Drain Water Heat Recovery (DWHR) options for shower drain in crawlspace?
I am about to start a bathroom remodel and am interested in adding drain water heat recovery (DWHR) to the project. The main motivation for this is not “payback”, but rather to improve the performance of my heat pump water heater.
My home is on a crawlspace with good access to plumbing. However, being a crawlspace, there is more limited vertical height compared with a full basement. There *may* be just enough vertical height for one of the shorter DWHR units, but this depends on where the drain outlet on the DWHR needs to be connected.
I have two questions:
1. What are my options for the DWHR unit’s drain outlet connection? Does this need to connect to the main plumbing stack, or can it be connected downstream of the plumbing stack, e.g., directly to the home’s drain line?
2. I like EcoDrain’s design and efficiency, and their shortest units are 36″ (3″ pipe) and 32″ (4″ pipe). I am not a plumber, but I assume I can use either one of these options (3″ or 4″ diameter) with an adapter for a typical 2″ shower drain – is that correct? Are there any considerations on choosing the 3″ vs 4″ diameter models that I’m not aware of?
Thanks for any advice – I’d really like to install one of these units during the remodel!
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