hot water heat pumps

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ajw

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#323088 24-Oct-2025 08:31

I'm single and live alone in my own place and have gas hot water cylinder which was installed 12 years ago but due to the high cost of natural gas and line charges I'm thinking of getting rid of the gas and replacing with a heat pump hot water cylinder.

For the extra you pay for a heat pump hot water installation are they worth it especially as I said I live alone. Looking forward to any comments.

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#3427663 24-Oct-2025 08:41

A sparky mate said to not bother and just get a normal electric cylinder as the failure rate is quite high with heat pumps (outside of warranty); you just end up using the built-in element on a hp unit that costed you 3x more than a standard hw cylinder.

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#3427667 24-Oct-2025 09:27

I suggest you read through some older threads for some insights

Gree WHIO Hot Water Heat Pump - User Feedback

Anyone have a Econergy Hot Water Heat Pump Split System?

Hot Water System. Gas v Heatpump

Revisiting hot water heat pumps

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timmmay

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#3427674 24-Oct-2025 10:29

I just had an AI do a payback calculation on a hot water heat pump. Assuming $7000 installed price and 10kw of power used per day (that's 5 showers per day) the payback period is 10 - 13 years - if they last that long. Given the lack of reliability I wouldn't think they'd be worthwhile for any household that has less than about 10 showers per day.

What might be a better idea is one of those systems that puts a panel on the roof that directly heats the hot water from the sun - not solar electric. They are very efficient. I haven't looked at the cost of those though.

Spyware

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#3427675 24-Oct-2025 10:40

timmmay:

What might be a better idea is one of those systems that puts a panel on the roof that directly heats the hot water from the sun - not solar electric. They are very efficient. I haven't looked at the cost of those though.

Neighbour had one of those. One frosty morning I was lying in bed wondering what the sound of trickling water was. Over the years there has been various leaks and has since been removed after being completely replaced in earthquake repair.

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timmmay

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#3427686 24-Oct-2025 11:48

Spyware:

Neighbour had one of those. One frosty morning I was lying in bed wondering what the sound of trickling water was. Over the years there has been various leaks and has since been removed after being completely replaced in earthquake repair.

Interesting. I wonder if the more modern ones last longer. They seem like a good idea, directly using the heat from the sun rather than converting it to electricity at 25% efficiency then using the electricity.

hamish225

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#3427696 24-Oct-2025 12:54

timmmay:

I just had an AI do a payback calculation on a hot water heat pump. Assuming $7000 installed price and 10kw of power used per day (that's 5 showers per day) the payback period is 10 - 13 years - if they last that long. Given the lack of reliability I wouldn't think they'd be worthwhile for any household that has less than about 10 showers per day.

What might be a better idea is one of those systems that puts a panel on the roof that directly heats the hot water from the sun - not solar electric. They are very efficient. I haven't looked at the cost of those though.

If you have to replace your hot water heater anyway like I did because it gave up on life, a resistive electric mains pressure hot water cylinder is going to cost about 4k installed anyway, at least according to the quotes that I got when I put in my HPHWC. So your payback period calculations could be quite different if you factor in only the additional cost between what you would get otherwise and the hot water heat pump.

So really, the hot water heat pump only costs an extra 3-4k and costs so much less to run!

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Kickinbac

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#3427722 24-Oct-2025 14:17

timmmay:

I just had an AI do a payback calculation on a hot water heat pump. Assuming $7000 installed price and 10kw of power used per day (that's 5 showers per day) the payback period is 10 - 13 years - if they last that long. Given the lack of reliability I wouldn't think they'd be worthwhile for any household that has less than about 10 showers per day.

What might be a better idea is one of those systems that puts a panel on the roof that directly heats the hot water from the sun - not solar electric. They are very efficient. I haven't looked at the cost of those though.

A problem with solar thermal hot water is that you get too much hot water in summer and almost none in winter, particularly if you get an overcast and rainy period. So no hot water bill in summer and an increased electricity bill in the winter months. Plus there is still a pump and controller to maintain.

Hot water heat pumps are usually not economical for lower hot water users but need to look at the math and see what the cost difference is between a HWHP and a standard electric cylinder when converting.

There are smaller HWHP models, Ecospring has a 200 litre version. Heck, Trade Depot has a Midea 170 litre HWHP for $1699 with a 5 year warranty! At that price, it could be worth the risk!

Or OP can look at electric hot water cylinder with solar PV panels for energy cost reduction. There are diverters that will send excess generation directly to the cylinder.

Aucklandjafa

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#3427725 24-Oct-2025 14:23

timmmay:

I just had an AI do a payback calculation on a hot water heat pump. Assuming $7000 installed price and 10kw of power used per day (that's 5 showers per day) the payback period is 10 - 13 years - if they last that long. Given the lack of reliability I wouldn't think they'd be worthwhile for any household that has less than about 10 showers per day.

What might be a better idea is one of those systems that puts a panel on the roof that directly heats the hot water from the sun - not solar electric. They are very efficient. I haven't looked at the cost of those though.

No way a HP hot water cylinder is using 10kw/day - more like 2kw (a large standard cylinder would use 6kw/day)

richms

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#3427746 24-Oct-2025 15:12

I was looking at swapping out for one as I want to get rid of the indoor one and its coming up 18 years old now so probably about time to leak being that its an enameled one.

Trade depot have a midea for $1699 - only 170l but that will be fine for just me in the house and I can always get a second if I start to have flatmates again.

At the moment I have the 300l electric one and am never running it out with just me there, it did run out sometimes when I had flatmates in the past.

Trying to get a plumber to give me a price on moving the pipes thru to the back veranda and if the old valves are still usable or not. Plumbers are worse than builders for not responding.

Richard rich.ms

Kickinbac

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#3427772 24-Oct-2025 15:52

Aucklandjafa:

timmmay:

I just had an AI do a payback calculation on a hot water heat pump. Assuming $7000 installed price and 10kw of power used per day (that's 5 showers per day) the payback period is 10 - 13 years - if they last that long. Given the lack of reliability I wouldn't think they'd be worthwhile for any household that has less than about 10 showers per day.

What might be a better idea is one of those systems that puts a panel on the roof that directly heats the hot water from the sun - not solar electric. They are very efficient. I haven't looked at the cost of those though.

No way a HP hot water cylinder is using 10kw/day - more like 2kw (a large standard cylinder would use 6kw/day)

My average over the last 7 days is 2.3 kWh

RunningMan

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#3427779 24-Oct-2025 16:20

Aucklandjafa:

No way a HP hot water cylinder is using 10kw/day - more like 2kw (a large standard cylinder would use 6kw/day)

You mean kWh not kw? Either 2 or 3kW would be the most common element power.

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#3427789 24-Oct-2025 17:09

RunningMan:

Aucklandjafa:

No way a HP hot water cylinder is using 10kw/day - more like 2kw (a large standard cylinder would use 6kw/day)

You mean kWh not kw? Either 2 or 3kW would be the most common element power.

You didn't quite understand what they were saying, yes they used the wrong units, but they said a HWHP shouldn't use 10kwh per day of energy. Nothing to do with element size.

WWHB

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#3428075 26-Oct-2025 19:05

Payback for a 1 person household would be a long time, the more use the better. They are more reliable that you would think, I have installed loads and haven’t had 1 breakdown.

Saor Alba

timmmay

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#3428222 27-Oct-2025 13:43

I meant we use 10kwh of power with a standard cylinder, that is what I put into the AI for the calculations.

Good point about incremental cost. That takes the payback period to between 3 and 5 years but that's a very approximate calculation based on a likely flawed AI prompt. Makes it seem viable anyway.

richms

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#3429626 31-Oct-2025 14:33

Last day of the special so pulled the trigger on the cylinder. If they do a better deal tomorrow I will have to get in and cancel the order before they ship it. Still no joy on plumbers. Dont have a website if you're not going to email back.

Richard rich.ms

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