@andy_e 
Have you been in contact with your council yet? I would suggest you do or by going ahead you could be risking things by moving back to the fence and the "noisy" Daikin and be faced with expensive repositioning AND even losing the grant for not obeying the requirements!

@npru
I am waiting on the revisit from Octopus to look at the new location - that includes a noise assessment - While the unit is noisier I believe there are factors such as direct line of site to nearest inhabitable room that are taken into account and therefore maybe some benefit taken from its new position. However my way forward is based on this assessment - following which I may need to discuss further with the council.  However, until the noise assessment is completed in the new position I won’t know.

@mikeh, thanks a lot for the video. I found them very informative (especially for would-be heat pump owners). I can see that you had a much smoother Aira installation journey than I did. FYI, I have nearly the same system (8kW external, 250L indoor, 40L buffer, 8 replacement + 1 new radiators, 8.46 kW heat loss calculated by Aira). My journey started in mid-August:

• Day 1: Parts arrived with some missing; external conduits arrived in the wrong colour. The team spent only over half a day to rip out the old system. To be fair, there's quite a bit to be removed; it's a system boiler set-up with a header tank in the loft. The boiler was inoperational, so that was a bit easier. They left early because they didn't have some required parts to continue.
• BTW, not a lot of drilling was needed because the indoor unit went where the previous cylinder was and they reused the existing wall opening for the boiler's flue for the two pipes connecting to the external units. Most of the previous pipework was reused.
• Day 2–3: installation of the external unit and electrics. A bit of a wait for 2 extra Aira plumbers to come to lift the indoor unit upstairs (needed 4 ppl). As you were, I was surprised at the amount of pipes, the two expansion vessels, and the size of the buffer. I asked to have the buffer up in the loft (right above the indoor unit) as agreed with the Aira salesman, but the plumbers were hesitant about the required work. One (on a rather large size) even had the cheek to tell my wife that it was not possible. I even contacted the Aira designer to confirm and insisted that it be done; they finally relented.
• Day 4: The electrician has done his installation, but he could not start the indoor unit. He suspected a faulty PCB but didn't have a spare one to test, planning to come back the following day with one. The plumbers carried on with the pipework and hanging radiators.
• Day 5: The plumbers came back and finished all their installation but not the electrician. So, the system cannot be commissioned. No lagging was done to the pipework above the indoor unit; I guess they wanted to make sure the system worked before covering everything. The plumber left with a promise to come back sometime next week to commission the system.
• Day 23: After lots of chasing up, a new plumber and the original electrician visited. The electrician redid all the connections and managed to turn on the indoor unit. The plumber then commissioned the system and showed me the Aira app. He also took notes of everything that had been left unfinished so he could order the required materials to be there another day - it sounds reasonable.
• Day 33: A technician came with the thermostat and spent over an hour but the connection kept dropping. We had to resort to leaving the thermostat close to the indoor unit, not an ideal place.
• Day 73: After a lot of complaints over email with a list of issues and things to complete, an engineer turned up with just one thing on his job list: to push the temp sensor on the buffer vessel in properly to fix the overheating issue I mentioned in a previous post. I discussed the thermostat issue, he kindly stayed for over an hour to try a new thermostat he'd got in his van. The end result was good as I can leave the thermostat in the hallway as originally intended.
• Day 78: Two Aira engineers turned up and fixed a single thing on the list: replacing the grill of the external unit because it was spoiled by the expanding foam they used to fill the wall opening.
• Day 86: One engineer came and did all the remaining items (lagging the pipework above the indoor unit and in the loft, extending the condensation drain pipe so water is not puddling around the external unit). I paid Aira on the day after all this was done.
• Day 106: I received the hand-over pack by email, which included an "ASHP Commission Checklist" dated Day 5 (when the whole installation should have finished) while the system was actually commissioned on Day 23. On this checklist, they ticked off "System Balanced" – If this means the balancing of the radiators, none of it was done. It made me doubt if the other items on the list were correctly recorded. Another discrepancy is the Flow Temp in the checklist is 45º, while that in the Heat loss design and the MCS certificate in the same email is 55º.

So, I just want to add my story here as another data point on Aira's service. Overall, I'm happy with the system I have and its performance over the last few cold spells. My house is on 20º consistently whatever the outdoor weather. Even with the lack of radiator balancing, I don't have any cold spots; I suspect it is because the existing heating circuit in my house is already adequate.

However, as you can read above, there is a lot to desire from Aira's logistics, work planning, and communication. If you're lucky to have a good team as Mike did, your installation may be smooth (especially now, assuming they sorted out all the teething issues, such as the buffer's temp sensor). If you're unlucky like me, it may take a lot of effort to get things done correctly. I found Aira was willing to fix issues, but their planning and communication have a lot of room for improvement. Me withholding the payment until everything was done may have been a strong incentive, and even so...

This last point has made me a bit wary about their 15-year guarantee promise. I can only hope that they will still be in business and stand by their promise (and sort things out much faster).

After reading all that posts here,  I have just started my conversation with Aira. The heat loss assessment has been scheduled for just before Christmas. Hopefully, should get a full quote and detailed design in the new year. Then, we can decide and move ahead if it all works. I have been trying my infrared experiment and can already see that we have cut down a lot of the emissions from gas we would have consumed otherwise to heat one of the bigger open plan living kitchen dining rooms. DHW is already on off-peak times (and solar when it's not awful like how it's now!) using the immersion heater and that has cut a lot of emissions too. But, if we want to get rid of gas completely, probably heat pump is the only option.

The Aira heat pump definitely looks great, so that's obviously one deciding factor. Noise is another consideration, but luckily the location for the heat pump would be at least 10 m from the neighbour and there is no line of sight to any of their windows. But, most importantly for me at least, it's the system performance and potential emissions savings. The sales person was telling me that the heat pumps operate at high temperature up to 65 degrees, and may be we can even start with that high temperature option without changing all the radiators. Later if we decide to change the radiators they can tweak the flow temperature. But, I would like to get the changes done as part of one installation if possible and maximise the COP.

Does anyone here have any experience with the high temperature option of Aira heat pumps please? 

@chandykris my advice would be to change any radiators recommended to run on a low flow temperature. Ours is designed at 45° with an outside temperature of -2°. A lot of the time our flow temperature will be in the 30’s and the house is still lovely and warm at 21°get it right first time and enjoy being emission free and lower bills. In my opinion the sales person is the weak point as they are limited in knowledge and nearly always overspec. Once you have had your heat loss calculation done then you will have a proper speced system

@bromide Thanks for the advice, doing it once but properly is my preferred approach too.

Octopus and Heat Geek initial quote (from EPC only) came in at around 8 KW. Another installer came in at 14 KW heat pump, but had made too many mistakes and I don't trust their calculations. I took the recent cold snap as an opportunity to run the whole house at 18 to 21 degrees and check how much heating would we use for the whole day if we went down the heat pump route. Their calculations are way off from what I found. We usually turn off unused rooms, so didn't have proper figures until this November cold snap.

Hopefully, Aira come in with a reasonable size heat pump, good system design and quote.

@trungdong is your Aira heat pump the Aira-branded one? And if yes, what is the name and model please?

@editor Yes, it's their "Aira Generation 1" 8kW model:

Outdoor: HPO-AW-8-230V-1.5
Indoor: HPI-AO-250-1.5

Some technical information for my model.

The much awaited Aira assessment is done and have received an all-inclusive quote from them. Interestingly, they have gone for a 6kW model. Not surprised as our house is only 11 years old and has pretty good insulation, glazing and loft insulation. Even my own calculations on Heat Punk suggested something similar. Just indicates how oversized our first quote was from an installer (14kW). HeatGeek rough estimates for a property of similar age and around 180sqm size means 6kW sounds reasonable, maybe slightly undersized.
Aira's quote is double that of Octopus who were suggesting a 8kW heat pump, subject to a full survey. It's decision time, but inclining towards Octopus despite the 15 year comfort guarantee from Aira.

Posted by: @chandykris

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It's decision time, but inclining towards Octopus despite the 15 year comfort guarantee from Aira.

This is purely speculation, but I’ve been struck by how many credible, top-tier installers I’ve spoken to recently who’ve all said something similar. A 15-year guarantee sounds great on paper, but it’s meaningless if the company isn’t around to honour it. Aira does have significant financial backing, so that’s worth considering. It’s also interesting that your Aira quote is so much higher than OE’s. There must be some key differences to weigh up.

When you’ve made your decision, please share your thought process with us because it’ll be valuable for others in the same position.

@editor Sure, will do. I will also post our installation journey when we go ahead.

This might explain things