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Radiant New install

Dave Z.
Dave Z. Member Posts: 1
I am building a home of my own and am very interested in installing radiant heat. This is a 2000 sq. ft. main floor with same in full basement. I will probably have 2 zones per floor plus 1 for my 2.5 car garage. I will also have a 1200 sq. ft. shop, approx. 100 feet from my house with 1 zone and a separate 300 sq. ft. greenhouse 1 zone. This totals 7 zones plus one for my water heater.

I would love to hear what input anyone has to say. I have never done a radiant install before. It is becoming more and more popular here in Utah.

My immediate questions are regarding warm board flooring for the main floor and what is the best application to install PEX in/under concrete? Also based on the sq. ft. above, how much 1/2" PEX should I need to order?
Secondly I'm curious if I go with a tankless wall mounted unit is 90% efficient worth the extra cost over an 80%? I was told the Prestige, condensing high efficientcy stainless steel gas boiler would work very well for my application. This unit boasts 96% efficient at low temp.

I would love to hear back from any radiant gurus.


  • Contractor
    Contractor Member Posts: 41

    Warm board adds quite a bit of height to a floor and has a hard aluminum layer on the top of it which i dont particulary like when hardwood is going to be fastened directly on top. Ive installed the climate panels made by viega a few times and the homeowners love the look of it when im done. they mention they want to put some plexyglass on top of it and have that be their finsihed floor lol. not to mention it has a fast response time just like the warmboard does. the climate panels only add a 1/2" rather than 1-1/8" to the toal height and they have the aluminum on the bottom rather than the top so fasening hardwood is made easier (your floor guy will like alot more). now if you are using a floating floor both applications will work fine.

    As for the in concrete application insualting the sides and around the edge (about 4-8 feet in) then zip tieing or clipping to wire mesh will work just fine. Also using clips that screw into foamboard.
  • Jim_65
    Jim_65 Member Posts: 184
    New Construction?

    I may be confused but if this is new construction then why would Warmboard's thickness be an issue? It not only provides you with a quick responsive radiant panel but it also is a structural sub-floor.

    Why would you pay to install another panel system directly on top of a sub-floor if you could have it all in the Warmboard. Climate panels plus sub-floor thickness would raise the level to 1-1/4".

    If I am mistaken about if this is retrofit or a new construction project then a on top of the floor panel system may make more sense.

    As far as hardwood applications go the installers can see the tubing just as easy with the Warmboard and I have never heard of a aluminum issue.

    As the homeowner I would start this process out by finding a qualified contractor to do a heat loss calculation followed by a quality design. Depending on your location in Utah and if you can locate a company to provide you services I would look on this site for assistance or NRT.Rob.

  • Josh_10
    Josh_10 Member Posts: 787

    Ditto Jim, because Warmboard is also the sub-floor I find that it has the lowest profile of ANY track system. It also has the best performance you can get. I love this stuff. I had to try alot of different products before settling on Warmboard.

  • Ditto Josh; and the cost differential, once you save the subfloor, is not that large. Quik Trak is very expensive stuff for a slower install and inferior performance. Personally, I like to call it Quik Trash, though it does have its uses.. i.e. when you absolutely, positively can only have a 1/2" height buildup, and it has to go on top of the subfloor. Other than that one circumstance, I can't see a single application where it makes any sense at all; Raupanel is far better for a retrofit, Warmboard for new construction.

    Heck, heavy plates in the joist will do a better job than Quik Trak, for about $2 a square foot less and better balancing opportunity since you aren't stuck with a 20 degree design dT.

  • Hi Dave.

    First, in Warmboard, use PEX-AL-PEX, not PEX. They have an approved tubing list; use it.

    Second, don't install a foot of pipe or have a foot of pipe installed until someone has done a room by room heat load calc and figured out how all of this is going to tie together.

    Third, a wall hung BOILER is an excellent choice. A Wall hung Tankless Water Heater is rarely a good choice. These are two very different animals so do not confuse the terminology. The prestige is a wall hung, modulating/condensing boiler that could serve you very well and would most likely be the kind of boiler you want to us here, especially if the whole system is going to be low temp.

    My general take is "80%" boilers never get there, unless you invest heavily in electronic firing controls. the "92%" mod-cons usually exceed their ratings on low temperature systems, IF they are properly installed and the system properly designed.

    That takes know-how.

    The number one criteria in heat source selection is always this: what can your local installers provide, install, and SERVICE with CONFIDENCE? That is far, far more important than brand loyalty.
  • Josh_10
    Josh_10 Member Posts: 787

    Not to mention the severe pressure drop due to the 5/16" tubing!
This discussion has been closed.