The Wall
Forum / Radiant Heating / Need some serious help
  • Post a Reply to this Thread

    Need some serious help (38 Posts)

  • Nasdaqsam Nasdaqsam @ 10:24 AM
    Contact this user

    Need some serious help

    For a little background. This is a new system in a new 3400 sq. f.t super insulated home located in upstate NY. I know just enough about heating systems to be dangerous so have to keep this in laymans terms. There is no issue with the system heating the house it handles that with ease and trust me this it is getting tested it's been a very cold winter so far with significant winds from the north. This house is set on a lake and takes full north winds with no break for miles. I am very impressed with the heating. If a few people are working the temp will come up 2 to 3 degrees above the thermostat.

    The system: The largest Buderus GB they build I think it is a 160. 4 zone system, hot water is handled through an on demand so not off the boiler. One zone is baseboard radiation this is for the 2nd floor, the other three are ground floor with in floor. One for the entire 1st floor, one for the garage and one for a snow melt system in the driveway. The snow melt is another whole issue in itself but for now thats not a priority so I am not using it.

    The idea when building the system was. Fire the boiler at 185 to run the baseboard loop then use mixing valves to temper it for the in floor. First, can this be done or more importantly should it be done?

    What I am having a problem with is tempering the water to the in floor. The mixing valves do not seem to be able to cool it enough for the infloor. If we turn them all the way to full mix it all but stops the GPM. It is coming in at the 185 and we can only get it down to 160. The GPM is running .6 to .75 but touch the mixer and it all but stops.

    I know your going to need more info and I will have to get whatever you need so please ask.

    Thanks in advance
  • SWEI SWEI @ 10:37 AM
    Contact this user

    FIrst things first

    Did anyone perform a heat loss calculation on the house?  What was that number?

    If this is "the largest GB" is it a GB162/100 or a BB142/60?

    Firing the baseboard at 185 should only happen on a design day if the boiler is correctly installed and commissioned using the outdoor sensor.  The mixing valve for the other zone should be motorized and under separate outdoor reset control.
  • Nasdaqsam Nasdaqsam @ 10:51 AM
    Contact this user


    There may have been one done but I do not have it.


    The installer did not add the outdoor sensor he has the boiler temp set at 185.
  • SWEI SWEI @ 11:03 AM
    Contact this user

    Heat Loss calculation

    Is not all that hard to do yourself. will help.

    At 52 BTUs per square foot the boiler is seriously oversized.  If the installer did not install the outdoor sensor, he did not do his job.

    I'm guessing there is probably more that is wrong based on the preceding two issues.  When was this system installed?
    This post was edited by an admin on January 30, 2014 11:08 AM.
  • Nasdaqsam Nasdaqsam @ 11:12 AM
    Contact this user

    heat loss

    I will work on the heat loss and get that posted.

    No doubt the installer did not do a full job but it didn't start out that way it was a series of circumstances that created it. That really is all behind me so I have to focus on fixing it.

    The home is a 3400 sq. f.t two story located on a northern exposure bay on Lake Champlain. There is literally nothing stopping the north winds between me and Canada so she takes a beating in the winter.

    It has spray on insulation. Closed and open cell as needed where needed. The roof has 4" of closed then 6" of open. The wall facing north is 2" of closed with 3" of open and so on. Like I said just a few guys working in the home can bring the temp up a few degrees on a below zero day. The reason for the larger boiler was the snow melt system. Not sure if that is a valid reason or not but we didn't want to be undersized.

    I am hoping with some help here I can slowly make somes changes and make what I have work.

    I am going to install the outside sensor tonight if I can figure that out. It is out there and the wire run in just not run from the controller to the boiler yet.

    Forgot to add. It was installed this past fall but not completely. The boiler was up and running with the house loops running. The garage and snow melt were just hooked up recently. The snowmelt is on hold until after I fix what I have now.
    This post was edited by an admin on January 30, 2014 11:15 AM.
  • SWEI SWEI @ 11:18 AM
    Contact this user

    The snowmelt system

    Needs its own load calculation.  There should be a separate controller for that, perhaps a Tekmar or Uponor box?  How often does it get used?

    Given the house construction, I would probably have installed separate boilers for the house and snowmelt.  Are you on natural gas or LPG there?  What are your gas and electric costs?
  • Nasdaqsam Nasdaqsam @ 11:26 AM
    Contact this user

    snow melt

    The snow melt as of now has never been used. My intentions are going to be to use it as needed or manual for now and maybe automatic in the future.

    Electirc is .14 and Propane is 1.79/gallon on contract. We do have a good possibility of natural in the very near future.

    The drivewas installed as follows. 24" of item 4 gravel compacted, uponor insulated panels with 1/2 pex run at 12" spacing with 2" rigid run along the perimeter then 1" of sand and then pavers . It is 24' wide and 24' long. The lines run through the heated garage floor so get some pre-heating. I do have the Tekmar 665 controller but have yet to pick up the 090 sensor.
    This post was edited by an admin on January 30, 2014 11:30 AM.
  • SWEI SWEI @ 11:35 AM
    Contact this user

    Let's see what the heat loss calc says

    I suspect that your design-day heat loss will be less than the minimum firing your boiler is capable of.

    While you could install a buffer tank and additional controls to mitigate this, the cost to install a new, properly sized boiler may not be a whole lot higher -- and the results for both comfort and efficiency will be far better.  I would probably dedicate the GB142 to snowmelt.
  • Nasdaqsam Nasdaqsam @ 12:00 PM
    Contact this user

    heat loss

    I'm afraid I do not have the ability to fill out the required info. Cold partition lenght and factors is greek to me.

    Edit I am figuring the heat loss out. just going to take me some time its a big house
    This post was edited by an admin on January 30, 2014 12:05 PM.
  • Nasdaqsam Nasdaqsam @ 12:39 PM
    Contact this user

    boiler size update

    I just went home to double check the boiler size. I was in error it is actually a 142/45

    Sorry about that. I am still working on the heat loss.
  • Nasdaqsam Nasdaqsam @ 1:22 PM
    Contact this user

    Heat loss

    Again the boiler is a 142/45

    First time doing a heat loss but I come up with 124400 including the garage. Not the driveway.

    Sound about right?
  • SWEI SWEI @ 3:18 PM
    Contact this user

    36.6 BTUs per square foot

    is about right for a 1930s-1940s house.

    What's your outdoor design temp there?  Are you keeping the garage at 68ºF and opening the door all the time?
  • Nasdaqsam Nasdaqsam @ 3:24 PM
    Contact this user


    I've never done a calc before so I plugged in outside temp of 0 inside 67. I am in Plattsburgh, NY Clinton County. I did a quick search but could not find an outside design time to work from.

    The garage I keep at 64. It will open and close for the most part twice a day. I most have filled something out wrong. This one is a little tough because the values they give for ratings do not really fit what is built.
  • JeffM JeffM @ 3:31 PM
    Contact this user


    Can you take a photo of the mixing valve and surrounding piping and post it here? From the sound of your first post (flow decreases if the mixed temp turned down), I almost wonder if there isn't enough (or any) circulation on the mixed temp side of the valves. You can certainly use mixing valves to control a lower water temp to the tubing in the floors, but you will need to have that piped and circulated properly for it to work. We can't really tell if that has been done without a photo of the system, or a more detailed description.
  • Nasdaqsam Nasdaqsam @ 3:34 PM
    Contact this user


    I will take a few pictures of it tonight but the piping is very compact so its going to be a little hard to see. I can always take the pictures and answer questions.

  • Ironman Ironman @ 9:35 PM
    Contact this user

    In floor radiant

    Is the floor a slab or wood framed? Or a mixture of both?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Nasdaqsam Nasdaqsam @ 7:10 AM
    Contact this user


    1st floor is slab keyed into a full 8' footer with 2" rigid around the entire inside and a 1" thermo break where the slab meets the wall. The second floor is all wood truss ploor.
  • Nasdaqsam Nasdaqsam @ 7:20 AM
    Contact this user


    It is a very compact system so might be tough to see how the piping is run. As a note I willbe away from my computer until tonight or Sunday so please ask away and I will reply first chance I get. Thanks for all the assistancve.
  • Harvey Ramer Harvey Ramer @ 8:28 AM
    Contact this user

    It looks

    like someone tried to do something here that they don't have enough knowledge or experience for.

    Best thing is to break out the sawza and cut away that tangled hunk of pipes. Have it replumbed according to the time proven methods we all know work.

  • Jean-David Beyer Jean-David Beyer @ 10:03 AM
    Contact this user

    Have it replumbed according to the time proven methods we all know work.

    Do you mean like reading the I&M manual?

    It seems to me as a homeowner that too many contractors hate to spoil that nice plastic film wrapper on the manuals, and it is a matter of professional pride to never look at one. I cannot imagine why that is. I am not prejudiced enough to assume that heating contractors are more dislexic than those in other professions, because other professions seem to suffer from this problem too.

    When I got a new washing machine, that contractor did not even leave me the manual. Luckily, I found one on the Internet. I guess they figure the homeowner does not read the manuals either. Same thing happens with computers. I think too many people are functionally illiterate. They can pass enough tests to get out of 8th grade, but they cannot read an instruction booklet, or at least, they refuse to.

  • Ironman Ironman @ 11:22 AM
    Contact this user


    All too often.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Nasdaqsam Nasdaqsam @ 8:49 PM
    Contact this user


    Anyone around here was capable of that it wouldn't look like it does but thanks for the reply.
  • Rich Rich @ 11:25 AM
    Contact this user

    M A S S

    is what this system requires .  The low loss header must be removed and substituted with a buffer tank . I'll bet that at other than the most extreme low outdoor temps this boiler short cycles .  Your mixing valve problem has to do with the fact that the circs MUST BE LOCATED within the mixed loop , you are pushing hot boiler water through them . With the pumps within the loop the valve is enabled to pull both hot supply AND cooler return water .
       Go to Caleffi website . Scroll down to Idronics 14 , just released . Download and view page 41 , figure 7-14 . This is what your system should look like with the exception that there are no mixing devices shown . But they should be under the circ and connected to the returns accordingly .
    What is your thought on this Pros ?   Judging by your name I can guess that you understand that you can only get a return on a sound investment .  It is time to remake your portfolio my friend
    You didn't get what you didn't pay for and it will never be what you thought it would
    This post was edited by an admin on January 31, 2014 11:30 AM.
  • Nasdaqsam Nasdaqsam @ 8:52 PM
    Contact this user


    Downloaded the manual and will spend some time with it but looks more like a manual designed for heating knowledgable people which I'm not. Crappy situation to be in but it is what it is. Thanks
  • Rich Rich @ 11:26 AM
    Contact this user


    BTU requirement of smallest zone at design conditions so we may inform you what size your tank should be
    You didn't get what you didn't pay for and it will never be what you thought it would
  • Ironman Ironman @ 12:13 PM
    Contact this user

    That bird ain't gonna fly!

    You are going to need a complete re piping after someone properly designs your system.

    One of the major problems you have with the floors is the locations of the circulators in regards to the mixing valves: the circulators MUST draw from the mixed port on the valve, not pump into the hot port. The way it is now, flow will begin to cease as the valve nears its set point.

    That brings up another issue: a thermostatic mixing valve is the wrong component for attempting control of water temp in a radiant slab. The slab is high mass which means it takes a long time to heat up and a long time to emit that heat. It's called the flywheel effect. What that equates to practically is this: the slab absorbs heat for hours at a water temp that's too high because it's controlled by a fixed temp mixing valve - a "dumb" control. The zone thermostat will finally satisfy turning of the circulator, but the the slab will continue to give off heat for hours because of its mass. Now the zone over-heats even though no heat is being sent to it by the system.

    The proper way to control slab temp is with outdoor reset which when properly adjusted will send just the right water temp to match the load. Since you already have high temp BB connected to the system, the boiler's reset curve must be set for that; and that's way too hot for the slab. A secondary reset control is necessary for the slab with a different curve. There are two options: a smart mixing valve or variable speed injection mixing. The latter is the better approach. When that reset curve is plotted properly, a thermostat becomes virtually unnecessary. The curve will keep the slab at just the right temp to match the load. I've got one running that way next door. There's no thermostat on it and it's kept the structure at 68* all season. But, I will eventually put a thermostat on it to act as a high limit.

    You said you domestic is done by an on-demand water heater. What are the lines going to that are hooked to boiler manifold above the low loss header? They are intended for connection of an indirect water heater. If the snow melt is connected there, then great care must be given to sizing the circulator properly to assure proper flow through the boiler. This requires hydronic expertise and given the fact that your installer didn't know how to place the circ's in relation to the mixing valves, I doubt he knew anything about this.

    Again, the best thing you can do is get someone competent in hydronics to design your system and rebuild it from there. Proper design is the foundation that everything is built upon. No one would build a structure without a good foundation, yet in hydronics so many think a good foundation is not necessary. Unfortunately, you're discovering that's not true.

    Several of the pros on here offer design service and consulting if you want it.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Nasdaqsam Nasdaqsam @ 9:04 PM
    Contact this user

    On demand

    To answer this question. The on demand domestic is 100% independent from the boiler. The piping from the boiler intended for the hwt is running the 2nd floor hwbb registers. Can I assume this is a mistake also?
  • Ironman Ironman @ 11:53 PM
    Contact this user

    Most Likely, But Maybe Not

    The black rectangular box that's below the boiler is called a low loss header(LLH). Its purpose is to provide hydraulic separation between the boiler and the system. What that simply means is two different circuits can mix together in there while maintaining their own separate identities. In other words, the flow rate (gpm) of one circuit doesn't effect the flow rate of the other.

    The boiler heats the water instantaneously as it passes through it, there's no storage. This necessitates that a constant flow of water (gpm) be going through it as it fires. If the flow (gpm) isn't correct, the boiler can over-heat it and cause it to instantly flash to steam - not a pretty site.

    If the LLH is bypassed, then the circulator MUST be sized for the pressure drop through the boiler and the required gpm of it, as well as that of the circuit connected to it. There can only be one circuit and one circulator with no zone valves, mixing devices or anything that would cause variation in the flow through the boiler. This is often difficult or impossible to achieve.

    The LLH allows two different circuits to pump through it at different gpm without interfering with one another. The heat is transferred between each other, but each maintains its own flow rate.

    The boiler is looking for 12-16 gpm to always be pumped through it while firing. The system may only have one circ running which is moving 4 gpm - no problem. The LLH allows this. If another circ kicks on and adds 4 gpm more - no problem. The LLH accommodates this and the boiler circuit is still getting the same 16 gpm through it.

    Now, if you don't have the LLH to provide hydraulic separation and you connect directly to the boiler, what happens when the flow rate changes in the system? It changes in the boiler also which would cause serious issues and eventual boiler failure.

    So, to answer your question: if the circulator is properly sized for the flow requirements of BOTH the BOILER and the BB loop; and if there's nothing in the circuit that could cause variation in the flow, then yes it will work. But, I seriously doubt that your BB loop can handle 12-16 gpm. That's about 120-160k btu's depending on the delta T. A 3/4" pipe will carry about 4 gpm and a 1" pipe will carry about 8 gpm. You would need a 1 1/4" line to the BB to carry the flow requirements of the boiler if you bypass the LLH as has been done.

    Another issue also exists: you cannot run the BB circ and the boiler circ at the same time with this configuration as that will greatly effect the flow rate through the boiler. So, you would have to set it up so that either the floors get heat or the BB gets it, but not both at the same time.

    Sorry, but this needs changing too.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Nasdaqsam Nasdaqsam @ 6:59 AM
    Contact this user


    Basically everything has to come after the LLH. He is running bb circuit with a taco 0015 but doesn't sound like that matters.

    I'm going to have to figure out how to get this system designed hopefully using as much of the existing pieces as possible.

    I am limited on time today but will look at Sunday.

    Thanks for the help
  • Ironman Ironman @ 9:37 AM
    Contact this user

    Connection to Manifold

    You may be able to use those connections on the manifold to go directly to a heat exchanger for the snow melt system. Same rules would apply: properly sized circ, no variation in flow, etc.

    You'll spend more time and money trying to use what's there than doing sawzall surgery on the near boiler piping and starting over.

    Again, I'd highly recommend getting a pro to design it for you and then follow his instructions exactly.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Rich Rich @ 12:22 PM
    Contact this user


    is 100% correct .  That slab should employ outdoor reset . Without getting control crazy a Taco I Series ODR mixing device would be a good choice .
    You didn't get what you didn't pay for and it will never be what you thought it would
  • Nasdaqsam Nasdaqsam @ 8:48 PM
    Contact this user


    Of good advise some of which is over my head. So first, no one a have spoken to in this area is capable of designing a system like this, so this is going to a DIY project. But since it is way too cold up here for another 3 months to completely cut out all the piping I'm going to have to figure out an alternate solution. Not sure what that is yet. This sure is a mess and not what I needed to hear on top of some health news I didn't need but the system is a mess and needs to be fixed whatever that takes. I will try to answer some questions asked but please bare with me I don't know the terminology or how to come up with most of the calculations. Thanks everyone.
  • Nasdaqsam Nasdaqsam @ 9:23 PM
    Contact this user


    Regarding the thermo on tank. I can run the hwbb registers off the boiler before it gets to the tank. The tank fits the needs of the main house floor and garage floor But in reading some on the snowmelt system it has been suggested that this zone should run slightly hotter. How is this accomplished? I'm not trying to get ahead of myself I'm just trying to preempt another issue.
  • Nasdaqsam Nasdaqsam @ 8:20 PM
    Contact this user


    Ok I give. I started a new thread asking a pros assistance. Hopefully someone replays and can help.

    As I break down the system it seems the various required zone temps may be the biggest challenge.
  • Paul Pollets Paul Pollets @ 1:33 PM
    Contact this user

    Design and installation

    There are a number of serious piping errors in the "near-boiler" piping that create "choke points" for the BTU's trying to make their way to the heat emitters. The main header should be 11/4" , not 1" for starters.
    The design temperature for Plattsburgh is -20 degrees. That means the system should keep the home at 68 degrees when it's -20 outside. If not, someone didn't do their homework.
  • JStar JStar @ 8:27 PM
    Contact this user


    You are in upstate NY, but where exactly?
    - Joe Starosielec

    Guaranteed performance. Guaranteed energy savings.

    Serving all of NJ, NYC, Southern NY State, and eastern PA.
    Consultation anywhere.
    (Formerly "ecuacool")
  • Nasdaqsam Nasdaqsam @ 8:59 PM
    Contact this user


    I'm at the top northeast corner of ny.
  • Hydro Hydro @ 6:59 PM
    Contact this user


    Did you install this "system", or someone else, and are you the homeowner? Just curious, I have seen this user name before
    "If you don't know where you are going, any road will get you there"
Post a Reply to this Thread