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Octopus Cosy 12 Heat Pump Regret: Incredibly Loud, Poor Heating & Constant Hum - Help!

razz · 2026-01-11T11:11:13Z

Hello all,I'm new to the forum. Just had an octopus cosy 12 installed on Friday. Massively regret it already. It's incredibly loud, not looking very cheap, and doesn't heat the house very well. Inside the house there's a constant hum, be it the pump itself, the various pumps, volumizer etc. and the sound of rushing water in the pipes. Utterly tired and depressed.

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L2jad

(@l2jad)

Eminent Member Member

Joined: 3 months ago

Posts: 25

03/02/2026 8:10 pm

Heating came on at first was like tick over very quiet thought great, 5 minutes later warming up two photo’s 74db is about 3ft away from the unit lower than the fan and at side photo a tad deceiving, second is 3m from unit and i’m standing in my garage 64db.
problem is with the wind noise it sounds a lot more . I walked to end of close and can hear it above the rain.

Going to have to turn it off again tonight.

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Harriworld

(@harriworld)

Active Member Member

Joined: 3 months ago

Posts: 13

03/02/2026 8:31 pm

I had a Cosy 12 fitted on 9th Jan and had a Grundfoss (red) pump fitted in landing cupboard with the buffer tank. I complained about the loud buzzing going through the middle of the house. After 2 visits from engineers, the Grundfoss pump was replaced with a Wilo (green) pump and happy to say it is much quieter and do not really notice it now - hope this helps

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Harriworld

(@harriworld)

Active Member Member

Joined: 3 months ago

Posts: 13

03/02/2026 8:34 pm

I am yet to get the issue of noise from the Cosy 12 heatpump resolved. Had 3 post installlation visits, firmware adjustments and settings altered but am no further forward. My neighbours have complained to Environmental Health.

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swwils

(@swwils)

Estimable Member Member

Joined: 7 months ago

Posts: 92

03/02/2026 8:58 pm

@harriworld what have the confirmed? Anything? 😬

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L2jad

(@l2jad)

Eminent Member Member

Joined: 3 months ago

Posts: 25

03/02/2026 9:19 pm

@harriworld its one of my worries with my cosy 12, my nearest neighbour is 20m away, we are all detached houses, i have known my neighbours for 30 years, and i am really worried about upsetting them, the noise level is way above acceptable, could see someone reporting me.

i am turning my cosy off at night as its not fair. Glad it’s not cold.

People don’t understand the noise level measured to the actual sound of the noise its a mental strain, stress and tension levels in doors are indescribable and its only been 5 days for me.

I honestly think octopus should stop installing these until they sort out the unit and at least get customer feed back once sorted. Anybody getting a cosy 12 installed currently needs their head examining !! Just so hard to explain the noise and to be honest i never thought i would feel the cold air 10m away from the unit as the fan points up. We go out the front door and whoosh very cold air hitting you.

I do hope they sort you as hopefully mine will get sorted at the same time, not sure how long i am willing to sit this out, had a £17 electric day yesterday as everything is now from the grid as batteries empty by 11am. My bills were around £2.10 including charging the car plus gas at around £5 a day!!! Close to trebling!!

🤔

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LivingGreen

(@livinggreen)

Active Member Member

Joined: 3 months ago

Posts: 7

03/02/2026 9:51 pm

@harriworld not sure if it would help but we've hired one of these:

https://firstfence.co.uk/hire-acoustic-barrier

to try and reduce the impact on the neighbours while we wait for the noise to hopefully be resolved. Drops the noise by about 8-10dB for us at 1m in front of the heat pump. Think there's a few companies that do them, just that one had a depot we could pick them up from.

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Harriworld

(@harriworld)

Active Member Member

Joined: 3 months ago

Posts: 13

03/02/2026 11:41 pm

@l2jad So sorry you are suffering so much and I genuinely empathise as my neighbours are suffering. Is your heatpump running all night? My understanding is that it ramps up when it needs to heat water or get the house to temperature and if your house temperature drops too low at night it will really ramps up in the morning- it should be keeping your temperature level. Who have you contacted at Octopus to complain about this, can I ask?

This post was modified 3 months ago by Mars

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Harriworld

(@harriworld)

Active Member Member

Joined: 3 months ago

Posts: 13

03/02/2026 11:42 pm

@livinggreen thanks for that, I'll look into it

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L2jad

(@l2jad)

Eminent Member Member

Joined: 3 months ago

Posts: 25

03/02/2026 11:57 pm

@harriworld it’s with the octopus technical team in Ni at the moment my lead installer raised it when he commissioned the system, he could hear how bad it was. Even when it’s .1 of a degree from target it is goes full pelt. At night i am having to stop it running by setting a low fallback temperature. You can hear the pump during the day over all daytime noise, dead of night being very rural its unbearably loud and stands out.
i can’t have it that loud overnight no
one csn sleep.

missed a octopus call tonight but they were closed when i called back will call in morning hopefully its about this and not them just giving me the invoice!

This post was modified 3 months ago by L2jad

This post was modified 3 months ago by Mars

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Harriworld

(@harriworld)

Active Member Member

Joined: 3 months ago

Posts: 13

04/02/2026 7:57 am

@l2jad You need to lodge a formal complaint and get a reference number. Also write email to Greg@Octopus otherwise your complaint will not be properly looked at

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LivingGreen

(@livinggreen)

Active Member Member

Joined: 3 months ago

Posts: 7

04/02/2026 3:06 pm

Just been told there's a firmware update coming for all units this week - some units may already have it

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L2jad

(@l2jad)

Eminent Member Member

Joined: 3 months ago

Posts: 25

04/02/2026 7:49 pm

Right had a call with their chief design lady today, long chat about problem, lovely lady, fiddled with my system from their end, very quiet, I’m going to run it properly tonight to see if it remains this quiet, definitely fan speed.
shame it wasn't like this to begin with but hats off to octopus in dealing as quickly as they have!!! Hopefully this will get rolled out to all cosy 12 users.
as you can tell i’m feeling totally stress free, so happy fingers crossed. Thank you to you lot a lot of reassurance when needed.

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