Hot water recirculation loop with PEX homerun system?
Has anyone played with the idea of doing a hot water recirculation loop with a pex manifold homerun system?
My desire for a recirc loop is mostly inspired by Gary Klein and my reading/watching of his work. Although he doesn’t recommend a home run system because you can’t recirculate hot water…. well, I think it might be possible. Maybe I’ll sound crazy here, but what can I say, I love systems design.
I see this as 2 issues:
1. Is it doable?
I imagine the easiest way would be a circulation pump on the output side of the hot water tank and before the viega pex manifold. each selected hot run (showers and faucets) would have a Tee below the fixture and a checked return pex line. then a return manifold on the supply side of the hot water tank completes the loop. (I can draw a diagram if needed)
I don’t see why it wouldn’t work, but I’ve never seen a system like this in action. The idea being this system would allow one pump to handle all the circulation vs an individual pump at each desired fixture.
2. Is it more efficient?
The idea of turning on a shower or faucet and dumping a bunch of water down the drain as we wait for the hot water line to purge (behavioural waste) gets me a little upset. Its inefficient with resources and user experience. Trunk and branch systems are even worse for wait times because the larger diameter water lines and low flow shower head output create a slow hot/cold mixing within the pipe. That being said, I’ve never played with a homerun system before but I’ve heard how a 1/2″ pex line purges water quite quickly due to its low internal volume.
I personally wouldn’t be able to do an accurate model, but my question is along the lines of: Would the small amount of water dumped from a 30′ 1/2″ pex line outweight the energy used of recirc pump + hot water tank running for 10mins once a day. Which would actually be more green?
Any energy and mechanical nerds out there? I would love to hear your comments.
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