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Community and Q&A

Under-floor hot water coils

peteregodin | Posted in Energy Efficiency and Durability on

I have a hot water underfloor (pex tubing) loosely run in between the joists (as if you uncoiled a new hose) & not close to floor with a foam board attached at btm of joists. It is very slow to reach set points & will over ride up to 2-3 degrees. I was considering attaching the metal plates with the tubes touching the floor but labour intensive with 3 ft crawl space & folks say it will be noisy. Friend suggested to remove u clips that hold the coils & use bubble back insulation to push coils close to floor & then add more insulation Roxall R 20 to bottom & then finish off with the foam board. Any suggestions? Need Help please.

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  1. GBA Editor
    Martin Holladay | | #1

    Here is a link to a GBA article that discusses this issue: Lessons Learned the Hard Way. The author, Ed Welch, agrees with you: heat transfer plates are a good idea.

    If you can't stomach the work associated with installing heat transfer plates, you could try raising the temperature of the water -- but be careful, because higher temperatures can damage some types of flooring, be uncomfortable, and raise your energy costs -- and/or increasing the amount of insulation under your joist bays. Forget the bubble wrap -- use rigid foam, and seal the seams.

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