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Old 07-09-18, 11:43 PM   #2
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Originally Posted by Drake View Post
I'm putting hydronic pex heating in a high mass concrete slab 14' x 30'. It is for an open room floor plan so it could easily be done with just two loops and meet 1/2 pex length recommendations(approx two 200' loops) spaced from 6" apart near exterior to 12" in the interior. But would increasing number of and shortening the length be better for supplying more and quicker heating if needed(worst case demand). It certainly wouldn't over complicate the system to have 3 or 4 loops in the manifold to any great cost. Structure is super insulated to R50 walls and R80 ceilings. and all the details of Hi-R construction built into the design. Once the slab is poured its too late for any should have's, lol.
The closer the PEX runs, the more efficient it will be.

Old School Amreican rule of thumb is 12" spacing; from my research, Northern Europeans favor closer spacings, with 6" not being unusual. European energy is much more expensive than ours is now.

Sounds like you have a handle on PEX run lengths, and headers, etc.

I'd advise closer PEX runs, similar to the Northern European practice.

You are right about quicker temperature increase, but temperature decrease will be no different.

The real benefit to you will be lower fuel cost over the life of your system.

Hope this helps.


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