This is an idea I had from the solar system thread. A fridge and freezer, as well as an air conditioner, are a heat pump. They have a cooling element inside, and a heating element outside.

Most hot water systems are simply heaters. They convert electricity to heat. But if you use a heat pump instead, they consume less electricity. Such a system would have a heating element inside and a cooling element outside.

So, why not combine them into one? Use a single heat pump and run the fridge, freezer and air con off the cooling element, and the hot water system from the heating element.

Lisa Jones wrote on Oct 9^th, 2023 at 10:40am:


That assumes a conventional arrangement like a reverse cycle air conditioner with one element actively heating or cooling what you want to heat or cool and the other wasting the heat or cool to the atmosphere. With this arrangement, you run it backwards to change from heating to cooling.

No idea.

freediver wrote on Oct 9^th, 2023 at 9:53am:

Sounds good, but would never work in practice.
Reverse cycle air conditioning doesn't work that
way, as one coil is always hot, and one coil is
always cold;  note the reversing valve.

    

Storage tank internal

Baronvonrort wrote on Oct 9^th, 2023 at 11:19pm:

Agreed.  "Sucking" the heat out of the external atmosphere
would never approach enough to heat water to, say, 70ºC.

Hold your hand in front of the average reverse cycle A/C
when it's in its heating cycle, and you'll find the temperature
of the airflow will be around 25ºC after passing through the
condenser coil.

freediver wrote on Oct 10^th, 2023 at 8:52am:


Domestic fridges embed hot coils in case they haven't been put on the back of fridge for decades.Not enough heat to be plausible.

If you had a commercial size cool room you might get some heat i doubt it would be enough for hot shower.

With split system AC is it a unit in the room or a much larger system ducted to every room? The bigger the AC unit the more you will get i doubt it's enough for a hot shower.

What happens when it's colder and you don't use the AC? Would you turn AC on in colder weather to get a tiny bit of hot water?

Qlders might be OK with warm showers those who live in colder parts look forward to hot showers. When i spend time in the bush eradicating ferals i do look forward to a hot shower when i get home it's a simple thing in life you miss it when you don't have it.

A heat pump system is the go for electric hot water.
Reverse cycle AC is the cheapest form of electrical heat.

Those who light fires for heating should consider upgrading to efficient wood burner to also supply hot water which can also be pumped to radiators.

They can run a solar hot water system on roof with this for hot water in the warmer months. Another option is put a 1-2Kw electric element in storage tank and power that from solar panel.

I like my hot water at 60+ deg.