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Radiant Floor Help- I'm overloaded w/opinions!

Hi- looking for some factual insight/boots on the ground experience regarding radiant floor heat in my pole barn.

Current state of project: New construction 30x56 shed. Insulated 5" Slab(2" under and on sides). Pex routed before pouring using staples to the foam. Walls are 14' insulated R19 min- north and west wall are more due to prevailing wind and a vendor change(long story). Pex is all run to one manifold- which is fine- it is one big room. Would like this to be heated with propane. I would like to keep the shed at 45-50 degrees- but also am planning for the future when maybe I'd spend more time in there :) Located in Madison Wisconsin area.

Questions I have that I haven't seem so gotten clear answers on:

1)What type of unit to heat(again want to use propane)- have been told tankless, wall mount boiler, regular water heater...

2)Pre-fab boiler panels- good idea? total junk? Experience either way? I feel like I have a simple plan and this could be an

3)Past the type of heater- can you help with like a top 5 of whose to use(I need a name!)?

4) I'm getting lost in the weeds when someone pitches me on circulation pumps and size of boiler. I tried googling my way through both- I'm not familiar enough with HVAC to understand/please give me your experience!

Appreciate your help/experience/opinions!


  • PC7060
    PC7060 Member Posts: 738
    So forgive me if I missed this in your post, have you already poured the slab or just run the pex?
  • JordanP
    JordanP Member Posts: 1
    PC7060 said:

    So forgive me if I missed this in your post, have you already poured the slab or just run the pex?

    Slab is poured. Wall insulation is being finished. Trying to get estimate on heating- hence the questions in the post
  • GroundUp
    GroundUp Member Posts: 1,419
    Long story short, you want a boiler. Water heaters, tank or tankless, are not designed for this type of use and will never perform as well as a boiler nor will they last as long. You're going to want something of the modulating/condensing variety to maximize efficiency, which does require a condensate drain (as would a HE tankless) so I hope you made provisions for condensate disposal before pouring the slab. Pre-fab panels can be great if they're properly engineered, but the kind you find at Menards are not- they're nowhere near ideal in the majority of cases and also use water heaters. Systems like RHT and HPS provide are well engineered and built, but come at a pretty hefty cost too. I have built a number of these types of DIY panels for exactly what you're doing here, custom to your needs, at reasonable prices if it was something you wanted to discuss. Otherwise you'd probably be best off finding someone local who actually understands hydronics, not the plumber down the road who suggests a water heater.
  • HomerJSmith
    HomerJSmith Member Posts: 1,620
    edited February 2021
    What is the size of Pex that you used, what is the length of the loops, how many loop on the manifold? How deeply buried in the concrete is the Pex? Does the Pex have an O2 barrier? Is it Pex A?

    As it is a barn, do you have to worry about manure and urine fumes affecting the boiler or piping?
  • Ahead
    Ahead Member Posts: 2
    5" slab and the tubing lies at the bottom?
  • HomerJSmith
    HomerJSmith Member Posts: 1,620
    edited March 2021
    5" you say, I see, a slow slow sys. I believe I asked some other question.