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.

I love the idea BUT I’m not sure it’s something that’s available right now.

Have a look at this link FD 👇

https://www.hydrosol.com.au/heating-cooling-advice-design/all-electric-solar-hvac-design/hydronic-heat-pumps/integrated-heating-cooling-hot-water/

I found the article to be quite informative. I am getting the impression that the technology is currently limited in scope.

One Task at a Time

Keep in mind that your heat pump can only perform one task at a time so if you are using it for both heating, cooling and/or pool heating, it is better to have a separate hot water heat pump.

Also, factor in rebates offered for stand alone heat pump water heaters, which are not offered for integrated systems. Hence, the net installed price difference is actually negligible between integrated systems and separate hot water and hydronic systems. Space is the key factor.

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

I love the idea BUT I’m not sure it’s something that’s available right now. Have a look at this link FD 👇 https://www.hydrosol.com.au/heating-cooling-advice-design/all-electric-solar-hvac-design/hydronic-heat-pumps/integrated-heating-cooling-hot-water/ I found the article to be quite informative. I am getting the impression that the technology is currently limited in scope. One Task at a Time Keep in mind that your heat pump can only perform one task at a time so if you are using it for both heating, cooling and/or pool heating, it is better to have a separate hot water heat pump. Also, factor in rebates offered for stand alone heat pump water heaters, which are not offered for integrated systems. Hence, the net installed price difference is actually negligible between integrated systems and separate hot water and hydronic systems. Space is the key factor.

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.

freediver wrote on Oct 9^th, 2023 at 11:51am:

Lisa Jones wrote on Oct 9th, 2023 at 10:40am: I love the idea BUT I’m not sure it’s something that’s available right now. Have a look at this link FD 👇 https://www.hydrosol.com.au/heating-cooling-advice-design/all-electric-solar-hvac-design/hydronic-heat-pumps/integrated-heating-cooling-hot-water/ I found the article to be quite informative. I am getting the impression that the technology is currently limited in scope. One Task at a Time Keep in mind that your heat pump can only perform one task at a time so if you are using it for both heating, cooling and/or pool heating, it is better to have a separate hot water heat pump. Also, factor in rebates offered for stand alone heat pump water heaters, which are not offered for integrated systems. Hence, the net installed price difference is actually negligible between integrated systems and separate hot water and hydronic systems. Space is the key factor. 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.

Ok. Next question: Has this been successfully implemented before/elsewhere? I’m thinking maybe in Germany?

No idea.

You need to consult with the Sacred Electric Eel.
Deity and Totem of all Electrical knowledge.

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

...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.

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.

     https://i.postimg.cc/pVqLv8tp/Screenshot-2023-10-09-at-23-49-41-ey-Jid-WNr-ZXQi-Oi-Jjb250-ZW50-Lmhzd3-N0-YXRp-Yy5jb20i-LCJr-ZXki-Oi-Jna-WZc-L2hl-YX.png

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

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.

You would need a couple of compressors.It wouldn't be efficient to use just one.The AC would need bigger compressor.

You could get heat from fridge/freezer coil
Since AC isn't on as often it could limit how much heat you get from that coil in cooling mode.

I don't think you would get enough heat doing it this way for hot water.

You would also need a storage tank cobined with solar hot water on roof with maybe gas or electric (from solar panels instead of using battery) or even firewood backup.

What you're suggesting is using this for input into storage tank which sounds feasible i doubt you would get enough hot water from that alone.

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Storage tank internal

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Quote:

I don't think you would get enough heat doing it this way for hot water.

Why not?

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

I don't think you would get enough heat doing it this way for hot water...

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.

AusGeoff wrote on Oct 10^th, 2023 at 8:42pm:

Baronvonrort wrote on Oct 9th, 2023 at 11:19pm: I don't think you would get enough heat doing it this way for hot water... 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.

I am not suggesting they point a reverse cycle air conditioner at the hot water system and hope for the best.

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

Quote: I don't think you would get enough heat doing it this way for hot water. Why not?

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.

Baronvonrort wrote on Oct 10^th, 2023 at 9:16pm:

freediver wrote on Oct 10th, 2023 at 8:52am: Quote: I don't think you would get enough heat doing it this way for hot water. Why not? 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.

So use a bigger one.