4 ms·

Or my alternate hot-take (or cold-take?): Great, now if someone can crack the engineering challenge of an air-to-water heat pump water heater that doesn't turn

Or my alternate hot-take (or cold-take?): Great, now if someone can crack the engineering challenge of an air-to-water heat pump water heater that doesn't turn your basement into a walk-in refrigerator, that'd be great.

metadat 4y ago
Add a server rack and things will warm up down there.
- kennywinker 4y ago
  Make it a liquid-cooled server rack and we can cut out the hot water heater entirely
  - thrill 4y ago
    Run it on solar power and pull the water out of the atmosphere and we can save a bundle on running power and water.
ulrikrasmussen 4y ago
Why would it do that? The heat exchanger is placed outside.
- thaeli 4y ago
  Heat pump water heaters mostly draw from room air.
- jacobolus 4y ago
  Common heat pump water heaters (often called “hybrid”) have a heat exchanger on the top of the tank, and pull heat out of the surrounding air.
chrislund 4y ago
Depending on your market, Sanden and Mitsubishi make air-source DHW heat pumps where the evaporator/heat source source is remote (i.e., outdoor) rather than integrated with the tank. I can't speak to Mitsubishi's line but IIRC Sanden has the DHW go straight to the outdoor unit, but then you may need freeze protection, which I think Sanden provides via heat trace. When my current water heater bites the dust, I plan on getting a Sanden, and looking in to the feasibility of making a glycol loop between the outdoor unit and an indoor "indirect" tank to eliminate the need for freeze protection.
- kennywinker 4y ago
  Thanks for the tip! Where I am Mitsubishis seem to only be available through big-name installers, and the only thing they offered me when I talked to them was the all-in-one style that cools your basement. Living in an old house with not great insulation between floors, that was a hard no-go. I'm now googling the Sanden ones and getting some promising results I hadn't seen before.
ortusdux 4y ago
Rheem, the brand HD carries, is easily ductable. Both the inlet and outlet can take 100' of 8" ducting. I set mine up with T's, electric dampers and some simple logic.
kevstev 4y ago
How cold does it really get? This could be great for a wine cellar.
Danieru 4y ago
What you want is an "Ecocute". It is a air source heatoump supercritical co2 tanked hot water system. Designed for the Japanese market. Without install a 500l tank version costs about 1.5k usd in Japan. So you should be able to get one installed for about 20k usd in the US. If you beg the HVAC guy of course.
1123581321 4y ago
What challenge? Any of the HPWH brands can duct exhaust out of the home. Try Sanden if you want more than that.
- kennywinker 4y ago
  The all-in-one heat pump hot water heater pulls in warm air from its surroundings, pulls the heat out of it and puts that into its water. Then it lets out its "exhaust" colder air. Ducting to outdoors improves things, because it doesn't put that cold air back into your basement / utility closet, but you're still pulling heat out of the air - which your house heater now has to put back into the air - and unless your space is perfectly airtight, that's probably just going to be sucked in via the nearest air gap to outside. It's a bad system. Split systems make sense, and I know they exist, but they seem weirdly rare. Some data on this topic: https://www.energyvanguard.com/blog/will-a-heat-pump-water-heater-freeze-your-basement/ https://www.energyvanguard.com/blog/will-a-heat-pump-water-h...
  - 1123581321 4y ago
    The ducting brings the temperature drop to an almost unnoticeable delta. If you are worried, just install it near your furnace. It’ll eat radiant heat from that corner that would otherwise go into the walls, egress windows etc. Every other part of the year, you either don’t mind or benefit from the cooling. I have the stats from my own Rheem to know I’m coming out ahead financially during winter and also haven’t seen a meaningful swing in the basement climate. I’m a regular participant in that linked blog, too. :)

metadat 4y ago

Add a server rack and things will warm up down there.

kennywinker 4y ago
Make it a liquid-cooled server rack and we can cut out the hot water heater entirely
- thrill 4y ago
  Run it on solar power and pull the water out of the atmosphere and we can save a bundle on running power and water.

ulrikrasmussen 4y ago

Why would it do that? The heat exchanger is placed outside.

thaeli 4y ago
Heat pump water heaters mostly draw from room air.
jacobolus 4y ago
Common heat pump water heaters (often called “hybrid”) have a heat exchanger on the top of the tank, and pull heat out of the surrounding air.

chrislund 4y ago

Depending on your market, Sanden and Mitsubishi make air-source DHW heat pumps where the evaporator/heat source source is remote (i.e., outdoor) rather than integrated with the tank. I can't speak to Mitsubishi's line but IIRC Sanden has the DHW go straight to the outdoor unit, but then you may need freeze protection, which I think Sanden provides via heat trace. When my current water heater bites the dust, I plan on getting a Sanden, and looking in to the feasibility of making a glycol loop between the outdoor unit and an indoor "indirect" tank to eliminate the need for freeze protection.

kennywinker 4y ago
Thanks for the tip! Where I am Mitsubishis seem to only be available through big-name installers, and the only thing they offered me when I talked to them was the all-in-one style that cools your basement. Living in an old house with not great insulation between floors, that was a hard no-go. I'm now googling the Sanden ones and getting some promising results I hadn't seen before.

ortusdux 4y ago

Rheem, the brand HD carries, is easily ductable. Both the inlet and outlet can take 100' of 8" ducting. I set mine up with T's, electric dampers and some simple logic.

kevstev 4y ago

How cold does it really get? This could be great for a wine cellar.

Danieru 4y ago

What you want is an "Ecocute". It is a air source heatoump supercritical co2 tanked hot water system. Designed for the Japanese market. Without install a 500l tank version costs about 1.5k usd in Japan. So you should be able to get one installed for about 20k usd in the US. If you beg the HVAC guy of course.

1123581321 4y ago

What challenge? Any of the HPWH brands can duct exhaust out of the home. Try Sanden if you want more than that.

kennywinker 4y ago
The all-in-one heat pump hot water heater pulls in warm air from its surroundings, pulls the heat out of it and puts that into its water. Then it lets out its "exhaust" colder air. Ducting to outdoors improves things, because it doesn't put that cold air back into your basement / utility closet, but you're still pulling heat out of the air - which your house heater now has to put back into the air - and unless your space is perfectly airtight, that's probably just going to be sucked in via the nearest air gap to outside. It's a bad system. Split systems make sense, and I know they exist, but they seem weirdly rare. Some data on this topic: https://www.energyvanguard.com/blog/will-a-heat-pump-water-heater-freeze-your-basement/ https://www.energyvanguard.com/blog/will-a-heat-pump-water-h...
- 1123581321 4y ago
  The ducting brings the temperature drop to an almost unnoticeable delta. If you are worried, just install it near your furnace. It’ll eat radiant heat from that corner that would otherwise go into the walls, egress windows etc. Every other part of the year, you either don’t mind or benefit from the cooling. I have the stats from my own Rheem to know I’m coming out ahead financially during winter and also haven’t seen a meaningful swing in the basement climate. I’m a regular participant in that linked blog, too. :)