hundred to turn the HE pump into an injection pump (and ditch the tempering valve you'd otherwise need unless you're running the water heaters lower than they are supposed to be run) and vastly improve the operation of the radiant in most cases, that's a choice you can make, but you don't have to. Compare that to the cost of the rest of even a cheap radiant system, and while it's noticeable, it's rarely a deal breaker. In your case your heater is backup.. I have no doubt you're right when you say a high eff heater wouldn't make sense for you. Again, no one is saying mod/cons are the only thing that make sense; but when you are servicing a load over 20kbtus/hr in a real heating climate, and it's your primary heat source, it usually DOES make sense. Usually. The issue here is entirely with what an appropriate system design is. Open systems save a small amount of electricity, and a few hundred bucks up front; that's it. In return, you risk compromising the system's operation with the constant introduction of new minerals to react in the system. You risk possible health issues. You reduce the system's flexibility to adapt to the needs of future owners. If HE systems were a LOT more money, maybe I'd consider it more strongly. But frankly Ray, from where I sit it looks like a pretty poor trade for me. A one shot insurance policy of this caliber, at this price, doesn't come along every day.

We've often

used a Noritz for combination service. We used to build our own boiler boards, but we are starting to use the Taco X-Pump Block where single wall heat exchangers (HX) are allowed. The HX in the Noritz is not very restrictive (1.58 gpm @ 10' head) and

Rinnai instant water heater used for heating

Greetings I was wondering if anyone has had any experience used an instant water heater for DHW as well as heating. I imagined it would be possible by creating a loop between the hot and cold and using a stainless steel circulator pumping through a stainless steel heat exchanger. On a call for heat this circulator and one on the other side of the heat exchanger would come on. Water would move through the water heater, through the exchanger and pump and then start over. On a call for DHW, the SS circ would stop, and start again when the call for DHW ended. Any suggestions would be great.

Instantaneous Wtr Htr Space Heating

I've had experience with this subject going back 20 years. In a nutshell, to engineer such a system you need to review the heater manufacturers technical specs. In particular, the pressure drop through the unit at the design input/output temperatures (with most units its pretty high) and the output capacity under those conditions. For example, the Rheem folks don't seem to know (much less have) a flow vs head curve! The Noritz folks (nice unit!) have the curve all right - but upon close inspection it seems the (194k input) unit won't put out more than 55,000 Btuh assuming a 20F delta-t; and that'll take two Taco 0011 pumps in series to get the (approx) 55' of head to pull it off! Kind of excessive pump-wise. I'm checking out the Bradford White Everhot (Rinnai) for lower pressure drop..... Years ago I worked with Aquavac (now defunct) on their instantaneous and learned its possible to decrease the pressure drop through a modulating instantaneous. I'm hoping to "resurrect the dream" with one of today's units. Anyone with more research tidbits to add to this is encouraged to do so. I'll backfill whatever new info I get here on The Wall (isn't this place great!?!?)

bradford and noritz

I use bradford mostly, it is a rinnai with a built in remote control. Noritz is really nice but getting all the parts stocked in my area is difficult. I do constant circ with injection mixing and most of the time all you need is a 006 you have to keep the flow rate just right to keep it from cycling minimum 3/4 gpm on most units. Also i only go with a 15 delta t Most design temps in 108-120 this is only a 2 pump system. Constant circ on the floor loop with the injector pulling off the water heater and getting it to fire. the injector allows you to eliminate the need to keep up the 2gpm flow and with the 3/4 gpm flow the heater usually runs on the lowest fire most often 10000 btu for most heaters I use a tekmar 356 to controll the injector

Internet sales

Guy I know bought a kit off the internet and installed it himself. Takagi water heater, heat exchanger, huge pumps, manifolds, the whole enchilada. He now lives in a cold house with monster gas bills. Wishes he would have got a real boiler.

Perhaps... But usually not

I am a homeowner and not a heating professional. On the other hand I have some experience... Perhaps a "hot water heater" could be used as a stand alone (not for DHW) where there was only a small heating load - say a lot farther south than I live. You would have a separate unit for DHW. While very small boilers can be purchased in Europe (10,000 BTU/Hr) there is nothing like this in the US. In a case with a heat load like this - perhaps your idea has merit. Keep in mind that if you did this - these would be not be expected to necesarily last a long time. But it may be a lot cheaper than installing even the smallest boiler out there - and could be rigged with quick disconnect type fittings (couplings) so that it could be easily replaced. This could not be done if a code stamped home heating boiler was required. However, for larger heat loads - I think you would be best off with a regular boiler. Perry

instant water heaters

Not sure of your layout based on your description but most plumbing codes do not allow mixing heating water with domestic and Rinnai tells us here that if you use on of their continuums for heating you must use the commercial unit or you will void any warranties.

Well, take a look at most radiant systems and differences should be pretty easy to spot ray. it's usually a lot bigger, for one (re the health issue). there are usually a lot more items to potentially gum up and fail, for two, and they are more expensive items as well, and are not generally seen as often as, say, the bathroom sink might be where you would see leaks starting before something bad happens. You'll have less sediment sitting in the tank.. fine. But the same amount of sediment is coming in through the water, and you're circulating it along with whatever mineral content the water heater THROUGH THE HEATING SYSTEM. I suppose in super dumbed down, large diameter PEX systems (which I would also generally oppose for good design reasons), this might be less of an issue. It would take a heck of a lot longer to gum up a 7/8" pipe fitting, leaving just corrosion as a possible issue. But, again, that involves a lot of design tradeoffs that really don't seem to me to be in the client's best interest (wider on centers, higher water temps, to name two).

PJO, My own system is shown in basic schematic format here: http://www.radiantec.com/systems-sources/open-system.php The schematic is a bit oversimplified relative to mine in that it doesn't show multiple circuits, one of which is mixed down (stamped conc floor) and it doesn't show exp tank, thermometers, flow meter, etc. But it gets the point across re fresh water entry. I'm getting ready to leave this post as its transforming from educational to hostile - but I'll check back for your responses on Radiantec (Man oh Man, have they rumpled some feathers out there or what?) From some of the posts its hard to believe they haven't been shut down after ticking so many other installers off over the last 27 years!). I've learned my lesson though - bring up the open combo system and people can get downright crazed! Since they share so much in common with a water heating system using PEX (see my previous posts) I'm wondering how all these peeved off folks have remained calm so long when thinking about standard DHW systems?!?!?

Just finished a 5300 sq ft ranch post and beam

the water pipe potable just the hot side was 1200 ft with a recirc on it it looked like a suspened tube radiant system ho put in forced air furnace

It might be easier to digest the sediment issue (pun intended) if we consider a standard DHW heater. Every time its used, fresh, mineral laden water enters. A small amount typically settles in the tank each time, building up over time. The manuf's are using swirly-tubes to stir it up so it doesn't build up over time. The cold incoming water is what swirls it up, then it comes out your hot water faucet.

...provided it doesn't get stuck in all those nice mineral deposits building up in your heating system as it circulates, waiting for the next DHW demand to flush it out and bring in more ;) Seriously Ray, it's not very common, but I have seen systems gum up from this. The first time you have a client have to abandon the system your company provided for them, you might wonder how happy they are about that few hundred they saved up front. With my previous employer, that was what made me realize that maybe the wisdom of that course of action was questionable. I only fielded a couple of calls like that... I have no idea how many more may be out there that were with second owners who didn't know the company... But even a couple was enough for me to think "not worth it". That's a truly major disaster when it happens. Again, it's cheap insurance to use a HE, even without any potential health concerns at all.

I appreciate what you're saying about the gumming up issue. The first thing I thought of after reading your post is I see the gunk inside old faucets. I changed one recently in a (standard) DHW system and it was absolutely disgusting to think about the occupants drinking the water that has been flowing through that gunk all these years! That's one reason why I like PEX for hot/cold plumbing (I'll probably get beat up on that statement too, but I'm getting used to it), especially after seeing what CU pipe looks like in most DHW systems after 15-20 years, especially with poor water quality. In a combo system, as long as my (relatively few) parts are brass and CU, if they get gunked up at some point I'll simply replace them (just like I'll need to do with my hot/cold water plumbing).

why wider spacing?

why wider spacing. I use 1/2 inch but I use constant circ on the radiant water doesn't have a chance to sit and grow bacteria or collect deposits 7/8 tube could still be put on 6-12 spacing and then lower your water temp just design for what spacing you want some use 7/8 tube to cheapen a system I don't play that game I design for comfort and effeciency not for cheap to compete

Sure, at a cost probably similar to doing an HE in the first place ;) What happens if that gunk is caustic to your system and causes a real integrity failure? Brass and CU can corrode under the right conditions as well (they are non-ferrous, not invulnerable).. one of those conditions being the application of a catalyst such as heat, yes? Again, this isn't common. When it's your house, you can keep an eye on things. What I'm saying is when you are designing for homes in radically different locations, you cannot be aware of the factors on the ground to the same degree you *MIGHT* able to in your own home. As such, you're gambling.

I guess I'm still strugling with the idea that an open loop combined HRF is significantly different than a DHW system with copper and brass fittings. The main difference is longer (PEX) pipe runs, but I'm not concerned about degradation of the PEX (or sediment in the PEX) like I am with the CU and brass parts. The reason I was given by WH manuf's for tanks lasting longer in a open combo system is because the sediment is stirred up a little more than with DHW alone. It seems reasonable therefore to assume a combo system will have *less* sediment than a standard DHW system, not more, and the parts within will get less gunked up.

well, dave yates hasn't ;) for my point of view though, for the health issue, just do a little math. Compare surface area within the heating system pipes to surface area in a DHW system's pipes.. compare that ratio to the amount of water.. then think "concentration levels".

ROCHESTER, N.Y. Rochester's largest hospital is dealing with its third case of a patient with Legionnaires' disease. The case was announced yesterday -- two days after another patient died, with the disease partly to blame. The bacteria that causes the pneumonia like illness was found in Strong Memorial Hospital's water supply on February 13th. About 500 patients have been on bottled water since then as the hospital cleans the system. The disease kills about 10 percent of people hospitalized with it, but people with weakened immune systems are two or three times more likely to die. That's according to the Centers for Disease Control. Two cancer patients have Legionnaires'. One is in guarded condition, and the other is satisfactory. A third patient with hepatitis died Sunday. Legionnaires' infects fewer than 100 people in New York each year. This was found in the drinking water system. Now imagine standing in a shower with tepid water misting you that is heated with a combi unit that is shared with a heating system with out a isolating heat exchanger?? NOW THATS THE MAKING OF A LEGIONAIRES BREATHING CHAMBER

It's extremely serious all right!! After doing some research I found MANY similar stories, mostly in institutional settings such as your example. The solution typically offered is to set the water heater at 140F (or higher) and use an anti-scald valve. If there's any comforting news in all this its this (from pg 12 of Government report, citation follows): What does real-world experience tell us? While it is recognized that legionnaires’ disease is under-reported, experience in the United States is encouraging. For over a decade, local laws and nation-wide industry practice in the US have required that water heaters be installed with the thermostat set at 49°C in order to prevent scalds. Yet the Centers for Disease Control has not reported a significant increase in cases of legionnaires’ disease, a reportable condition, during this period. The state of Washington has been practising reduced thermostat settings by state law since 1985, and the rate of legionnaires’ disease in that state is similar to the national average. The full report is here: http://www.sickkids.ca/SKCPublicPolicyAdvocacy/custom/TapwaterscaldsDISCUSSIONPAPERrevised2005.pdf

lots more to do Ray

Go look up bacterial "amplifiers + water heaters" too. Cooling towers take the heat, but where do they get their water? Wikipedia as a resource? Isn't that the so-called "encyclopedia" that allows folks to post changes? Look up the conditions that give Legionella exactly what they need to thrive while you're at it & then explain how an open system avoids meeting all of those conditions & tell me why it shouldn't be labeled an "ideal amplifier". Check for Ph, water temps, food sources, and that old reliable - stagnation. Find out if all four must be present at the same time while you're at it. Look up "Legionella - The Coming of the Third Plague" on Google. You have a long way to go and a lot to learn. To assume open systems are safe simply because no credible scientific study has ever been performed to test for Legionella Sero Group #1, is an astounding leap of judgment for making the claim that they are, therefore, safe. Since you evidently feel that open systems must be safe simply because you never got sick, look up just who might be at risk and what varying levels of wellness may have to do with this issue. You might ask Mark Eatherton about water heaters and LD too. He's had a little experience. To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Thank you Dave, I did just what you suggested (googled Legionella - The Coming of the Third Plague). And I'll continue to educate myself on this important issue. I'm sorry you don't sense my concern for Legionella - text alone doesn't always carry the full message. I am VERY concerned about public health as I hope we all are.

Swimming pools

Swimming pools are responsible for more deaths than legionaires disease.

Have not found 1 case linked to an open system

Dave, You may not have caught my last post. My understanding (please correct if I'm mistaken) is that Legionella is best controlled by setting the water heater to 140F or higher. Whether its an open hydronic (with fresh water introduced) or a simple DHW system, it seems to me the water heater setting takes care of it. It seems to me the hydronic distrib system is no different than a PEX-based DHW system - both are open systems with hot and cold running water flowing through them. Therefore wouldn't a hot and cold water PEX distribution system suffer from the exact same risks? Why wouldn't a higher hot water storage temperature, as recommended by health org's, do the trick?

He did not have an open heat system

Mark did not have an open heat system he had a 20 year old 30 gallon tank with hard well water and a limed up shower head. How about testing some water from open systems I send anybody some samples

I see what you're saying, and I'm sure you have a good point there. But, why would I want to have to run a heat source 30 to 60 degrees higher than I need to heat the home? does that strike you as particularly efficient?

You're right, Rob, running a heat source at 30-60 degrees higher than necessary to heat the home (like say a radiant loop that needs 110F water) isn't efficient at all! Efficiency guidelines have for years been telling us to set our water heater at 120F. Legionella bateria are the reason given to run 140 or higher in DHW heaters which then requires a anti-scald valve for safety. Maybe UPC should require water heaters be (literally)unable to be set below 140 and require anti-scald for the whole hot water distrib system (instead of just showers,etc).

Again, Dave would say yes. I'm not sold on that yet... but there is a big difference between a storage tank and 50 feet of hot water pipe, and a couple thousand feet pex PLUS a storage tank and 50 feet of hot water pipe, in my mind.

per reccomendations from here

we put mixers on water heaters and turn our heaters up to 140 just for the potable so instead of two appliances we have just one

Legionaires from Plumbing?

You betcha! Read below!

they kill more kids than guns too... so it's ok to leave a loaded handgun on the table when you go to work?

Heating flushes the tank more

less sediment build up less chance of growth in your pipes moving water many open systems are turned up max temps also

Less sediment? Huh. where does it go? Less chance, sure, if you run higher temps in the system, while you are heating. This isn't a death sentance. Just not a good idea. I don't know about you, but I design low temp systems anyway, so the client can do things like use solar later on. If you're running the water heater at max temps (140, I presume) then other design decisions should, IMHO, be questioned.

What are you sayng about max temps?

I don't design for 140 in the floor more like 100-110 un less it is hydro air. But per recomendations a water heater at 140-160 with a mixer kills legionella after 20 minutes.

Actually...

Using it for heting would cause more sediment...especially if you have well water. More fresh water flow through the system and then it gets heated = more sediment. What is "Hoffman Hydro"? Take Care, PJO

Dip tube

Dip tubes in water heaters do two things cold to the bottom and stir/suspend particles Sediment goes out the faucet Radiant heat company and plumbing compny is what Hoffman Hydronic and Plumbing is.

On Demand Heater as Heat Source

It is being done already, there will be a system on display at the AHR show in Dallas.(January 29-31) Look for the Navien America Booth. I have ran two test installations for them here in Wisconsin. They work great! One with a Rinnai unit and one with a Takagi. Contact me for details Rich Kontny