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

JordanP Member Posts: 1
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!


  • Youngplumber
    Youngplumber Member Posts: 495
    edited February 21
    Heat loss for the building will tell you the size of the boiler. Brand doesn't matter its more the support for your area. What does the installer use? Who can you get parts from easily? DON'T USE A WATER HEATER. ITS NOT FOR SPACE HEATING. 

    Prefab parts are fine if you think you need them for some reason. I'd prefer to build myself, but would you?

    Sizing circulators is based on the system design and load. Which is after the heat loss.

    More people will chime in with their preferences. Your probably going to want a mod con boiler since you want to switch temps. 
  • PC7060
    PC7060 Member Posts: 270
    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: 1,129
    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: 1,196
    edited February 23
    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?
  • Youngplumber
    Youngplumber Member Posts: 495
    If you don't understand hvac enough you should hire someone to do it for you unless you want to spend the time it takes to design a system that performs over time. There are a lot of people who do "research" and heat spaces but they end up making mistakes, some little some alot, and come back here asking how to fix them. Which is fine if that's what you want. But if you want to set it and forget it without doing a very lengthy deep dive you should hire out and let them teach you the maintenence. 
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