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Heated floor layman's questions

PieCa Member Posts: 31

I'm not a specialist. I'm just a curious customer, asking about some of the aspects of radiant floor heating that I don't look to lost when the contractor will be onsite :) So, I'd love to have your explanations and/or opinion on the following points.

1. A very stupid one to start with :) with a boiler servicing both steel radiators and the heated floor, I understand we need to do some zoning. Is that true even if the heated floors will be only on one room? Like it would be one zone only. Or is the zoning referring to the fact we need different temps for the floors and the rads?
2. Also, what actually is zoning? Is that separating a part of the closed loop with a mixing valve to adjust the temperature? Or it has nothing to do with that? If not, how do we achieve different temps?
3. Where is the best spot for a manifold, assuming that the lenght of the loops are not an issue. The closest from the boiler? My basement is not insulated. The walls can get cold, is that something to consider when placing the manifold, and/or the return?
4. Is a heat loss calculation a MUST in a heated floor project? Can we ask the output of this from the contractor? Or does ot look like defiance...

Thank you :D


  • Jolly Bodger
    Jolly Bodger Member Posts: 209
    1. It is very likely, and best practice, to have different water temps for rads and infloor. Though depending on the load calc, rad area, floor area, floor install method, floor covering type, loop spacing, the water temp needs could be the same. This does not necessarily mean you would have multiple thermostats. But why wouldn't you?
    2. In your case you would have a low temp loop and a high temp loop. Those are not really "Zones". Zone is generally used for an area that has it's own temperature control. Each thermostat controls a "zone".
    3. Best location is accessible and close to the floor. Typical install with 1/2" PEX will be flowing at 1/2 GPM. You don't want that slow moving water to pass through a lot of unconditioned space. The loops are also higher resistance to flow so they should be kept short.
    4. Heat loss calc is always a must. Unless you don't care if it works correctly. Every situation is different. In the case of infloor you will also be calculating and designing to the install method and finished flooring type. If the contractor does not want to show it to you he did not do one. He should also talk to you about the options and how you want to use it.
  • newinnj
    newinnj Member Posts: 36
    Small disclaimer. All information that is stated is from all of the wiser ones who guided me. 1. I have a mixed situation at home. Two zones are wood floor radiant and one zone is poured concrete floor. My boiler has emiter type heat selection. You will have to pick the lowest floor temp. I had to use a high mass (aka concrete) that runs at a lower temp. Using another floor setting will increase the water temp and potentiallly crack the concrete floor 3. I made a mistake and should have done this first. Insulating is critical and important. Since my tiny sub basement is now properly insulated the heat from the boiler room alone heats up the space. I don't need to run that zone. 4. You might want to find a radiant designer on this website. That is a diiferent description than a contractor.
  • hot_rod
    hot_rod Member Posts: 16,278
    With careful design and a low load structure it is possible to run both floor radiant and panels on one temperature.

    A friend in upstate NY just fired up his design with an A2WHP supplying 95°F to a system with both emitters on one temperature.
    On a recent 0° evening the home was comfortable with 95° SWT.
    That puts the HP in a nice operating efficiency range.

    About 8 KW of solar PV offsets some of the electrical cost on that 4 ton system.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream