Another interesting development, Aira is now offering a heat pump electricity tariff and optimising heating to take advantage: https://www.airahome.com/en-gb/energy-tariffs

It isn't specific about rates, but they say it is through Octopus, so it looks very much like this just a rebadged Cozy tariff. The advantage is that the Aira controls will optimise the operation of the ASHP to maximise the heating in the three cheap slots and minimise during the high price 4-7 slot.

I wonder if Octopus are doing something similar with their Cosy ASHP?

I'm not a fan of the Cosy tariff, as it is only cheaper than price cap for 8 hours, whereas Agile is usually cheaper for 21 hours. However, if Aira are doing some optimisation on top, maybe that would narrow the gap in cost?

I've found the actual tariff rates, hidden in the small print explaining how they calculate the savings they claim:

"In the calculation for Aira Zero, energy costs are compared between a boiler and a home equipped with an Aira Heat Pump under the Aira Zero tariff. It factors in a yearly electricity consumption of 3,375 kWh for the heat pump priced at a blended average rate of 17.43 p/kWh which is the average from 40% base rate at 22.65 p/kWh, 52% dip rate at 11.10 p/kWh, 8% peak rate at 32.84 p/kWh. And 3,000 kWh for your appliances at 17.19p/kWh which is the average from 38% base rate at 22.65 p/kWh, 54% dip rate at 11.10 p/kWh, 8% peak rate at 32.84 p/kWh.​"

I think those probably are the Cosy rates, though no doubt they are using the cheapest region, so a bit lower than Cosy in my region.

So, they reckon only 8% of the heating would be in the 3 hours of peak rate. That seems fairly conservative, given that 3 hours is 12.5% of a day. I would have thought the ASHP need not be heating at all for 3 hours.

And they reckon 52% of heating in the 8 hours of dip pricing, which is 33% of the day, so this is primarily where they are getting the optimisation, by cranking up the ASHP for these 8 hours. I wonder how much the house temperature would fluctuate as a result? If it was, say, 23C at the end of these boost periods, that would be too warm for me.

And how much would the SCOP be impacted by running the ASHP at higher power in those 8 hours than if it were running steady for, say, 21 hours, which is what I'd do with Agile?

@ivanopinion To me this all goes to demonstrate that both Cosy and Agile are even more useful when battery storage is available. As you say, using the cheapest hours to boost temperature is not the best way to run a heat pump - for economy or best COP. On another note, looking at the daily average price during the cheapest periods for Agile, I think the overall average rate is still some pence above the cheapest fixed rate for Cosy - but I shouldn’t cross post! Regards, Toodles.

Thanks again to everyone for their comments, and especially to @mikeh for his detailed feedback on the Aira experience. His comments and those of the community are always very useful.

Yesterday I received a visit from the Aira consultant and I have decided to give the green light for the heat pump installation. They will give me the 6KW outdoor unit and the 250 litre indoor unit. The installation date is 9 September. In my case, the heat pump will be used for hot water and radiant heating in a 105 square metre house in Bussolengo, a small town near Lake Garda. The final cost, in ten years and after government subsidies, will be 6k (€). The first price they offered was exorbitant, but the second offer, to promote the launch of Aira in my region, was much more reasonable and so I accepted it. For me, this is an investment and the 15-year guarantee was too attractive to choose another brand, even though I know there are many more trustworthy ones out there, but if something happens after the first two years, I'm on my own and that would be a big loss for the tokens I'm putting into this game. Fingers crossed, I'll update you on the installation as soon as possible.

I have the Aira 8KW unit (with a 250L indoor unit and 40L buffer) commissioned today. Aira still needs to come back to finish a few minor issues, but the heating and hot water seem to work OK so far. If you have any questions about the system, I'll try to answer them.

Update on my Aira Heat pump. We are still waiting for a date for an installer to come back in fit the missing thermostat. We have been told by Aira that they at least have the thermostats in stock in the UK now. They should be scheduling an new engineer visit next week. Unofficially I know they have been training the engineers how to fit them this week.

The heating has been coming on this week when it dropped cold outside. Without the indoor thermostat, the heating will come on whenever it drops below 15 degrees outside, which so far has resulted in a 24'c hot house. Even though a few radiators do not come on at all, probably due to no balancing taking place yet. TRV's lowered to get the temperature down in the house. The system has used a fair amount of energy but I don't know how much is too much and I have no idea what the COP is because there in no info in the app :(. I measured the flow temperature on the hottest radiator which was 52'C. I'd not run the boiler that high at this time of year, even before the larger radiators were fitted. I assume the weather compensation needs adjusting but that is not something that is adjustable on the app. I will wait until the thermostat is fitted then raise these issues with Aira if the flow temp remains high. 

We went away for 2 weeks the week after the install was completed and set the heat pump to away mode on the app. Unfortunately the heat pump continued merrily heating the water every day and wasting money. I noticed the high energy usage via my octopus energy app, so I contacted Aira while I was away to see if they could push some sort of shut down request to the heat pump, but they were unable to connect to the heat pump. It turns out that they were unable to connect to the heat pump because 3 days after leaving home the RCD on my consumer unit tripped, so no power to the WIFI. Return home to a fridge and freezer full of rotten food. 3 electrician fault finding visits later, there was a break in the electric cable on the ring circuit to the the dining room and utility room(new cylinder location). Now resolved by separating the ring circuit into two separate circuits. Now there is no proof that Aira have drilled into a cable in the wall in the utility room. The electrician could not trace a live screwhead, but it's a fairly big coincidence!

@mikeh Oh Dear! This install is not going very well for you is it?😒 I do hope the tripped RCD can be shown to be due to their work too. As an advert for a new product, things haven’t gone well have they? Regards, Toodles.

Posted by: @editor

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@ivanopinion where are you up to and have you made any further decisions?

Just to round off some loose ends from my contributions to this thread, in the end I decided not to go with Aira. I realised that the various compromises and limitations would niggle at me, so I decided to pay the extra for my local Heat Geek. I don't expect to recoup the extra install cost in electricity savings; if cost was the deciding factor I would have gone with Aira. So, I'm paying extra because I think I'll get a system that doesn't rankle with me.
HG are just finishing the install, which looks good so far, though I guess I won't know how well it works until December.
The things that put me off Aira don't mean I won't be recommending them to friends. Most people won't want to be able to tweak their weather compensation curve or even understand why you might want to do so. Nor will they want to see feedback of what their ASHP is doing. They won't know or care why it is suboptimal to have an unnecessary buffer or an outdoor temperature sensor that has to be at the back of the ASHP. Essentially, I'm paying more for Heat Geek because I did too much research (on sites like this), which means I understand how Aira are simplifying and compromising in ways that I think make sense for the bulk of the market. Most people just want something that replaces their gas boiler, keeps them warm, costs not much more than a gas boiler to install and costs no more to run. Aira is aiming to deliver that.
 

Posted by: @mikeh

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Update on my Aira Heat pump. We are still waiting for a date for an installer to come back in fit the missing thermostat. We have been told by Aira that they at least have the thermostats in stock in the UK now. They should be scheduling an new engineer visit next week. Unofficially I know they have been training the engineers how to fit them this week.

The heating has been coming on this week when it dropped cold outside. Without the indoor thermostat, the heating will come on whenever it drops below 15 degrees outside,...

I was shown a dangling probe (copper head, black wires) coming out from the top of the indoor unit, and I was told it measures the indoor temperature shown in the Aira app.

I was also told that only a few thermostats are available in the UK for testing/training, and a couple hundred from Poland are currently stuck at UK customs; they would visit customers to set those up once available, hopefully soon.

After your update, I just realised that the app does not offer an option to turn off the hot water. I can only hope their cylinders are well-insulated.

 

@trungdong It rather sounds as though the product was launched before units were available and the fitters had had the appropriate training on Aira specific parts. I suspect that ‘Sales’ were just too eager to promote a product not yet ready for installation nationwide. Toodles.

@ivanopinion Good perspective! Apologies if this is somewhere else on the forum but which brand did you go for? I'm guessing Vaillant or Viessmann since you go with Heat Geek?

Yes, Vaillant. But Aira were willing to give me that if I paid an extra £1k, which would still have been cheaper than HG.
To be fair, a chunk of the price difference came from HG being the only firm that proposed a pipe route that is way, way neater than any other. They got a builder in to remove some tiles on a mini-roof, to route the pipes through the roof void. There’s only a few metres of visible piping.