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Re:Hitachi launches CO2 heat pump water heaters with solar-f... by UncleOxidant on Thursday September 10, 2026 @12:51PM (#49646766)
As an American reading this I feel like we have fallen far behind when it comes to home HVAC (and bath) tech.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by autoexec on Thursday September 10, 2026 @01:26PM (#49647356)
Anyone who has used a nice Japanese toilet knows the US is behind in terms of bathroom tech, but personally I'm glad that nothing my bathroom is controlled by app and that I don't have to spend my time worrying about what time of day it is when I want hot water or air conditioning. I hope my power company never decides to start with "surge pricing" so they can hike up my rates any time it's too hot or cold outside.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by maigret on Thursday September 10, 2026 @01:37PM (#49647503)
Solar + batteries is cheaper than ever. Americans are often full preppers and DIY but when we speak about energy autonomy and efficiency they immediately get some weird allergy.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by rconti on Thursday September 10, 2026 @08:43PM (#49652109)
Some of us still believe in market incentives.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by foobarian on Thursday September 10, 2026 @09:04PM (#49652263)
People keep saying this and yet I struggle to find a decent sized house battery that doesn't cost as much as a new car.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by maigret on Friday September 11, 2026 @06:01AM (#49655906)
What kind of electricity usage do you have? Because a used electric car probably around 20k provides you with easily 50+kwh in car to grid, + you get a working car for free.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by kvuj on Thursday September 10, 2026 @11:36PM (#49653256)
Electricity here in Quebec is dirt cheap, state owned and 100% renewable. Our first 40 kWh per day is 7 cents per kWh which is roughly 0.05 USD.

Any calculations I've done made it unfortunately useless to buy solar and instead favoured investing the money in the stock market.

Re:Hitachi launches CO2 heat pump water heaters with solar-f... by maigret on Friday September 11, 2026 @08:19AM (#49657184)
Absolutely in that case it would be more for fiddling and having a conversation starter with friends. It also depends on how reliable your grid is etc.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by quickthrowman on Thursday September 10, 2026 @02:02PM (#49647881)
Japan has no domestic source of oil or natural gas. The US has so much natural gas that it’s flared off to the atmosphere in some places. Natural gas is insanely cheap to heat with as a result and condensing boilers are extremely efficient. This created a scenario where heat pumps may be more efficient, but they might still cost more to operate. The raw cost of gas excluding pipeline and connection costs in my state is $0.57 for what is equivalent to 29.3kW of electricity. It’s very hard to beat that if you have a 98% efficient boiler, even with a COP of 4 if you’re paying $0.15/kWh, that means the equivalent amount of heat moved would cost 0.15*7=$1.05 or just under twice as expensive.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by Groxx on Thursday September 10, 2026 @02:35PM (#49648359)
Yep - where I am, it's moderately more expensive to use our heat pump to heat the house (at basically any time of year) than to use the gas furnace, and approximately nobody has a heat pump water heater. And with datacenters trying to move in, that equation may get even worse in the future. Gas is surprisingly, weirdly cheap, often not even metered in apartments.

Having two options during cold winters can pay for itself with one emergency repair though, or be a massive savings if it can't be fixed fast enough and pipes burst.

Re:Hitachi launches CO2 heat pump water heaters with solar-f... by quickthrowman on Thursday September 10, 2026 @05:44PM (#49650548)
The backup heat source of a heat pump is extremely nice to have if your furnace craps out, just shut off the gas supply and let the heat pump do its job. If I had to replace my A/C condenser I’d probably opt for a heat pump to replace it so that I’d have that option too.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by throwaway2037 on Thursday September 10, 2026 @07:41PM (#49651630)

    > Gas is surprisingly, weirdly cheap, often not even metered in apartments.
Yikes. How is this possible? My guess: You are paying for it in a building fee.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by Groxx on Thursday September 10, 2026 @08:05PM (#49651799)
Generally yes. But also it is sometimes like half the cost or less for comparative heating power, and for air-heating an apartment in the middle simply doesn't need anywhere near as much, and you literally heat each other so actually-fair costs are fuzzier. Gas bills in places that didn't include it would often be like $15/month in the middle of winter, hardly worth the administrative and hardware costs.

One of the houses I rented many years ago didn't even have metered gas. We paid a "hookup" fee to the city (like... $40/quarter?), and they didn't care how much we used, as long as it wasn't for commercial purposes. I assume the city had something for detecting extreme use or leaks, but that's probably it. It was a somewhat strange property though.

Re:Hitachi launches CO2 heat pump water heaters with solar-f... by dns_snek on Friday September 11, 2026 @02:05AM (#49654108)
> and you literally heat each other so actually-fair costs are fuzzier

What you're describing is closest to "actually fair" I think we can get. A neighbour of someone I know leaves their apartment empty for long periods of time and when they're gone they just shut off their heating completely and leave all of their neighbours to pick up the bill - each apartment has their own heating system but they share walls, floors, and ceilings.

Re:Hitachi launches CO2 heat pump water heaters with solar-f... by Scoundreller on Friday September 11, 2026 @12:40AM (#49653634)
> The raw cost of gas excluding pipeline and connection costs

In Ontario Canada; your gas hookup is CAD$29/month (~US$21) every month of the year, on top of a per m3 charge for delivery to you before the gas cost itself. So on a smaller or well insulated residence, capping that pipe really helps push the economics in favour of heat pumps.

https://www.enbridgegas.com/-/media/Extranet-Pages/ontario/r...

Re:Hitachi launches CO2 heat pump water heaters with solar-f... by rsynnott on Friday September 11, 2026 @06:46AM (#49656213)
> It’s very hard to beat that if you have a 98% efficient boiler

You do not, to be clear, have a 98% efficient gas boiler. You _may_ have a gas condenser boiler which claims 98% efficiency in absolutely ideal circumstances, but realistically you're likely not getting close to that. AIUI 80% efficiency is fairly normal for real-world condenser boiler usage (non-condensers were more like 70%)

Re:Hitachi launches CO2 heat pump water heaters with solar-f... by pezezin on Thursday September 10, 2026 @07:57PM (#49651744)
Don't feel bad. I also live in Japan, and in my experience most homes (mine included) still use gas boilers and kerosene heaters. Not to mention that houses are built to be as cheap as possible, so insulation is almost non-existent and you boil in summer and freeze in winter.
Re:Hitachi launches CO2 heat pump water heaters with solar-f... by KPGv2 on Friday September 11, 2026 @12:51AM (#49653696)
Yeah, mini split ACs are so superior to American-style central air. I installed them into a couple rooms and removed the central air ductwork from the attic there. Thinking about doing it with the other rooms. Less power usage, every room gets its own temperature setting, quieter.