Heat pump water heater in conditioned crawl
blackfeet
| Posted in Energy Efficiency and Durability on
Hi all.
Building 2,000 sf in Washington zone 4 Marine.
Will have a tall crawl space (on one end). Wanted to put the HPWH down there. But I also want set it up as an unvented crawl space. My understanding is that HPWH blows cold air. Also, Washington State Energy code recommends that a HPWH be in an unconditioned space.
I could put it in the garage which will be unheated, but insulated. The garage will have a small apartment over it. So again, is putting more cold air into the garage not a good idea (floor above will be insulated to R38 mineral wool).
Thanks in advanc.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
If the Washington energy code says that, well, they're dumb. They work best in conditioned space. Crawl spaces are good because people tend not to be right up against them.
Maybe I missed it buy all the HPWH I have seen are too tall for a crawlspace.
I agree most HPWHs need to be over 50° and are disabled much below that.
Walta
Thanks for your replies DC and Walta. The crawl space is tall in one area because we are on a slope. Its about 7 feet tall.
The only potential issue with a “tall crawlspace” install is getting the equipment there. I replaced an integrated model with a split system to avoid this problem.
https://www.alpha.facebook.com/share/p/18curKVVnB/?mibextid=wwXIfr
Yes, that is a good place for it. Reread the code - makes no sense to put a HPWH in an UNconditioned space. The HPWH will draw heat out of the space, thereby making it cooler.
And as a fellow owner of a sealed conditioned crawl, strongly consider installing a rat slab on the entire thing...
Agree installation inside conditioned space is ideal, but I would recommend venting the HPWH outside the conditioned space. From my experience it acts as a big A/C unit, and in the winter in particular it will drastically cool the crawlspace, since you are in Washington I imagine that you are heating more throughout the year than cooling, and therefore will want to keep your crawlspace as warm as possible.
If you're venting outside the air you're exhausting is going to be replaced with outdoor air that leaks in. If the outdoor air is colder than the exhaust air you're making the problem worse.
There is a very specific, narrow window when venting outdoors is beneficial: when the outdoor temperature is higher than the exhaust temperature, and air conditioning isn't needed. Those are the same conditions when it makes sense to have the heat pump outside, or a split system.
Be sure to consider the condensate removal regardless of where you end up placing it. I'd personally just put it wherever is easiest to access it and where it it would be closest to your hot water loads whether that is the garage or crawl space. You don't want to be dumping your condensate in your crawl space. You may have to get a pump to pump it out. I guess you could go through the wall too or maybe get it to a sewer line. Personally if i couldn't gravity drain the condensate I'd probably default to the garage installation location.
Thanks everyone! I got good information from you all.