zlacker

>>PaulHo+(OP)
I've been keeping an eye on heat pump water heaters for awhile, but right now they mostly make sense in warm climates. The big problem is they're still specialty products and marked up like crazy, but also they tend to use cheap components which makes them loud and prone to failure. If you run A/C for the majority of the year then they pay themselves back reasonably quick, barring early failure, but in colder climates they make your house work that much harder to keep the space warm.

The most optimistic hope is that the government mandate will force enough demand that manufacturers can enjoy some economies of scale and actually try to compete on price. I don't think this will happen anytime soon.

>>jandre+Cr3
I think a heat pump only for water isn't the right way to go. In the EU, new systems I see use a single heat pump for all heating and cooling in the house including heating water.

I do miss my natural gas on-demand water heater from when I lived in the states though. Unlimited hot water was nice, and it took up almost zero space.

>>matwoo+Qt3
> I do miss my natural gas on-demand water heater from when I lived in the states though.

Isn't that what we call a combi boiler in the UK (and Europe?) I've recently moved from having a big hot water cylinder to a combi. The space saving is nice, but there are downsides.

Waiting for the hot water to come through is annoying and I'm often just wasting cold water waiting for it to come through hot. There is a "pre-heat" feature which would be nice, but then it would keep it warm 24 hours a day which is ridiculous. Maybe some better boilers can time the pre-heat. That would probably be close to perfect.

The other downside is it can only really supply one tap with hot water. So if someone is having a shower and someone else runs a hot tap it can be unpleasant. Requires some coordination between householders.

All in all I would definitely prefer a cylinder if I could afford the space it takes. Modern cylinders are incredibly efficient. I once turned the heating off for a week while away on holiday and when I came back the water from the cylinder was still tepid.

>>globul+ah5
The natural gas powered Rinnai I had could supply 2 showers and a sink with hot water at the same time just fine. It did take a little longer for hot water to come out the tap beyond the usual flushing the cold water out, though it was not a significant amount of time.