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Radiant Design Temps

Cheeze-Tech Member Posts: 84
As far as the basement goes, I'm not 100% sure 'cause I wasn't there when it was installed. I believe they had 2" styro with 16 centers. The upstairs has 5 zones with each having 2-3 loops/around 270' per loop. The staple up is in the joist which are 16" wide. Again we used rehau's 4' long solid alum plates that you snap the tubing into from the basement side. Why just floor warming, good question. One of two owners of our company has been running this job. He is a forced air guy and was only giving the homeowner what they asked for. If it had been me I would have done the whole house in radiant as main heat source. As it is 3/4 of the first floor is floor warming. Dumb!


  • Cheeze-Tech
    Cheeze-Tech Member Posts: 84
    Design Temps for radiant system

    I am working on installing a radiant system in a new house (I am a contractor) and looking for suggestions for supply water temps. We have a new designer at our distributor and I'm not sure about him. The first floor has staple up in the joists using rahau c fin solid alum plates. We are just doing floor warming. We have 5 zones with flooring being carpet, tile, and wood. My plan is to use a tekmar 509 stat with floor sensor tucked in a groove on the top of the subfloor. My questions are these: What supply temps should I use for each of the above mentioned floor coverings; and how should I set the tekmars up as far as temps. I was planning to use them in floor sensing only mode. We are using the W/M Ultra 3 which allows for 3 separate water temps. We have in floor in the basement slab which we will run at 120 F. The designer wanted to set the rest up for 160 F and use a mixing valve for the basement, which defeats the advantage of the 3 temp capability. Your thoughts would be appreciated! Also what gpms would you run thru the loops (1/2" pex, around 270' each)?
  • Mark Custis
    Mark Custis Member Posts: 539

    has a table of r-values for various types if flooing. 120* sounds high for the basement what is your O/C spacing and how much insulation?

    5 zones or 5 loops? What kind of manifold? What chooses the boiler temperature? What is the O/C on the staple-up? Why just floor warming?
  • Mark Custis
    Mark Custis Member Posts: 539
    Life just got tougher

    I use mixing valves to set floor temps, as it takes some of the rocket science out of the systems. Most of the time I use dumb mixers unless the customer has to have the latest and greatest.

    The basement if on 16s will stripe but it will work.

    Lets worry about the controls not the tempurature.

    The controls will depend on piping. May I assume one manifold per zone? What controls each zone? Zone valves or pumps? If the rest of the comfort comes from room thermostats controlling F/A then your idea about floor sensors should work. I tend to work with room stats to control radiant, so bringing on the floors with a call for heat would be what I might do.

    Zone valves for the zones and an ECM pump would work if propperly piped.

    What tells the boiler what tempurature to use?
  • Cheeze-Tech
    Cheeze-Tech Member Posts: 84

    Sorry I forgot to mention that the boiler can take up to 3 different "thermostat" inputs and you assign each one its own tempurature and priority status. So depending on which "tstat" calls for heat will determine which of the three temperatures the boiler will run at and what priority level it gets.
    The basement centers are probably closer than that, I just don't know the number.
    To answer your other questions:
    Each zone will be on its own manifold, and I use pumps for each zone. I was going to use just floor sensors to control the floor warming because they have forced air for primary heat upstairs and I'm hoping to keep the two from clashing to much. This is not how I would have designed the house, but I'm trying to reverse engineer it after the damage has been done. Fun! Fun! So I'm mainly looking at recomendations for supply temps. Since the boiler gives me 3 to work with I though I might as well take advantage of it.
  • Mark Custis
    Mark Custis Member Posts: 539
    All this communication

    with out pictures.

    Back to temps.

    Pumps for each zone make that easier.

    I have done radiant floors since Dan H., invented steam. He told me about radiant heating in Rome. Your plan is to use the boilers ability to produce temperatures by call for heat. That will work if the priorities are correct. The piping is another issue.

    I have found that no matter how hard I think and how hard I listen to the customer, I am wrong. The floors are not____ enough.

    I would pipe the system so that similar floor zones are grouped. All hardwood together, all carpet together and all tile/ceramic together. I would learn the boiler controls so that if Mrs Homeowners needs warmer feet in the tiled area you can do that change.

    I guess the point is there are two sets of plans for every system; as planned and as built. You will be the hero if you can make what as built turn into as planned or into what the customer really wants.

    Do not worry about floor temps until the final commissioning and then the final, Mrs. Homeowner. Use the Radiant Pannel Association's r-value guide to help you group zones. Set a target not a rule. You must have more r-value under the floors than above.

    I spec and use Rehau.
  • Cheeze-Tech
    Cheeze-Tech Member Posts: 84

    Basicly I was looking for starting places as far as supply temps, gpms, and tekmar settings. My experience too has been that you have to do some tweeking to radiant systems once the homeowner is in. A bit different then the forced air world of throw it in and walk away. Thanks for your input. I copied the r-value info off and will address that with the homeowner in regard to their flooring choices.
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