I had a Daikin 9kW installed in June 2024.  I have been battling Octopus for it to be swapped for an 8kW since about October 2024.  My primary issue with the 9kW has been noise.  Secondary issues are overheating the house in moderate outside temperatures, low SCOP and the shockingly bad installation quality.  I followed the typical 9kW owners path.  Had it installed and right away noticed how noisy it was.  It woke me up for the first overnight DHW Cycle and I wondered what on earth was happening.  I soon re-programmed that for during the day and stopped it reheating DHW at all.  I also noticed that despite the incredible racket it was constantly overshooting inside temperature.  There was not a weather cure low enough.  I installed an ESPAltherma and started monitoring it.  Went on the open energy forum and facebook and found that there were other 9kW Daikin owners with the same issues.  I had gas smart meter data and whole house temperature records from before the install so I calculated that the worst case gas boiler output extrapolated to -3.2 was 5kW.  This seemed very low.  I started plotting the heat pump output alongside the gas output on the same chart.  The dots were aligning.  Even though it was early days it looked like the heat pump heat output would also extrapolate out to 5kW.  I presented this analysis to Octopus along with my prediction that the winter's SCOP would be 3 for CH at the end of October 2024 with my first request for a swap to an 8kW unit.  This was declined.  As the winter's data accumulated the heat output and SCOP were following the prediction.  It was mind boggling that my actual heat loss could be 5kW and not the predicted 7.5kW.  More research revealed that ACH might be the issue.  I did a heat punk survey and googling to see what typical air exchanges might be for a 1988 house.  This gave a good indication that ACH might be the issue.  I commissioned a door blower test and it revealed that my house is actually very air tight.  More so than most new builds.  With the correct ACH figures, both heatpunk and MCS give around 5kW.  All 4 methods gave pretty much the same value!  And with default ACH my MCS and heatpunk surveys broadly agree with the Octopus figures.  So all in all, even though I am not a qualified heat loss surveyor, I can state with a very high degree of confidence that my actual heat loss is 5kW at minus 3.2.  This in my mind now all makes sense, the heat pump is a noisy model anyway, but it is made worse, has poor SCOP and is very hard to control properly because it is 78% oversized for the heat load.  I've been feeding this information as it has built up to Octopus each time re-requesting the replacement but so far they have refused.  The measures that have been taken include:

• Re-piping in the loft to stop resonation of the ceiling over a bedroom - moderate improvement but still noisy at 31l/m
• Removing the drip tray and building a soakaway
• 3 Daikin visits
• Many Octopus visits
• Repeated Survey - same result
• Further upsizing of radiators
• Latest outdoor unit firmware
• Pump speed set to 60%

Issues not relating to the noise include

• 2 leaks during install - Resolved
• Clogged filter causing shut down twice - the system was not flushed - Resolved (through cleaning filter - not flushing)
• Radiators not balanced - Resolved by me
• Two burnt carpets - Resolved with £200 good will gesture
• Burnt Skirting - Not reported
• A section of lagging missing - twice, hidden inside the soffit so I didn't realise they hadn't fixed it the first time - Re-reported, fix being arranged
• Tap hammer, occurring after install, there was a PRV before the install with cold feeds balanced - Only just reported, not resolved
• Heating of volumiser during DHW.  Resolved as part of the loft re-pipe
• External pipe lagging looked rough from day one but after a year has multiple gaps with the foam exposed, finishes short of the soffit board with a bit of silicone seemingly floating in the air.  Recently reported - Offer to resolve
• One of the 28mm primaries is connected to the old 22mm boiler feed that loops out and back - Recently reported - offer to investigate
• Internal lagging gappy and loose in places - Offer to resolve

Of course I would have expected some of the issues in the second list in such a big job.  But given the overall catastrophic failure to install the correct sized heat pump and the sheer number of issues with the install I am including them in any complaints so that it is known just how bad the overall experience has been.

When I was woken up on Sunday at 6am this week I had had enough.  Over the next few days I started firing off emails to greg@octopus.energy notifying of external escalation and my handler, serving a formal rejection.  I opened a section 75 claim with my credit card provider, also informing my handler.  Also posted on the unofficial Octopus heatpump facebook where one of my posts was picked up by TJ who DM'd me.  

Yesterday I received a phone call followed up with the following offer:

I wish to present details of our final position.

• Engineer to return and rectify the pipe insulation, to the external primary pipe work and internally at the cylinder. Additionally fit external pipe trunking to further minimise future risk to external insulation. This will be provided free of cost.
• We will not be liable for the replacement ASHP unit, from 9kw to 8kw as requested.
  We complete our site surveys in accordance with industry standards and in good faith of the information available at this time. The currently installed heat pump is performing within the estimated range and the manufacturer has deemed the noise level within normal parameters.
  We are however willing to replace the ASHP with an 8kw unit at a discounted price of £1950, should you wish.
• As also discussed, I would be happy to send a senior technical delivery engineer to compile a report of any other concerns that you may have with the completed works. Once received I will review and make suggestions for any improvements I deem appropriate.

I think the multiple 9kW to 8kW swap-outs fall in to two categories.

1. After the customer has kicked up a huge fuss, Octopus re-do the survey and realise an error caused the heat loss to be just over the threshold for the 9kW and do the swap for free
2. Again, after a huge fuss, they re-do the survey but get the same or worse, in this case they offer the replacement at cost.

Now I believe this is technically and morally wrong, I am being to asked to pay for a mistake that is either caused by Octopus themselves or poor regulation.  It is damaging to their reputation, Daikins and the heat pump industry as a whole.

The sound intrusion is mostly qualitative in my case. I have a sound meter and it doesn't appear to breach the limit. It's the type of noise from the compressor and the fact it penetrates into the house which is the main problem.  Then there are the flow noises in the primary pipes over my bedroom.  The compressor is just very rough sounding.  The rapid changing of the frequencies and the coming in an out of resonance at different frequencies also a big factor. Then there are clicks and whooshes as it changes the valving around at each end of the defrost cycle. If it was a constant hum like a fridge or a boiler it would be far less intrusive and of negligible disruption to sleep. I should say that it is significantly louder than a fridge or boiler which is what Octopus claimed. It is however the combination of ramping up and down and sometimes holding steady. Some slow ramps, some sudden. All highly audible from my bedroom.

Plenty of people say the 9kW Daikin is loud (This includes Daikin and Octopus engineers), a few say it isn't. Many say the 8kW Daikin is quiet and those who have had the swap say it is much quieter.

What should I do?  It seems I need to take on Octopus and the industry to get them to pay for the rectification entirely.  I can afford the 2k and it is quite tempting to get this resolved with out a big continuing fight throughout the winter whilst being regularly woken up at 6am.

Any thoughts appreciated.