Revisiting hot water heat pumps

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66 posts

Master Geek
+1 received by user: 2

#3476261 31-Mar-2026 17:35

Question to anyone with a sanden unit - how loud is yours?

I'm getting around 45dB at over 1m away with a low frequency vibration coming from the connection end. The kind of frequency that you hear straight through the wall. Rheem are trying to claim it's normal, they've replaced the water pump but if anything it is worse now.

Video

Facebook seems to indicate that anything louder than the fan noise is too loud, just after some more evidence as I feel like Rhheem are trying to convince me I'm wrong for wanting this thing to be as quiet as advertised (36db).

Obviously noting that it only really runs during the day so it isn't a major, but when you pay close to $13k I think I'm within my rights to demand perfection.

WWHB

57 posts

Master Geek
+1 received by user: 48

#3476338 31-Mar-2026 19:55

meeekael:

Question to anyone with a sanden unit - how loud is yours?

I'm getting around 45dB at over 1m away with a low frequency vibration coming from the connection end. The kind of frequency that you hear straight through the wall. Rheem are trying to claim it's normal, they've replaced the water pump but if anything it is worse now.

Video

Facebook seems to indicate that anything louder than the fan noise is too loud, just after some more evidence as I feel like Rhheem are trying to convince me I'm wrong for wanting this thing to be as quiet as advertised (36db).

Obviously noting that it only really runs during the day so it isn't a major, but when you pay close to $13k I think I'm within my rights to demand perfection.

I have installed quite a few Sanden Units, in my opinion it is the best system available on the market. I have never had a noise complaint from an install. In fact they are so quiet you can feel the cold draft from the unit before you can hear it. Any chance it’s how it’s mounted that’s causing this. I have multiple wall mounted installs as well, that are just as quiet

Saor Alba

meeekael

66 posts

Master Geek
+1 received by user: 2

#3476339 31-Mar-2026 20:09

Pretty standard install from what I can tell. The sound is very much originating from where the connections are. I can feel the vibrations under the cover where the pipes are. I think it's quiet-ish when it first turns on, so when the rheem tech visited (I wasn't home) he triggered it, listened to it for 10 minutes then left claiming it was fine.

I've got time on Friday so will pull the cover off myself and have a poke around once it gets up to volume.

Any chance you're going to be around Feilding any time soon? Would love to grab you for a second opinion!

WWHB

57 posts

Master Geek
+1 received by user: 48

#3476378 1-Apr-2026 07:15

Install looks standard to me, rubber between the metal feet and plastic mounting feet would help with absorbing vibrations. Not saying that will fix it. When I wall mount them the wall mounts come with rubber pads that I bolt through. That install will be quite rigid being fixed down to the footpath. The unit would most likely vibrate when running and with your install there is nothing to absorb this. Please note this is just my opinion but I do believe rubber pads of some type will help.
Unfortunately I am Napier based and probably won’t be able to take a look for you

Saor Alba

Kickinbac

487 posts

Ultimate Geek
+1 received by user: 104

#3476530 1-Apr-2026 12:01

I think from the video that the noise is the compressor, it's little hard to tell.

Check the filter / strainers, they may need a clean out. These are at the water connections. https://www.facebook.com/groups/MyEfficientElectricHome/posts/5652857411425322/

It could be some resonance in the panels. I'd give it a slap/tap and see if it goes away or the pitch changes. Obviously not hard enough to damage the unit!

Just a thought, sometimes there are packers under the compressor, to stop movement in transit, that need to be removed when installed. But I doubt this as usually on these type of systems the installer only needs to get to the water and electrical connections on the side panel.

Also, you could try rubber feet like these to isolate the unit but really this should not be necessary. Fairly common to source from refrigeration suppliers like LIMS, Real Cold, Pattons etc https://lims-hvac.co.nz/products/anti-vibration-mounts-6868-045-sumo b

Can you get hold of the Sanden technical support directly or are you going though the plumber? There is very little serviceable in the field for the refrigeration system. A technician can change circuit boards and the pump but anything refrigeration or heat exchanger is usually a return to supplier for fixing or a unit swap out.

meeekael

66 posts

Master Geek
+1 received by user: 2

#3478413 6-Apr-2026 12:49

These are the two pipes that are vibrating/loud. For the first 30 mins or so its honestly pretty quiet and bearable, at around an hour though it steadily ramps up to what it is in the video. I've had fish tanks in the past and it's a really similar sound IMO to when there was air in the filter pump/impellor. I've cleared the drain a few times, a ran an AIR cycle on the controller and there's been no improvement.

After I heard how quiet it was running this morning I had considered letting Rheem off the hook, but its back being as loud as it ever was again now, 2 hours later.

Jiggling or rocking it on the base makes no difference and the sound seems very isolated to those pipes and whatever lives below them (I assume the CO2 compressor or water pump?) so I don't think foam mounts will change it, but can suggest that to Rheem.

Can you get hold of the Sanden technical support directly or are you going though the plumber?

I was dealing with Rheem through Laser, but Laser are over it and out of ideas so now I'm dealing with Rheem directly. - I assume (hope) they are talking to Sanden in the background and aren't just shotgunning it.

Kickinbac

487 posts

Ultimate Geek
+1 received by user: 104

#3478833 7-Apr-2026 14:14

The black round thing looks like the expansion valve. Its hard to know what the sound is, either pump or compressor. Either way it shouldn't be noticeably noisy. You should be able to stand 2 meters away and not hear anything.

I reckon its a swap out if they can't solve with a tech in a couple of visits. Its not like you bought something cheap, Sanden are supposed to be the best out there.

Either through MEEH or direct, contact these guys in Oz as they always seem helpful on MEEH. They may be able to point you in the right direction on what to do. https://pure-electric.com.au/faq/sanden-eco-heat-pump-hot-water?page=1

Loismustdye

952 posts

Ultimate Geek
+1 received by user: 256

Trusted

#3479566 9-Apr-2026 18:41

We are looking at a hot water heat pump as well with our solar investigations.
The contenders from my wife’s work at this stage is the co2 based Panasonic he-um60cr with a rinnai 275 or 340 litre water tank, and the daikin rqwx60zv1a with a 315 litre tank. Likely going the larger tank size with twins entering the teens and the excessive hot water use that comes with that.

the Panasonic sits close to $2k cheaper than the daikon, both similar noise levels (it will be going where the existing infinity system is so a quieter sound level is a must as it’s between the kids 2 bedrooms on the outside).

Does anybody have any experience with either of these 2 units? Both have wifi apps so I will be able to set timers and plans etc.

thanks

Kickinbac

487 posts

Ultimate Geek
+1 received by user: 104

#3481130 15-Apr-2026 17:00

Loismustdye:

We are looking at a hot water heat pump as well with our solar investigations.
The contenders from my wife’s work at this stage is the co2 based Panasonic he-um60cr with a rinnai 275 or 340 litre water tank, and the daikin rqwx60zv1a with a 315 litre tank. Likely going the larger tank size with twins entering the teens and the excessive hot water use that comes with that.

the Panasonic sits close to $2k cheaper than the daikon, both similar noise levels (it will be going where the existing infinity system is so a quieter sound level is a must as it’s between the kids 2 bedrooms on the outside).

Does anybody have any experience with either of these 2 units? Both have wifi apps so I will be able to set timers and plans etc.

thanks

I've got the Panasonic CO2 with a 250 litre cylinder and had it for just over a year. It has no Wi-Fi as wasn't available then. I had the control panel installed inside by our cylinder so I just look at that for the tank temperature.

It's brilliant, highly recommended! I've had no problems and I have no complaints. I've saved good money, average $100 per month saving. Our previous low pressure cylinder was on controlled power so I have actual hot water power use from old bills to compare and I use a Shelly power monitor relay to log what the HWHP uses now. In our house we have 2 adults and 2 teenagers. Current average is 1.9 kWh for the last 30 days so about $0.73 per day for hot water.

The CO2 systems do not need an electric back up element. My cylinder has the electric element wired normally to the controlled power, It's just switched off so if I ever have a fault I can use it. If I ever move I'd consider taking the CO2 unit with me to my new house.

Daikin are fairly new in the market. The $2K difference in price is a lot of power to save, based on my usage that's 20 months extra.

Personally I would not choose the Rinnai as looks like it only has 5 year warranty and use R290 (propane) refrigerant. vs. 7 years for Daikin and Panasonic. There's nothing particularly wrong with R290 but its not quite as good as CO2. And you do pay more for CO2!

Loismustdye

952 posts

Ultimate Geek
+1 received by user: 256

Trusted

#3481672 17-Apr-2026 18:08

Kickinbac:

I've got the Panasonic CO2 with a 250 litre cylinder and had it for just over a year. It has no Wi-Fi as wasn't available then. I had the control panel installed inside by our cylinder so I just look at that for the tank temperature.

It's brilliant, highly recommended! I've had no problems and I have no complaints. I've saved good money, average $100 per month saving. Our previous low pressure cylinder was on controlled power so I have actual hot water power use from old bills to compare and I use a Shelly power monitor relay to log what the HWHP uses now. In our house we have 2 adults and 2 teenagers. Current average is 1.9 kWh for the last 30 days so about $0.73 per day for hot water.

The CO2 systems do not need an electric back up element. My cylinder has the electric element wired normally to the controlled power, It's just switched off so if I ever have a fault I can use it. If I ever move I'd consider taking the CO2 unit with me to my new house.

Daikin are fairly new in the market. The $2K difference in price is a lot of power to save, based on my usage that's 20 months extra.

Personally I would not choose the Rinnai as looks like it only has 5 year warranty and use R290 (propane) refrigerant. vs. 7 years for Daikin and Panasonic. There's nothing particularly wrong with R290 but its not quite as good as CO2. And you do pay more for CO2!

Good to know thanks.

the Panasonic one comes with a rinnai cylinder (the hp itself is a seperate unit according to our pricing for it). My wife’s sparky has nothing but good things to say about the daikin unit, however we may look to forgo a C02 pump and potentially just get a standard hwhp in order to get the initial outlay down a bit.

Kickinbac

487 posts

Ultimate Geek
+1 received by user: 104

#3481841 18-Apr-2026 11:27

Loismustdye:

Good to know thanks.

the Panasonic one comes with a rinnai cylinder (the hp itself is a seperate unit according to our pricing for it). My wife’s sparky has nothing but good things to say about the daikin unit, however we may look to forgo a C02 pump and potentially just get a standard hwhp in order to get the initial outlay down a bit.

I really like Daikin products, for 80% of work I do we would use Daikin. I just haven’t seen or been involved with a Daikin CO2 HWHP yet but am sure they will be good.

Any Japanese origin CO2 HWHP will be fairly similar as they all originate from the Japanese EcoCute R&D programme using CO2 refrigerant, being Sanden, Chofu, Reclaim, Mitsubishi Electric, Panasonic and Daikin here in NZ. These have been in use for 25 years in Japan. It’s not new technology and it’s very reliable and efficient. I just wish that they were more accessible cost wise to New Zealanders as they make so much sense for New Zealand to utilise our electricity generation efficiently. Especially in cold regions and/or there is high hot water use.

boland

569 posts

Ultimate Geek
+1 received by user: 91

#3482926 22-Apr-2026 08:43

We have a Gree WHIO 270L heat pump and I've been checking the temperature when not in use. It drops about 0.4c per hour, which seems high. However, I've also read that this is not a reliable way of measuring temperature loss. Eg if the temp sensor is in the middle, it will stop heating when that is 60c, but there's still cold water at the bottom.

They originally had it installed with the outlet pipe going up first, which could be a reason for thermal loss. They have now remedied that, it goes straight for ~30cm and then down.
This has made no meaningful difference.

Thoughts?

Kickinbac

487 posts

Ultimate Geek
+1 received by user: 104

#3483397 23-Apr-2026 12:39

boland:

We have a Gree WHIO 270L heat pump and I've been checking the temperature when not in use. It drops about 0.4c per hour, which seems high. However, I've also read that this is not a reliable way of measuring temperature loss. Eg if the temp sensor is in the middle, it will stop heating when that is 60c, but there's still cold water at the bottom.

They originally had it installed with the outlet pipe going up first, which could be a reason for thermal loss. They have now remedied that, it goes straight for ~30cm and then down.
This has made no meaningful difference.

Thoughts?

Post a photo of your install then can assess the install and insulation. Standing losses are hard to measure day to day as you would need to not draw off any hot water and understand the outdoor temperature change. The best you can do is make sure all pipes and valves are insulated as best as can be.

boland

569 posts

Ultimate Geek
+1 received by user: 91

#3483729 24-Apr-2026 14:01

@Kickinbac See photos below. Initially the pipe at the hot outlet went up first then down; they've rectified it so it goes straight. It does feel hot to the touch though underneath the insulation, even though we didn't use hot water. Not sure if that's expected.
They had to do it this way as there must be 1 meter before the temp valve.

At one day, it was about 12-15c outside, and we hardly used any hot water, and the measured temperature dropped about 11c. But, I'm not sure how reliable that is; if that sensor is in the middle, the water at the bottom will probably be colder.

Kickinbac

487 posts

Ultimate Geek
+1 received by user: 104

#3483733 24-Apr-2026 14:14

boland:

@Kickinbac See photos below. Initially the pipe at the hot outlet went up first then down; they've rectified it so it goes straight. It does feel hot to the touch though underneath the insulation, even though we didn't use hot water. Not sure if that's expected.
They had to do it this way as there must be 1 meter before the temp valve.

At one day, it was about 12-15c outside, and we hardly used any hot water, and the measured temperature dropped about 11c. But, I'm not sure how reliable that is; if that sensor is in the middle, the water at the bottom will probably be colder.

It looks okay. My advice is that if it’s outside and copper, insulate it! If it’s warm to touch you are losing energy. The first thing I’d do would be to insulate the pressure temperature relief valve and most of the drain pipe below. You probably should also insulate the tempering valve and the cold water pipe below. The colder it is outside the more heat loss. Insulation is fairly cheap.

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