Revisiting hot water heat pumps

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#3389109 2-Jul-2025 15:50

alasta:

Thanks Scott for the detailed analysis. It is really helpful.

I'm not keen on taking the 'cheap' route for the reasons noted by the plumber commenting above, so I agree with your final conclusion that it's not really a viable project until my existing appliances are approaching end of life. My home was built new five years ago so the appliances still have a decent amount of life left in them, but in another five to ten years time I will have a go at building a proper business case for the switchover.

Your point about heat pumps having cooling capability is notable. My place gets extremely hot in the middle of summer, so I would probably need to get some form of cooling if I ever get pets.

On cooling, my heat pump's purchase last year was primary (almost entirely), for summer cooling. The upstairs of our house has enough heat drift upstairs from the old lounge heatpump that not much more winter heating is needed.

I know that in Auckland, A well designed house should not need air conditioning, but my house is far from that, and ends up way to hot upstairs.

Ment I could get rid of my old hose out the window portable aircon, and I can work at home more, saving petrol. But I suspect still a net increase in energy use, but massive comfort gain.

Sadly is seems this issue has not been solved in modern homes, as regulations require heating, but not measures to prevent overheating.

www.nzherald.co.nz/nz/homeowners-hit-with-soaring-bills-as-they-struggle-to-cool-new-auckland-townhouses/

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Quite suppressed such a modern house in NZ has a combined gas hot water and space heating via radiators. Common overseas, but I have never seen one on NZ.

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The house being only 5 years old, would put me off also. Those appliances are far from end of life, and anything you touch on the interior (like ripping out the radiators) is going to have quite an impact on the Aesthetics.

Scott3

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#3389111 2-Jul-2025 16:00

Mik:

Interesting how some on here say “reputable brands’, and then Midea, like somehow they are disreputable because they aren’t F&P (someone who will never get a penny from me)

FWIW, they are the largest HVAC and appliance-maker on the planet, by some margin. In business since the 60s, they have a US$40B annual turnover, are the world's largest producer of industrial robots and appliances.

I spent the last 20 years prior to 2020 living in Asia - Midea is a hugely respected brand. Many of those “reputable brands” are made in Midea’s factories. Panasonic heat pumps are rebadged Midea. Toshiba is owned 80% by Midea and almost all products are made by Midea-group factories

Don't let a lack of familiarity and price snobbery make you think they are ‘cheap’ or low-quality

I didn't mean to criticize any of the cheaper brand's.

On the word "Cheap", it simply means low priced.

I used the term "Reputable", rather than high quality, as I am not in a position to be able to comment on the Quality of Midea, Vouge etc.

A lot of brand Reputation is inherently to do with Familiarity.

And for some reason here the Price differential's are massive here Vouge Induction cooktop for $250 where f&p charges $1700.

Midea heat pump hot water for half the price if other options etc.

Would be really interested in learning the reason why for the above if somebody is willing to dive into it.

Handle9

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#3389114 2-Jul-2025 16:15

Mik:

Handle9:

There is also no such thing as a carbon negative appliance just as there is no such thing as creating energy.

There's no such thing as a pedant, either.

Oh, wait - It seems I'm incorrect about that, too.

Your defensiveness here shows the complexity of carbon reduction. It's not simple and can't be done with handwaving. It's made worse by nonsense marketing terms like carbon negative appliances.

Gradually replacing EOL appliances with lower emission appliances doesn't produce the same dopamine hit as throwing out perfectly serviceable equipment but it is generally more effective. That doesn't help appliance manufacturers sell their new stuff though so they won't suggest it.

Scott3

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#3389128 2-Jul-2025 17:04

PolicyGuy:

An alternative analysis is to regard this as an ethical rather than economic issue.

Instead of asking "can I get an acceptable return on the money invested?", ask "what can I afford to do to reduce my carbon footprint?". In my case, part of the answer was to de-gas my house.
Yes I am probably SKIing (Spending the Kids' Inheritance) to some degree, but I hope I'm also contributing - in a tiny way admittedly - to giving the same kids (and grandkids) a chance of living in a more habitable future.

Yesterday, the maximum temperature in Spain & Portugal was over 44°C and it's only June ...

It's great that you have invested the funds in moving off gas, and it is something everybody will need to do in the next 20+ years. Most notably moving your demand to electric gives the industry a signal to spin up some more renewable power project's

But my take is there is not a ethical issue in waiting for gas appliances to reach their end of life.

There is a sink cost (both environmental and financial) of the existing appliances. Replacing them early has both a financial and environmental cost.

The marginal unit of power in NZ is typically Gas, Currently we are generating 439 MW pf power with gas:

www.transpower.co.nz/system-operator/live-system-and-market-data/generation-fuel-type

Much more efficient to burn the gas directly for heat than it is to Burn it in a ~35% efficient open cycle, or ~56% efficient open cycle turbine power plant. For use in a resistance heat load. (heat pumps would likely yield a bit more output compared to burning the gas directly).

Also with our cap and trade carbon system, emitting less doesn't drop overall emissions, it just reduces the price of carbon at the cap and trade auctions. (That said there is some value to this, a low carbon price makes reducing the cap more politically palatable, and reduces the social Burdon on those in a position with little choice to emmit (the large family living rurally, sharing a thristy people mover etc).

Mik:

That's a misconception.

You're never going to reduce or claim that carbon back - going to a carbon-negative appliance as soon as possible at least has a chance to offset that CO2 emitter, somewhat, where hanging on to that old gas appliance just adds more pollution to the environment

It's like the argument of hanging on to your old, cheap car, because it costs X in carbon to build it and you need to get that value out - the best thing you can do is recycle it as soon as you can and get something greener. That's the only way of getting the carbon back

The carbon cost comes from the premature replacement of the appliance. It sure costs in carbon to build a car, heat pump, induction cooktop etc.

If it is worth replacement comes down to balance of the production carbon footprint, and the in use footprint.

For a car, an EV has about a 60% lower lifetime carbon footprint, so if doing regular amounts of mileage, replacement would give a decent reduction in carbon footprint.

https://www.eeca.govt.nz/insights/eeca-insights/lifecycle-assessment-of-electric-vehicles/

But as a counterpoint, if there was a gas water heater at a batch that only gets used 2 weeks a year, then it would likely not be worth the carbon cost of building and installing a flash heat pump water heater to replace it. The latter could we not pay back in carbon terms over it's usefull life.

WWHB

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#3389152 2-Jul-2025 19:56

k1w1k1d:

Hi WWHB.

What are the four brands that you recommend?

Apricus, Reclaim, Envirosun, my back up brand is Rheem. My suppliers for the first 3 allow me to swap out for a brand new unit if I can’t fix it.
Rheem do a 280 litre option called the Ambipower and are a distributor for an exceptionally good system called Sanden. In my opinion this Sanden is probably the best system available on the market.

Saor Alba

WWHB

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#3389159 2-Jul-2025 20:12

Mik:

Interesting how some on here say “reputable brands’, and then Midea, like somehow they are disreputable because they aren’t F&P (someone who will never get a penny from me)

FWIW, they are the largest HVAC and appliance-maker on the planet, by some margin. In business since the 60s, they have a US$40B annual turnover, are the world's largest producer of industrial robots and appliances.

I spent the last 20 years prior to 2020 living in Asia - Midea is a hugely respected brand. Many of those “reputable brands” are made in Midea’s factories. Panasonic heat pumps are rebadged Midea. Toshiba is owned 80% by Midea and almost all products are made by Midea-group factories

Don't let a lack of familiarity and price snobbery make you think they are ‘cheap’ or low-quality

My opinion on Midea for hot water heat pumps is based on the ones branded as Ecospring sold through plumbers merchants. They may say ecospring on the unit itself but come with the exact same instruction book as the Midea one sold at trade depot. The instructions even call them Midea units. These are definitely the same units with different branding. Also for some reason sold at a much higher price.

Working for a previous employer these were the only units we installed, multiple failures and customer push back. My previous employer originally liked they so much he installed one on his own home, lasted 5 1/2 years before becoming an expensive electric cylinder. Not one of these units has a working heat pump on them anymore, the longest lasting one was 7 years. We had a 300 litre unit that had been repaired by refrigeration engineers twice but became so noisy they just couldn’t live with it anymore. There is no way we were that unlucky and managed to buy every faulty one sold locally.

Also not a fan of Steibel Eltron units as I know people who have been left without hot water for extended periods due to no parts to repair the faults in the country.

Panasonic hot water heat pumps won’t be rebranded Midea

My previous employer now no longer installs Hot Water Heat Pumps and sub contracts all installs to me.
I only install them if I can warrant and service them and know I will get supplier back up.

Saor Alba

Kickinbac

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#3389521 3-Jul-2025 20:52

Sanden and Reclaim are essentially the same unit made by Chofu in Japan. They have slightly different controls. The Sanden has the controller in the outdoor unit while the Reclaim is external with WiFi control option.

I recently installed a Panasonic CO2 hot water heater pump. This uses the Reclaim controller. No WiFi option though as the Panasonic doesn’t have Modbus.

Most of the CO2 domestic HWHP heat pumps originate from Japan from their Eco-cute development and have been around for about 20 year.

Daikin are releasing a domestic CO2 HWHP in NZ in the next few months.

WWHB

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#3389547 4-Jul-2025 06:46

The unfortunate thing about the new Daikin one is that it is coming with an internal hot water cylinder

Saor Alba

Aucklandjafa

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#3402023 12-Aug-2025 11:31

I've scanned through this thread, does anyone know real world energy consumption (KW per day/year) of a HP hotwater system for two people.

Seeing what any savings would do from ditching mains infinity unit.

Cheers

Kickinbac

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#3402061 12-Aug-2025 13:36

Aucklandjafa:

I've scanned through this thread, does anyone know real world energy consumption (KW per day/year) of a HP hotwater system for two people.

Seeing what any savings would do from ditching mains infinity unit.

Cheers

My real world consumption for 2 adults and 2 teenage children - 2.66 kWh per day, this is based 132 days from 1st April 2025 to 11th August 2025

Before the upgrade, our average on a medium pressure hot water cylinder is about 10.8 kWh per day. Sorry that is based on a couple of months last year.

This is only based on data since HWHP installed at end of March 2025. I use a Shelly PM1 to log the power use.

As for hot water use by teenagers its hit and miss between not showering for days and spending an hour in the shower! 🙄 This data is hard to gather.

I'm not doing anything special with running times, it runs when it needs to.

This is a Panasonic CO2 HWHP, split type with 250 litre cylinder.

Perchy

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#3405841 20-Aug-2025 13:18

We are looking at getting a heat pump water heater for our new build. I'm hoping to have one which I can ideally integrate with Home Assistant in some way to optimise energy usage with our solar etc. Seems like Rheem units overseas can be integrated with an ESP32 using the RJ11 diagnostics port which would be ideal, but I can't see anything about this on NZ models like the ambipower 280e. Anyone know if this can be done, or whether there are any other good HPHW that can be integrated?

boland

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#3406118 21-Aug-2025 13:50

Perchy:

We are looking at getting a heat pump water heater for our new build. I'm hoping to have one which I can ideally integrate with Home Assistant in some way to optimise energy usage with our solar etc. Seems like Rheem units overseas can be integrated with an ESP32 using the RJ11 diagnostics port which would be ideal, but I can't see anything about this on NZ models like the ambipower 280e. Anyone know if this can be done, or whether there are any other good HPHW that can be integrated?

Hello, fellow HA user :) I was/am in the same boat. Couldn't find any that has an official HA integration, or an open API.
I just did another search and Rheem is an option without ESP32, via Econet?

https://www.rheem.com/econet/

https://www.home-assistant.io/integrations/econet/

My main goal was to turn it on when my solar was generating power. E.g. the Calitec one has a relay input for that, which can be easily automated. But that wouldn't give me any insights, just the ability to turn it on when needed.

StructureDr

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#3406141 21-Aug-2025 15:03

WWHB:

k1w1k1d:

Hi WWHB.

What are the four brands that you recommend?

Apricus, Reclaim, Envirosun, my back up brand is Rheem. My suppliers for the first 3 allow me to swap out for a brand new unit if I can’t fix it.
Rheem do a 280 litre option called the Ambipower and are a distributor for an exceptionally good system called Sanden. In my opinion this Sanden is probably the best system available on the market.

What are the benefits of the Sanden system? Is it the higher efficiency they offer? We're embarking on a project that has a Rheem Ambipower specced - but see that these are not stainless, whereas the 300l Sanden system is I think.

Is there much cost difference between the two?

Perchy

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#3406198 21-Aug-2025 15:49

boland:

Perchy:

We are looking at getting a heat pump water heater for our new build. I'm hoping to have one which I can ideally integrate with Home Assistant in some way to optimise energy usage with our solar etc. Seems like Rheem units overseas can be integrated with an ESP32 using the RJ11 diagnostics port which would be ideal, but I can't see anything about this on NZ models like the ambipower 280e. Anyone know if this can be done, or whether there are any other good HPHW that can be integrated?

Hello, fellow HA user :) I was/am in the same boat. Couldn't find any that has an official HA integration, or an open API.
I just did another search and Rheem is an option without ESP32, via Econet?

https://www.rheem.com/econet/

https://www.home-assistant.io/integrations/econet/

My main goal was to turn it on when my solar was generating power. E.g. the Calitec one has a relay input for that, which can be easily automated. But that wouldn't give me any insights, just the ability to turn it on when needed.

I don't think NZ Rheem models come with the econet thing, as I can't seem to see it mentioned on any product pages.

I found an ESPHome package for local control of Rheem devices, which you can DIY pretty easily with an ESP32. Search for 'ESPHome Econet' as my account seems to be too new to post links. The water heater just needs to have an RJ11 diagnostics port, but I can't seem to find any mention of these on NZ models either.

WWHB

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#3406219 21-Aug-2025 18:04

The Sanden is more expensive and takes a little bit more work to install due to it being a split system.
As far as I am aware there is no monobloc style system with a stainless steel cylinder.
The Sanden would outperform everything else on the market (excluding the reclaim and Panasonic units). The CO2 units have much faster recovery and would be cheaper to run than anything thing else available. The Sanden can only be supplied and installed by approved suppliers, I would check with Rheem about a local one to you (the reason I say that is that I am approved but don’t appear on the list on their website). In my case the Sanden is a bit cheaper, quite a bit cheaper than the Reclaim. The Panasonic is mid price point between the 3 units. I had a Sanden at my place for the last few years, I recently moved home and my biggest regret was not taking that system with me.

Saor Alba

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