zlacker

>>PaulHo+(OP)
Perhaps I am missing something; this product already exists as the Sunamp Thermino.

https://sunamp.com/en-gb/hot-water-solutions-thermino-range/

>>chicke+jq1
It also exists, as described in the headline, as a tank of heated water.

The phase change stuff has positives like taking up less physical space but it's also a much less mature tech than storing hot water.

>>ZeroGr+ev1
Indeed.

In the UK there was a unfortunate trend of ripping out these energy storage devices and replacing hot water tanks with on demand electric hot water heating ( only heat the water you need ). And new builds often have no tanks ( as it saves space in the new tiny homes ).

Very short sighted in my view - a very simple way to store energy and everyone uses hot water directly.

>>DrScie+SF1
They don't work well with heat pumps. Heat pumps lose efficiency as the differential increases, so if you try to store heat in a tank, you quickly drop capacity and efficiency.

Versus resistance, which is exactly as efficient at 0°C and 1000°C, and why those storage heaters used to make sense.

(And storage is directly proportional to temperature differential above interior ambient)

>>coryrc+OY3
Every air-to-water heat pump install will have a hot water tank. So I'm not sure why "don't work well" is the term used.

It is true that heat pumps coefficient of performance drops as the output temperature increases. So you need a proportionally larger hot water tank to store the same amount of energy. So it is fair to say there are tradeoffs. But hot water storage is still a necessary part of most heat pump installs - because peak output of heat pumps tends to be below the heat demand of showers.

>>leoedi+sF5
EDIT: I misread "ripping out these energy storage devices" as https://en.wikipedia.org/wiki/Storage_heater which are basically bricks with nichrome wire.

You're right, of course heat pump water heaters use tanks to smooth out DHW demand, but that same thing isn't feasible for space heating.