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Another DIY repair, non-barrier tubing

GroundUp Member Posts: 1,926
Hi all, I was wondering if anyone has an install photo to share where non-barrier tubing was used and a heat exchanger was necessary to split the system. I've done it a thousand times with atmospheric OWB systems, but never with a wall hung unit and am trying to picture a better layout than my little brain can come up with.

Customer installed 2 loops of Dura-Pex in his garage slab and another 2 in his kitchen, 60 feet away. 50 gallon electric WH in the garage with an 007 literally dangling from 1/2" Dura-Pex off the relief valve port with both domestic ports on top capped. No expansion tank, air eliminator, or any means of control besides one of those inline 120v stats you'd use on a Torpedo heater in the garage to run the circ, so the kitchen only gets heat when the garage gets heat. Oh, and both 300ft loops in the kitchen are fed across the basement with 60ft of 1/2" from the garage. I was called out to discuss adding the new 1300 sq ft detached shed to the system and integrate all 3 spaces to a single new boiler (detached via foam filled underground from the basement, 120ft) and possibly add 800 sq ft of underfloor under the living room. We've since settled on a separate unit for the detached to avoid the underground piping, but the non-barrier tubing in the house and garage still pose an issue and we've settled on an Electro boiler which is mild steel. My drawing and calculations say to separate the boiler from the emitters with a 30 plate HX and basically pipe it P/S with the HX being in place of the hydro sep, with separate expansion tanks and reliefs on each side of the plate. What say you?


  • Alan (California Radiant) Forbes
    Seems as though you could find a heat source and components that can tolerate oxygen and non-barrier tubing. It could save you and the homeowner a lot of money if you don't need a HX.

    I'd try here first:

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • GroundUp
    GroundUp Member Posts: 1,926
    Thanks Alan, but no. The HX cost less than a pump, I'm not worried about that. We've settled on the Electro because they're the best in the business and manufactured in a neighboring town, plus I have a slightly used unit on the shelf that will fit his heat load perfectly at a 75% discount from new. That part is non-negotiable at this point. More or less just looking for a visual on a setup like this or a confirmation of what I've proposed being accurate.