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Joined on January 2, 2008

Last Post on December 30, 2013

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Chemical for Cleaning Blocked Boiler heat exchangers?

@ May 1, 2013 11:35 AM in Chemical for Cleaning Blocked Boiler heat exchangers?

Are there any products/chemicals you use that "assist" your manual efforts in the cleaning of blocked cast iron boiler heat exchangers?

Cat 1 vs Cat 3 - benefits to Cat 3?

@ April 25, 2013 3:32 PM in Cat 1 vs Cat 3 - benefits to Cat 3?

Cat 1 appliances are mid efficient non positive vent pressure - non condensing. Cat 3 are mid efficient positive vent pressure, non condensing. If an appliance can run either option (e.g Viessmann Vitorond 200), what benefits are there to running a cat 3 over a cat 1? The only one I now know of is you can run smaller vent sizes on Cat 3 obviously because the positive vent pressure helps push the flue gas out instead of relying on draft to move it. The cat 3 may be slightly safter as it has to be a fully sealed vent where as a Cat 1 in a lot of cases requires some form of draft control (e.g. draft hood, barometric damper) which could spill in some situations. Any other benefits to Cat 3?

Should low temperature protection of Category 1 or 3 appliances be a code requirement?

@ April 15, 2013 4:44 PM in Should low temperature protection of Category 1 or 3 appliances be a code requirement?

When a Category 1 or Category 3 Gas Boiler (typically made with a steel or cast iron heat exchanger designed to run above 140 degrees F) starts up cold it will condense for a period of time.  A little bit of flue gas condensation is not going to kill one of these boilers in most cases, BUT extensive flue gas condensation, especially in systems used in very intermittent situations with large volumes of water that need to be brought up to temperature, will impact the longetivity of one of these boilers negatively, and I would argue in some cases could cause a dangerous situation which could cause flue gas spillage or potential fire.
There are a few different ways to design low temperature protection into the hydronic side to ensure these boilers do not condense - 1) A "Shunt Pump," which bypasses a percentage of the supply water back into the return inlet of the boiler. 2) A 3 way mixing valve which blends some of the supply water back into the return to ensure the boiler return is above 135-140 F 3) Other hydronic designs, for example a primarly secondary system with higher flow rates on the primary side always ensuring some of the supply water is put into the return, etc.
I'm curious why this is not a code requirement, or if it is a code requirement in your area, I'd be interested in hearing what the exact codes or standards are.

Cathodic Protection

@ November 8, 2012 1:01 AM in Cathodic Protection

I'm just curious if you guys can point me towards some information on cathodic protection of underground steel gas lines. Do you know of any manuals or books worth reading on the subject? I'm talking about impressed current methods with respect to ensuring they are functioning properly and doing their job as well. I'm told the Copper Sulphite or Sulphate half cell test is the one we're supposed to use but I haven't done too much digging yet other than a few minor searches online.


@ September 5, 2012 12:04 AM in Leaking HX on Vitodens 200

That's some serious lack of maintenance.

The Coaxial venting system tends to cool the exhaust as it travels outwards and the intake travels inwards also imparting some heat to the incoming intake air which raises combustion efficiency, as many of us all know. Obviously the area where the inner, exhaust pipe connects to the heat exchanger will have the highest temperatures but consider that when the boiler is running there is still a good flow of intake air in that area pictured. For that exhaust pipe to fail like that, even rated at around 230-250 degrees like most polypropylenes are rated for, suggests some SERIOUSLY high exhaust temps. I'm gonna buck a wild guess - AT LEAST 280-300 degrees.

The nice thing about coaxial venting is it is also very safe, especially the way Viessmann does it. In this case, the exhaust leak would be reingested into the intake and not dumped into the space. But this is not something you want occurring on a prolonged basis. As some have pointed out in the past reinvesting exhaust into the intake air will reduce the PH of the condensate even further to the extent that it could due some damage to the stainless and in some cases could cause the boiler to have ignition failures.

Depends on your Chemical Guy

@ August 30, 2012 9:52 PM in best boiler type for 100% makeup water

I would go with an old proven favourite - a Cleaver Brooks Fire Tube Boiler. They are proven in the field with many boilers out I work on that are easily over 40 years old, reliable if maintained reasonably well (you should get at least 50 years out of them if you take care of them), efficient by design (you cant beat the 4 pass design for efficiency - 82-85% efficiency in steam applications typically), easy/cheaper to retube if ever needed compared to water tubes which cost an arm and a leg to repair/retube, and fairly versatile. You can also add several accessories on them to enhance their user friendliness and efficiency, such as the HAWK controller, Oxygen Trim, a High Turn down burner, an economizer, etc. You can outfit this out of hte box, or add them later if you so choose.

As far as longetivity goes the absolute key to any steam boilers longetivity is the following:

1) How do you run the boiler? Is it sized correctly? If you keep it hot all the time and minimize temperature swings and on/off cycles (e.g. expansion/contraction of the metal) where your burner and it's modulation range fits well within the confines of your steam requirements,  this will significantly reduce wear and tear on the vessel (typically), and ignition components.

2) Blowdown Regime - It is imperative that you have a proper control of your TDS (Total Dissolved Solids). This will reduce things like foaming, carryover, etc. Proper water samping will help you establish a blowdown/TDS control regime.

3) Chemical/Water Treatment - This is probably THE MOST important item. Spending the money and building a relationship on a good, reputable, chemical guy, who actually takes pride in what he does, is critical. Following his instructions, is key. What you put into that boiler on the water side, whether you have 100% make up, or 0% make up, is critical, and a water treatment program that eliminates minerals (e.g. scale), oxygen, carbon dioxide, and other impurities will go a long way to the longetivity of the vessel itself. I have seen boilers that are 5-10 years old that look so new inside you could cut out the tubes and resell them right there, and I've seen some 5-10 year old boilers that have pitting, and corrosion. I have heard of 50 year old Cleaver-Brooks boilers that are extremely well maintained in this regard that that looked almost new on the water side due to a proper chemical/water treatment program.  Also, having chemical/water treatment components like water softener and a good D/A  & Feedwater system is important and part of your program.

4) If you don't do the annuals yourself (maybe you're not allowed to or don't feel comfortable - check your local regulations/laws), find a reputable company to do them for you. If you choose a Cleaver-Brooks boiler, many states and provinces have a Cleaver-Brooks representative that typically has a service division that should be able to take care of your boiler to factory specs with factory parts.
There are more Cleaver-Brooks boilers in industrial settings in North America than all other industrial boilers combined. There is a reason for this.

They do now

@ August 16, 2012 11:20 PM in Mod Con Boiler sizing

The "Germans" are feeling the need to introduce some smaller stuff pretty soon. Rumour has it they will introduce in North America a smaller Vitodens in the next year with a plate exchanger and storage tank for DHW (e.g. like the Vitodens 222 accross the pond) with a smaller Inox-Radial heat exchanger and smaller burner that modulates down to something like 16,000-17,000 BTUH or there abouts. They are recognizing the need for these low heat loss structures in green buildings and/or the fact that not everyone in more moderate climates such as in the west coast needs a minimum firing rate that is in the 30,000 BTUH range.
With respect to Delta T's - we have to be careful with too low flow aka high Delta T's because they could cause more laminar flow which would reduce effective heat transfer to the space if they are used on the system side. I think the only place higher Delta T's should be worked with is in high head loss water tube heat exchangers like the Vitodens or Giannoni where you are simply trying to get the heat out of the boiler at higher firing rates to the low loss header where the flows on the system side are more tuned towards the traditional 20 degree delta T in mixing with this water. But this does mean that no matter what the lowest water temp returning to the boiler will be whatever comes out of the system. So whomever is advertising the superiority from a Delta t standpoint of higher Delta T's like 40 degrees is false advertising it if they are advocating this as being more efficient; these 40 degree delta T designs to get the heat to the system need to go 20 degrees higher than whatever you want the system to run at and then you drop a further 20 degrees giving off heat to the system to get your 40 degree difference from return to supply.


@ August 2, 2012 9:10 PM in HX pressure drop: can you explain it to a newbie?

To create flow, pumps create a difference in pressure. So if the static fill pressure in a system is 12 PSI (what you fill your hydronic system up to pressure wise as dictated by your pressure reducing valve), your pump will create "pressure" downstream of it which causes the water to flow. So your circulator turns on and immediately, as an example, increases the pressure downstream of it to say 18 PSI (it has added 6 PSI to the static fill pressure). Since there is 18 PSI downstream of the pump, but still 12 PSI (static fill pressure) upstream of the pump, this 6 PSI difference causes the water to flow as pressure always tries to equalize in a system. The difference in pressure the circulator creates is the driving force towards the flow of water and subsequently the movement of heat from the heat source to the heat emitters and back.
Now the unfortunate thing is we know that we need a certain size boiler to heat a certain size house on design day, and we know that we need to flow a certain amount of water to work with our systems design. Lets say after sizing our system we determine we need 10 gallons per minute flow rate to move the appropriate amount of heat. Unfortunately we can't just go out and buy a 10 GPM pump. It doesn't work that way. Every system is different and has different numbers of fittings, longer or shoter runs of pipe, and different components that the water must move through. And each and everyone of these components and pipe/fittings offers resistance to the flow of water that the pump must overcome. This is called "pressure drop" or "head loss."  If we have a fixed run of piping that is say 100 feet long. that will produce a certain amount of pressure drop this will dissipate the pressure difference the pump has created as water flows. If we add piping or components to this system, the head loss will increase and subsequently the pumps flow rate will be reduced. And this works the other way - reduce head loss, and the flow rate increases.

Some heat exchanger designs, typically water tube style where the water is in tubes that surround a cylindrical burner, have high pressure drops, which means you need more pumping power to get the heat out out of the boiler. Some offer so much resistance that it would be prohibitive to flow above a certain amount of water as the head loss just increases so much at a certain flow rate that it's almost not worth it to pay more money for a larger pump, which in a lot of cases, is a LOT more money, and it uses more power to boot. Instead use certain tactics to work with these heat exchangers to extract that heat out of them to work with the system (such as higher delta T's).

If you are as interested as you say you are in learning about your system I highly recommend you buy and read some of Dan's books (off of this site). They will explain it in a much more reader friendly way than I have, plus he elaborates into other areas so you can help see what your system is doing.
I suggest "Pumping away" and "Primary-Secondary Piping made easy" to get started.

Blowing up a Balloon

@ July 23, 2012 12:46 AM in further explanation of Holohan's demonstration

You ever notice when you are blowing up a balloon you have to give it a good puff to get it started but once you get to a certain point it begins to get little easier to add air? Now why exactly that is no one knows but I guess the point is sometimes things in hydronics and steam sometimes defy our thinking but once you understand what is happening it makes sense.

Interesting Question

@ July 23, 2012 12:42 AM in Hypothetical

What if we took it further.
We if we installed 2 expansion tanks - 1 at the suction side of the circulator, the other at the discharge side. We have a static fill pressure of say 12 PSI just for giggles, we set the SUCTION expansion tank to an air pressure of 24 PSI and the DISCHARGE expansion tank to an air pressure of 12 PSI. Then perhaps add some boiler heat to make things interesting as things expand, etc. . Would flow occur?Not that this would ever happen but.....I guess we could ask hypothetical questions all day. Perhaps someone if they had the time could try it?

DDC (Direct Digital Control) - Training?

@ July 13, 2012 10:39 AM in DDC (Direct Digital Control) - Training?

It seems as a Gas Fitter/Hydronic Tech now a days that some at least basic understanding of DDC is neccessary. How much is yet or how far may be determined in the coming years as things evolve further but I'm curious how much DDC Training or Knowledge you as a contractor/installer have and where you learned it? Any good books to recommend or a course or two that you took that you can suggest?



@ June 24, 2012 1:33 AM in Crown Boiler

Just out of curiousity since you took the time to post - what is Crown doing or offering that distinguishes themselves or makes them stand out in your opinion?


@ June 3, 2012 11:00 PM in Relief Valves

You guys don't terminate your relief valves into a drain if possible?

316 L S/S

@ June 3, 2012 10:36 AM in Heat-Flo vs Superstor

Tanks made out of 316 L Stainless Steel are susceptible to chloride attack (commonly found in many city water treatment programs). If your chlorides are too high in your city water it can lead to a premature death of your 316 L S/S tank. Having said that 3 years is a short life for any tank and you'd have to either have a crapload of chlorides in the water (making me wonder if this tank is being used as a swimming pool heat exchanger), or, perhaps a manufacturing defect (what I'd believe in this case without actually seeing the install or the data), to make a tank fail that soon.
Also, are you sure it's the tank and not a leaking tapping that is working it's way through the insulation to the floor?
The only tanks I would spec are the Bradford White RTV S/S series (made out of 444 stainless steel - 400 series S/S is no where near as susceptible to chlorides as 316 L- practically immune apparently). I've put lots of these tanks into operation and I've seen a couple 6-7 year olds without any issues to date. Or the Viessmann 300 series indirects made out of 316 Ti. These tanks are built to last but they are the best value out there.

Relief Valves

@ June 2, 2012 2:57 AM in Relief Valves
The video above documents a boiler explosion that occured in 2004 at BC Institute of Technology in Burnaby, BC, Canada (not as a result of a relief valve failure per se but I just thought you'd find this interesting). I was approximately 50 yards from that explosion when it occured as a 1st year Plumbing/Gas Fitting Apprentice Student at the time. We were walking back from setting up for a Plumbing Skills competition off campus and we walked in front of the plumbing shop yard which contains a few small buildings, including the buildling that housed this boiler. When we were in front of the yard outside the fence that is when the boiler explosion occured and it sent the roof of the boiler house about 200 feet in the air where it landed in front of the door. My mom who was working in a bulding about 200 yards away says everyone in the building felt the explosion - like an earthquake.
IN the course we took there were all sorts of students doing shop projects and the head instructor for the day decided to blow the bell early for everyone to go get changed out of their coveralls. He said he NEVER blows the bell early. For some reason that day he did, by at least 10 minutes. That saved lives and luckily no one was badly hurt or killed.
I guess the ironic thing is right now I work for a company that works on a lot of boilers like the one pictured that blew up (Cleaver Brooks Industrial Fire Tubes).
Where I live for industrial steam boilers relief valve(s) must be changed annually as part of an annual inspection. Hot Water Industrial/Commercial boilers must have their relief valves changed every 3 years, again, as part of an annual inspection (well, every 3rd annual inspection).
But what about residential? Relief valves come with the boilers - I know that is generally a requirement as the boiler manufacturer must provide you with an appropriately sized relief valve for their boiler. But does anyone change out relief valves on residential equipment on some kind of regular schedule or as part of a service agreement schedule (e.g. every 5 years?)? Do any manufacturers of residential boilers require this as per their instructions that you know about? Anyone have any codes or laws in their area that require this on residential equipment?
I'm just thinking right now of all those boilers out there with steel or cast iron heat exchangers that have non O2 barrier PolyB in them for radiant floors - I wonder how effective those relief valves are when bits of the heat exchanger and piping are floating around in the piping for years on end as oxygen permetes through the pipe walls and rust everything out.

Video on YouTube - Vitodens 100 Combi Plus

@ June 1, 2012 12:14 AM in Combi Boiler Recommendation

Here is a video on YouTube showing the Viessmann Vitodens 100 Combi Plus (no association to the contractor who made the video):
The one thing I like about it is the built in diverting valve which allows you to essentially use the pump in the combi plus unit as either the primary pump in a primary/secondary system when it is not being used to pump through the plate exchanger, or to serve a basic load if the pump has enough flow/head to pump through the boilers heat exchanger and whatever other load you have (which I believe is sort of similar to the old Vitodens 200 6-24C combi but theres was built into the cabient). In a sense you had a smaller heating load, the Combi-Plus system COULD allow you to get away with just one pump for your entire system, AND it'd have a nice, simple, clean aesthetically pleasing appearance in that regard.


@ May 19, 2012 2:45 AM in Lochinvar listens....

I think you mistook what I said and I'm not sure what your intentions are. A lot of early North American Mod-Cons - even a few to this day, including the Knights (WHN, KBN, WBN) pipe the direct vent air directly into the fan, where as boilers like the Viessmann Vitodens, or Buderus GB142's, or the Triangle Tube's pipe the direct vent into the cabinet and let the fan pull air from the cabinet. This is beneficial for several reasons 1) Pre-warms the intake air which slightly increases combustion efficiency 2) Lets the cabinet act as a big slow spot for intake air piping so any debris can settle out 3) Keep the mechanical room cooler as the heat exchanger is not projecting it's heat into the mechanical room but instead using this heat to prewarm the intake air 4) If there was ever a venting leak somewhere in the cabinet from a seal or gasket, or something like that, it would just get reingested instead of spewing out of the cabinet into the boiler room. I fail to see how any of this would compromise reliabliity or durability of the boiler unless you had a major venting leak out of the flue which was causing the boiler to inregest a hell of a lot of it's own flue gas back into the intake.
Since Mod-Cons are mandated in England, you probably have a lot of hack installers who don't neccessarily install them in favourable conditions. Perhaps some of the mod-cons are oversized, or installed in old systems with a lot of debris which can cause premature erosion of gaskets or seals, or things in general aren't set up right. European made heat exchangers which are quite common over here, such as the Giannoni do not have very thick pipe walls in the tubing. I believe 0.7 mm is their thickness compared to the Vitodens which is 1.5 mm. Also, you have A LOT more of them out there due to this law requirement so your sample size to find failures is a lot more common. Perhaps pricing over there is a lot cheaper for new units versus the cost to have a tech replace a gas valve or combustion van, so perhaps more people might opt for the latest and greatest. Who knows the rationale. But since Hydronics over here on our side of the water are a smidgeon of the heating market in all honesty we don't have the scale or sample size for a worthy comparison to write a similar article to the one you read about combi boilers. No one installs combi boilers over here. We want large indirects so we can take long, hot showers.


@ May 18, 2012 1:39 AM in Lochinvar listens....

At least they made a bit more "european" as far as having the direct vent air intake pipe into the cabinet, making the cabinet what appears to be sealed or semi-sealed - and using the cabinet as a big fat spot in the direct vent air intake piping to let dirt settle to the bottom as well as the heat exchanger will pre-heat the intake air instead of their knights where they hard pipe the PVC directly into the fan/venturi where you don't get the benefit of any pre-heating.

I'm not much of a fan of the Giannoni heat exchangers either but they do perform well and are quite compact for what it's worth. It's just their longetivity that is the question for some due to the tube forming characteristics as well as the thickness of the tubing walls. I agree though that it's nice to see some lower turn down boilers. Lochinvar owns that crown now (and has for a while, with their 10,000 to 50,000 Knights, now their smaller 9,000 to 40,000 CADET) as far as having the boiler with the lowest minimum firing rate.

Forced Air/Hydronics

@ May 5, 2012 1:53 AM in Why Is the US Always Last

Plus, the hydronics market here is relatively quite small compared to that in Europe. Damn Furnaces!

Not always debris

@ May 1, 2012 12:52 AM in Weird debris in Lochinvar HX

Unless the debris is fine enough to penetrate the mesh into the combustion process, a lot of stuff just sits in the burner can/cylinder until someone pulls it apart and cleans it at an annual service. I've opened up burner cans with some dead flies in them, perfectly intact - they could have been there for at least a year or so.
Boilers that pipe the direct vent direct into the venturi will see more debris as was mentioned. Those that pipe the air into the cabinet and then the venturi/fan pull their air from the cabinet will have less issues with debris as the interior of the boiler cabinet acts as sort of big settling point and everything falls to the bottom of the cabinet. Boilers like the Viessmann Vitodens or IBC SL20-115 are examples of this.

Last I checked Lochinvar does offer an air filter housing that you can install on your direct vent air intake piping that will significantly reduce debris getting into the combustion process.

Indirect vs output

@ February 3, 2012 1:27 AM in Indirect water heaters

The Viessmann's Vitocells have a very high output coil for the size of tank as do the new Lochinvar Squires - they both heat up very fast.
I'm also partial to the Bradford White RTV series at the moment because I have installed a fair number of them and I've also yet to see or hear of a failure of one. They are 444 stainless steel which handles chlorides better than some 300 series stainless tanks. They produce a Dual Coil Indirect the RTV-75D. Not sure if 75 gallons is too big but this dual coil tank has good output.
I think, could be wrong, but I think AIC's new REX indirect is sort of like a turbomax concept (reverse indirect) but made out of stainless, but I'm still trying to get some product specs on it - just saw some basic pictures and info on their website on it.

Lochinvar knight

@ January 28, 2012 9:02 PM in Need about 18,000 btu's to heat small apartment any ideas.

How about the Lochinvar knight whn05
5 which modulates from 11000 to 55000 input?
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