@vsmith1 @toodles January has been challenging for heat pumps with cold and wet weather. It's reassuring to see that our COP numbers are similar. As long as it is over 3, I think it is acceptable.

I also set the overnight cool down by -2ºC between 23:00 and 7:00.

It's great that Aira continue to add features to the app. Our 8kW efficiency figures are:

Has anyone got any information on how/why they justify a buffer tank in their install?  Everyone seems really happy with the install and running so I assume the buffer isn't an issue but given the general feeling that buffer tanks shouldn't be used by default this is the one piece of their installation that I find a bit strange. 

@andrewj Our installers fitted am LLH; their justification for fitting this efficiency reduction is that ‘It ensures that the heat pump sees a constant load and the actual secondary circuit flow rate is less critical making it much easier to achieve a constant Delta T.’ Not sure that this is the full story but suspect that, as mentioned on this hub numerous times, it reduces the chance of engineer call-outs. 😒 Regards, Toodles.

@toodles So that would imply what I thought (perhaps I'm too cynical): it is put in to separate problem responsibility between the heat pump and the secondary circuit.  Although in the case of Aira, who install both sides and presumably are responsible for warranting both, I don't think that counts for much (as opposed to, say, a Vaillant heat pump and a local installer.)  Is it much of an efficiency hit or do they have it technically sussed?

@andrewj In my case, I would put any shortcomings down to the installers but fortunately for us, our system is working very well. I took the measure of optimising the things that the installers run out of time to do😉 for myself. I let them roughtly balance the radiators during a very warm end of day in February (before they all went off home or to the pub or whatever) as I knew there was no way the system would be optimised that afternoon!

I also played with the LWT and at that time, I had to let the MMI controller do what it could to run well. I gradually improved the settings for the WC and then come the following autumn, I had Homely smart control added.

In between times, I bought 4 of the temperature probes and ‘calibrated’ them, (I bundled all the probes together, let them stabilise overnight and noted the disparity in the 4 sets of readings). I taped the probes on all four pipes entering and leaving the LLH and covered each with a few layers of insulating aluminium coated sheet. I then gradually adjusted the secondary pump speed to achieve minimum disparity between the flow in and flow out to the pump - and likewise between the return flow and the LLH return to the heat pump circuit. Regards, Toodles.

@andrewj Well, not everyone. My experience would probably be the one anti heat pump brigade would be keen to highlight. The product is great, the installer who came is really good. But, I don't think Aira have their operations under control.

It's day 9 and my installation is still ongoing. Not because it's a complex installation, but rather because they decided to again send only one engineer on-site this week. With a three storey house and 15 radiators, the one engineer on-site can only run around so much to check for leaks. There was a massive leak in my study and just missed the electrical sockets by sheer luck. It could have been a total disaster. I am having to help the installer with lifting and positioning a large radiator as there's no way he would be able to lift a 70 kg radiator and install by himself. And to top it all, they sent me an invoice to pay for a system that's not even commissioned!

Day nine gone, the heat pump is still not commissioned. There's a sensor problem and there's no electrician onsite to help the lead engineer. Now, they won't come back until Thursday and won't be commissioned until day 11.

Not sure what options are there to explore, complain to MCS, trading standards, Ofgem. Personally, I shouldn't have fallen for the 15 year warranty and should have gone with Octopus or Heat Geek. If their service is as bad as the installation experience, the warranty is not worth the hassle.

@chandykris Sounds like a pretty poor state of affairs.  Hopefully once it is in and commissioned it will work fine and this will drift into a bad memory lost in the mists of time.  I now have to decide between Octopus or Heat Geek for an install - I think I'll leave Aira and not complicate it further.  I don't have all the details yet but I think the juggle will be between cost, confidence and heat pump model!

Thanks @andrewj. Hope my bad experience didn't put you off. Others in the forum have had good experiences, so maybe mine is just an odd one out. 

I should have done what Toodles and others had suggested. Lower the flow temperature post installation. Let Octopus design the system at 50 degrees flow temperature, but upgrade the radiators myself at an extra cost and then lower the flow temperature. Well, hindsight is a wonderful thing!

@chandykris sorry to hear this, I hope that progress picks up and Aira will sort your system.

Aira managed to send an engineer at 5:30 pm today and it took a while, but thank Higgs Boson, we have heat! It was up and stunning around 8:30 pm starting with hot water. Then heating kicked off and the house is slowly heating up. Really surprised how quiet the unit is, I can hardly hear it working from the sun room just 1.5m away. 

Still loads to do, lagging everything, sorting out some joints, cleaning up everywhere, close the boiler flue hole. But, at least the heat pump is commissioned. Like Andrew said, maybe this will just be a bad memory in the mist of time.