zlacker

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+(OP)
Which models are you looking at? I was still quoted separate pumps for floor heating and a boiler with the pump built in taking the energy from the air two years ago.

Is it something from nefit by any chance?

>>matwoo+(OP)
Afaik heat-pumps in the EU can provide unlimited hot water–what am I missing?

>>spockz+r1
This is promising.

https://www.pv-magazine.com/2026/01/29/samsung-releases-new-...

> The South Korean giant [Samsung] said its new EHS All-in-One provides air heating and cooling, floor heating, and hot water from a single outdoor unit. It can supply hot water up to 65 C in below-zero weather.

> Dubbed EHS All-in-One, the system provides air heating and cooling, floor heating, and hot water from a single outdoor unit. It is initially released for the European market, with a Korean rollout expected within a year. “It delivers stable performance across diverse weather conditions. It can supply hot water up to 65 C even in below-zero weather and is designed to operate heating even in severe cold down to -25 C,” the company said in a statement. “The system also uses the R32 refrigerant, which has a substantially lower impact on global warming compared with the older R410A refrigerant.”

>>thunfi+a2
Geothermal (and airbased) pumps theoretically do not have unlimited heating capacity. For example my pump (Daikin Altherma Geo 3) has a 180 litre water tank so it can ”only” supply 180 litres hot water at 65 degrees Celsius and takes about a minute to heat two additional lites.

So if I want to quickly scald myself in a 400 litre pool at fifty degrees I can’t. But if I had a gas heater that would be possible!

>>matwoo+(OP)
While they are not as efficient or flexible, they are many times more efficient than resistive electric water heaters. I've installed one with in house air intake (due to construction reasons) in my house and it cooled down the basement by a few degrees (and removed air moisture as an added bonus). In summer the thermal capacity of the ground heats up the basement again, in winter it's a bit cooler, but it still works efficiently.

>>Y-bar+r6
Depends on how you measure unlimited. My hot water heater can pretty much indefinitely supply hot water for a single shower head with a modern water saving design. It can heat faster than 1.2 gallons/minute

>>matwoo+(OP)
> 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+kN1
> 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.

Yeah one of my colleagues has a preheat which can be triggered manually and via automation. They also have a preheat loop which cycles hot water through the entire piping as the boiler is on an edge, so it takes ages for hot water to reach the far bathroom.

>>luckys+S7
They are efficiënt but all that efficiency is eaten up by electricity being more expensive than gas.

>>globul+kN1
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.