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new to everything and need help

I have acquired a 40'x80' pole barn garage that the builder/previous owner planned to use in floor radiant heat (concrete floor). The floor was poured in 4 sections and has 3/4" pex installed and sticking up through the floor in each section to be connected too. there is also a harmon pb105 ( I believe) wood pellet boiler . From this point everything else is a clean slate. My goal isn't to keep the garage up to a 60-70* temperature but merely keep the temp high enough to keep things inside from freezing (camper,boat, etc). Although if it would be possible to keep it warmer that would be a huge plus.

I want this to be a closed loop system because the well water i have available isn't suitable without having to filter it . so from this point can anyone help me with what circulator pump/s i should use and possibly a simple schematic of how it should be hooked up to the boiler. Should these be hooked up in a series/ parallel or individual systems ? I see other systems with mixing valves also , like i said before i'm kinda lost from where i'm at . I'm guessing that there is information that i havent included that will be needed but i'm more than willing to help with that if at all possible.

thanks for any and all responses


  • Gordy
    Gordy Member Posts: 9,546
    edited December 2016
    To start a heat loss of the pole barn to determine flow rates, and water temps.

    Was the slab insulated?

    Any idea on how many seperate loops,centers of the loops, and their lengths? Need this to help determine pump sizing.

    Just a start

    JUGHNE Member Posts: 11,021
    In any event the heat loss is a good first.
    FWIW, I would pressure test each loop before investing a lot more into the in floor system. There have been some bad installs that have issues. This would also verify which tube end goes to which loop. IMO
  • Gordy
    Gordy Member Posts: 9,546
    You will need a mixing valve also.
  • SWEI
    SWEI Member Posts: 7,356
    And perhaps a buffer tank.
  • hogglett
    hogglett Member Posts: 3
    ok i talked to the previous owner and there isn't any insulation under the slab just a plastic vapor barrier. (insert sad face). But if it matters each 20'x40' section of concrete has its own pex and the inlet and outlet coming through the slab. He said that he pressure tested each section before and after concrete and all was good , but i will redo a pressure test to be safe. the loops are on 16" centers and the lengths vary between 570' and 600'. Now as if the lack of insulation under the slab wasn't enough, the only insulation on the walls is a bubble foil . and if i done the heat loss correctly and the garage being 40'x80'x14' ceiling that leaves me with 120,960 BTUH which in my head sounds ENORMOUS.

    I know that i can add insulation to the walls and ceiling to help the heat loss, but I'm guessing by what I've read that the lack of insulation pretty much makes heating the slab not a good idea.(although just wanting to keep things from freezing) I'm now wondering if seeings how the boiler is there I may be able to utilize it to heat some radiators or something of that nature.

    thanks again for all the quick responses.
  • Canucker
    Canucker Member Posts: 722
    @hogglett Do you have access to the perimeter of your slab? You might be able to insulate the exterior of it which would help with the heat loss. It's not ideal and there's some digging involved, but might be better than nothing
    You can have it good, fast or cheap. Pick two
  • hogglett
    hogglett Member Posts: 3
    yes the outside of the garage wold be easy to get too so that wouldn't be too big of a deal to get done
  • Gordy
    Gordy Member Posts: 9,546
    Well it's 3/4" pex at least......

    Yup heat loss calc mandatory, and better insulation on walls, ceiling, and slab perimeter. Do your heat loss with present inputs, and then another with insulation improvements. You will see the drastic difference.
  • Gordy
    Gordy Member Posts: 9,546
    Slab perimeter losses I'll bet are 25k