There’s another thread about the Octopus 9 which has needed anti-vibration feet rather than be flat installed on a solid slab. Perhaps any outside noise would be reduced by such feet for you? The 12 must surely be noisier?

Posted by: @judith

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There’s another thread about the Octopus 9 which has needed anti-vibration felt rather than be installed on a solid slab. Perhaps any outside noise would be reduced by such feet for you? The 12 must surely be noisier?

I should think so, I thought that pretty much universal practice was to install heat pumps on AV feet and I am surprised not doing so was even considered!

I think the issue is being missed here. I've had a Cosy 12 for about a week and the fan noise is really really noisy when working hard. Used a mobile app at a range on 1m and it measured 76db. Even the installers were surprised at the volume that was not reflected in the estimate from the survey or the spec on the Octopus website.

@bigfish Sorry to hear that. 

I would suggest the first step is to get the installer back (preferably before you pay) to look at the noise.  Antivibration feet/better pipework decoupling may be necessary or it may be a fault.  However please note that heat pumps are at their noisiest when its really cold outside which until about a week ago it was.  If you provide a bit more detail we may be able to make some suggestions.

Thanks @jamespa - the wife is pulling her hair out. Installed last week, side of a detached house, free standing facing neighbours fence 1.5m away. Appreciate it is cold but when running full pelt generates 76db regularly when measured by a mobile app which I accept isn't likely to be 100% accurate. Rural location so limited background noise. The MCS 020 was based on the listed output of 61db giving 36.9 at the neighbours upstairs window. Installed under permitted development.

@bigfish Very similar situation here. I measured with the Octopus recommended decibelX app, and the noise also reaches over 70db here.

I'm not in a rural place (south-west London), and it's very loud.

Ours is also causing some kind of issue with the piping/plumbling as there's a low (180Hz - 200Hz) drone at various points through the day, also there's a kind of pulsing or chugging sound whenever someone runs a tap in the house.

All in all a complete nightmare.

@editor I've had the installer come on Wednesday, and he said it's a buffer AND a volumizer 🤨, and had to be installed because it was easier to position there than a volumizer (?).

He turned the secondary pump all the way down to its lowest setting and balanced some of the radiators so that the house would heat more evenly. 

All this made no difference to the level of noise. 

The outside unit is noisy, even when seemingly not on full blast, and inside there's a strange intermittent drone at about 190Hz, that I thought was coming from the volumizer, or secondary pump, but the buzz/drone is still there when these two components appear to be off.

Thank god I haven't paid them yet. I told them to send another guy on monday, and if that doesn't fix it I'm gonna have to start thinking about getting them to rip the bloody thing out. Which, given the amount of money involved (and them having already collected the BUS grant), will be a long and stressful process.

Posted by: @razz

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also there's a kind of pulsing or chugging sound whenever someone runs a tap in the house.

Thats very unlikely to be anything to do with the heat pump, the water system is essentially completely separate.  Changes may have been made to the water system when the heat pump was installed however, so it may be related to these changes, most likely increased water pressure if a previously loft-fed system, which is generally a good thing but can occasionally cause water hammer

@razz @bigfish I'm not trying to diminish the issue with my comment that very cold weather is when its going to be most noisy, just add some context. 

I think Cosy 12 is pretty new and it may be its 'pushing the boundaries'.  Is it just a Cosy 9 uprated I wonder?  My advice is to put pressure on Octopus with this one.

There are people complaining about the noise of their Cosys.  Not just the blown air noise but some form of low frequency noise that they seem to be sensitive to.  I can confirm that at cold temperatures, the Cosy 9 is quite loud - the air being expelled through the fan is audible in the bedroom approximately 4 metres away through triple glazing.  It doesn't wake me up but I am aware of it when going to bed and waiting to fall asleep.  Once temperatures are above approximately 5c, then it quietens down a lot.  I don't seem to suffer from any low frequency noise.  The only other noise, is the flowing water through turned down TRVs in a couple of rooms, including the bedroom.

Posted by: @razz

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@editor I've had the installer come on Wednesday, and he said it's a buffer AND a volumizer , and had to be installed because it was easier to position there than a volumizer (?).

Technically, a buffer tank and a volumiser are the same piece of metal until you pipe them in. Once it’s installed and connected, it is one or the other. It cannot be both. So the explanation you’ve been given is, frankly… worrying.

Once you look at how yours is piped (as @jamespa has already identified from the photos) you have a buffer tank. Full stop.

The comment about it being installed "because it was easier to position there than a volumiser" makes no sense at all either. A volumiser is not a different object that’s harder or easier to place. It’s usually the same tank, just piped differently.

And I have no idea what Octopus think a "volumiser" is in this context, because what you’ve been told doesn’t line up with basic system design. 

I’ve heard a few reports about the Cosy 12s being very noisy. One from an engineer. 

Octopus may have a problem on their hands.

Posted by: @razz

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@editor I've had the installer come on Wednesday, and he said it's a buffer AND a volumizer 🤨, and had to be installed because it was easier to position there than a volumizer (?).

He turned the secondary pump all the way down to its lowest setting and balanced some of the radiators so that the house would heat more evenly. 

All this made no difference to the level of noise. 

The outside unit is noisy, even when seemingly not on full blast, and inside there's a strange intermittent drone at about 190Hz, that I thought was coming from the volumizer, or secondary pump, but the buzz/drone is still there when these two components appear to be off.

Thank god I haven't paid them yet. I told them to send another guy on monday, and if that doesn't fix it I'm gonna have to start thinking about getting them to rip the bloody thing out. Which, given the amount of money involved (and them having already collected the BUS grant), will be a long and stressful process.

Posted by: @razz

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also there's a kind of pulsing or chugging sound whenever someone runs a tap in the house.

Sorry to hear that.  To sum up the advice you have received so far.

1. The buffer tank is a buffer tank,.  It does also serve to increase system volume (so performs the function of a volumiser also) but that doesn't change the fact its a buffer tank.  This will almost certainly increase your running cost by 15% and the secondary pump is almost certainly only needed because its there.  Its almost certainly the case that it would be better replumbed as a 2 port volumiser and the secondary pump removed .  They should be required to provide a no nonsense, no BS justification for NOT doing this.  If the secondary pump is part of the noise problem this would eliminate it.

2. The noise when someone turns on a tap is NOT connected to the heat pump itself albeit that it occurred simultaneously.  It will almost certainly be occurring because you now have mains pressure hot and cold water to all outlets, whereas previously you have low pressure.

The norm when heat pumps are installed is to upgrade low pressure (loft fed) hot/cold water systems to high pressure (mains fed).  Mains fed systems are generally better and pretty much standard in new builds.  It makes for better showers, means that water from all taps is potable, allows a wider range of fittings and means hot water reaches distant taps quicker and flows faster. 

Possibly reducing the pressure a bit will help (there is an adjustable valve near the cylinder) or it may be that there is some blocked air so draining and refilling the DHW/Cold water system will eliminate it.

3. The outside unit noise needs investigation.  My guess is that either better isolation (is it on vibration isolating feet?) or some internal mods to separate components that are amplifying the sound will help.  Unfortunately tracking this sort of thing down can be difficult so you may want to/have to allow them a few attempts.  It does sound like they might have some systemic problems with this unit so they should be actively looking at them.

I think you will struggle to get them to take it out unless you give them a fair crack at solving the problem, however I would personally put the position writing the position and make it clear that you don't accept it as it is and reserve the right to require them to remove it.  Of course they may just decide to swap it out for the Daikin which I believe they also supply.

Hope that helps.