Hot water heat pump

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tech1234

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#251545 30-Jun-2019 15:47

Hope somebody knowledgeable can point me in the right direction.

Recently purchased a property which in the past, probably 10 years ago, had a heat pump which heated the water in the hot water cylinder.

It was removed some years before we bought the property but all the plumbing and electrical wiring is still there in place.

I notice now some relatively cheap swimming pool heat pumps for sale.

Could one of these be used to heat domestic hot water?

If it could, it looks like running costs could be significantly lower for our water heating.

Thanks in advance

Jase2985

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#2267350 30-Jun-2019 15:54

swimming/spa heat pumps dont heat the water high enough for a hot water cylinder to eliminate Legionnaires' disease. you would need a specific unit designed for water heating.

but they are reasonably readily avaliable.

raytaylor

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#2267372 30-Jun-2019 16:48

Would be interesting to know why it was removed.

A plumber in the family has said they have reliability issues and the power savings have not previously been worth it since they dont last very long.

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Aredwood

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#2267393 30-Jun-2019 17:50

Hot water heatpumps have to operate with approx double the temp rise of a heatpump room heater. Meaning that they are noisy, are not as efficient as a heatpump room heater, the compressor won't last as long as it has to run quite hot all the time.

Heatpump hot water only makes sense if you live in a tropical country. Or you have a seasonal demand profile, that means that you need lots more hot water in summer than winter.

Kickinbac

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#2267965 1-Jul-2019 20:22

The NZ made Econergy hot water heat pumps are pretty good and rated well in Consumer magazine. They are separate to the hot water cylinder so can be removed. To justify the cost you probably need to be a high hot water user to get quicker payback. Also be cautious about cost to repair a hot water heat pump (out of warranty) which will quickly suck up any energy cost savings.
They got a bit of a bad reputation a few years ago due to some poor products on the market.

JayADee

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#2269641 4-Jul-2019 07:58

Aredwood: Hot water heatpumps have to operate with approx double the temp rise of a heatpump room heater. Meaning that they are noisy, are not as efficient as a heatpump room heater, the compressor won't last as long as it has to run quite hot all the time.

Heatpump hot water only makes sense if you live in a tropical country. Or you have a seasonal demand profile, that means that you need lots more hot water in summer than winter.

That's interesting. What is the most economical hot water heating option for, say, two people?

E3xtc

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#2269688 4-Jul-2019 08:41

I recall going through this exercise for our household a few years back and decided the standard electric cylinder was just as good as others (in terms of outlay, cost to run, payback period etc)...there was no clear winner, so simplicity and lower cost won out.

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kotuku4

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#2269691 4-Jul-2019 08:53

I investigated heat pump hot water a couple of times, and solar hot water. I was impressed by the ecoenergy reviews in Consumer years ago.

The local installer didn't get back to me with quote, twice. I talked to a medium sized plumbing firm owner and one of his installers that I regularly work with. Got a price on bosch compress system, checked reviews and other online sources.

It worked out to be expensive to install for me, with the unit with compressor outside, needing building consent to run plumbing. All had concerns with longevity of the systems. It seemed to me that the units would be worn out at end of payback period. Same issues with solar hot water, based on their advice.

I already had Solar PV, and found solar diverter to heat conventional hot water cylinder. Later upsized cylinder when it needed replacing, 180 to 270 litre. Currently five of us in modest sized house, one bathroom.

Check out existing plumbing and cylinder, if fairly new insulated cylinder, insulate hot water feed pipe, check thermostat and tap temperature, leaks, your hot water usage.

Should be all good for two people.