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Radiators vs stapled tubing under subfloor

Ted_9 Member Posts: 1,718
the heat loss that was done first. The G124x/18 is the smallest of that line. It may or may not do the job, but you should ask for the engineering to prove it.

I think Buderus(or some other brand) panel rads would work well here. Here's a nice trick: If the staple up you have is in the higher temp. range, then you could size the panels(think over sizing) for the old house according to the radiant design water temp. and run the whole house constant circ. with one temp. You'd have to get the Buderus R2107(out door reset control with domestic hot water priority) and BFU room sensor( for indoor temp. feed back). And every panel would get a non electric thermostatic radiator valve. You'd have temp control in every room.

Only thing I don't know is how the Amtrol would work with the R2107, since I don't use Amtrol.


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  • Annie Hall
    Annie Hall Member Posts: 28

    When we did a significant addition to our house, we went with radiant in-floor heat. Love it! But we left the old part of the house with the existing in-wall electric units for heat -- hate them!!! So now we are ready to remodel the old part of the house into a rec room and we are thinking it would be great to tear out those electric units and use our boiler to heat the old part of the house with hot water.

    We have a Buderus boiler (model G124X18) which heats our DHW (with an amtrol hot water heater) and provides the hot water for the radiant system. I asked the installer to size the boiler so that the old part of the house could eventually be included in the system. So lets assume they did.

    The old part of the house consists of 550 sq. ft. of what will be rec room, a small bathroom and a bedroom/office of approx 120 sq. ft. The floor is carpeted, and the pad is supposed to be compatible with radiant heat. The carpet is a low-pile "commercial" grade. The subfloor is wood and over a crawl space.

    As far as I know, we have two options: One option is to pull the insulation from under the subfloor and staple up tubing for radiant heat. I understand there is some sort of reflector that is supposed to minimize heat loss to the crawl space, and then the insulation needs to be reinstalled. Option two, as I understand it, would be radiators -- these I know nothing about.

    Could I please get some feedback on this from you experts? I've got our contractor coming back to give me a design suggestion and bid -- but they are so busy it will be a few weeks before they can come out. In the meantime I'd like to educate myself on these options. Any drawbacks I should know about? Is the cost likely to be greater for one as compared to the other?

    One additional thought: Currently we only heat this space when we are in it. With in-floor, I know you leave the heat on all the time, but this space won't necessarily be used every day. Are radiators good for quickly heating up a space (turning up and down the heat as needed)?

    Thanks for any and all advice,

  • jp_2
    jp_2 Member Posts: 1,935
    quick test

    if you have anymore "real cold" days, see how long the boiler runs in an hour, this will give you an estimate of reserve.

    my suggestion would be for over sized panel radiators with TRV's. trying to match same running temperature as addition/
  • colbydoglvr_3
    colbydoglvr_3 Member Posts: 12

    One very nice method for radiant under wood subflooring is using Wirsbo extruded aluminum joist track plates. these aluminum heat transfer plates will work VERY well as compared to stapled up tubing. both methods require having a good reflecive insulation barrier. I use a bubble style aluminized reflective barrier with an r value of 6.0 with an airspace of about an 11/2-2 inches and stapled to the sides of the joist. then a layer of regular bat fiberglass is installed depending on the need. the aluminized barrier reflects the radiant energy very well. your boiler sounds to be possibly too small. you may run into problems. consider putting in another boiler like your present one with a tekmar two stage boiler control. one boiler will run and the second will kick in if needed.

    OLD,FANCY cast iron radiators are pieces art work if you can find them but you dont get those nice cozy warm floors...
  • Annie Hall
    Annie Hall Member Posts: 28
    Thanks Ted, I do have the engineering

    I have the engineering calcs and they show a total combined load of 35,765 Btu/hr for the part of the house that is heated with radiant. I don't see domestic hot water included in these calculations, however, and the boiler heats our hot water as well. We do have an outdoor temperature reset in the control loop. I haven't timed how often the boiler fires, but my observation is that in a given hour it will be off more than on. I believe there is an option on the controller that will track boiler hours. If I can figure it out, I will clear that data and see how much it fires in a 24-hour period.
  • Annie Hall
    Annie Hall Member Posts: 28

    True, I love those warm floors. Though this space is mostly carpeted so cold floors are less noticeable. I had thought that staple-up radiant was terribly inefficient compared to the in-gypcrete layout we currently have..what you say encourages me to investigate further. I guess it comes down to the amount of time we expect to use the space -- radiators would be better if the space is used only on weekends, for example.

    Do modern radiators clang and bang? My experience with radiators is very limited...and wasn't particularly good.

    Having to install another boiler will be a deal-killer. We'll end up just keeping the awful electric wall units. Hopefully the contractor will show up next week and I can get better info on the size & load of our boiler.
  • Ed Lentz_2
    Ed Lentz_2 Member Posts: 158

    As a home owner who installed his own baseboard radiators, I can say "They do not clang nor bang". Ours are so quiet you can almost hear the air whooshing over the fintube! :) Just get it sized right and they will be nice and comfy. We are considering building a 3 season room and putting in either staple up or inbed in gypcrete under tile. Good luck
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