Ducted Heat-Pump Water Heater
Hello. I recently purchased a small home near Tillamook, OR that badly needs a new water heater. I’m very interested in a HPWH to recue energy usage, however I believe the only configuration that would make sense is to duct the intake and exhaust to the outside.
The reason: the installation location will be a tiny utility closet, so it will have to be vented to somewhere. The house is heated by a terribly inefficient open-circuit electric furnace–yes, my furnace pulls intake air from my unconditioned crawlspace, heats it on electric coils, and then the house is passively vented to the outside (not to the crawl). I didn’t know such a wretched design exists, but I have it. That furnace will certainly be replaced as soon as I can, but for now that’s what I’m dealing with. So, if I were to pull the HPWH heat from inside the conditioned space, that’s where the replacement heat would come from. And due to my location, I never need air cooling, so discharging inside also is a penalty. Thus my conclusion that I’d need to duct outside.
Questions: does it make sense to use a HPWH in this scenario? The air temperature is cool but rarely cold; hardly ever approaches freezing. I’ve read the articles and discussions here (e.g. Saving Sustainably: Installing a Heat-Pump Water Heater – GreenBuildingAdvisor) and I’m not sure. Dana seems skeptical, but it looks like I’ll still achieve something like a COP of 2 (versus close to 4) based on a study he linked to. If I did go this route, would pulling the intake from the unconditioned crawl make sense? I’m thinking it’d be warmer than ambient air due to ground heat.
Thanks for your time,
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