@wally I should also have said that we are retired, so need the house warm all day, and set the stat at 21C with a set back to 17C overnight.

Posted by: @editor

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it’s all app controlled and optimised by ML and AI

Seriously?  So 'our heat pumps just work, we don't know how, but trust us they do'. 

That sounds like a red flag of the highest order!  No sorry that is a red flag of the highest order.

@downfield Likewise we are also retired and want a warm house throughout the day. 19c seems to keep us comfortable. I have been advised not to lower the temperature at night but to keep a constant temperature 24 hours.

@wally can I just check the obvious- the kWh usage you've quoted is definitely just for the ashp and not whole house? Reason for asking is that the figures you quote [if using an average cost of 26p per kWh- I appreciate I do not know the specific details of your tariff] for Dec seem to be around the £300 mark, which in your initial post you infer is your total bill?

As for the Aira unit and their preference to keep customers rather in the dark (unfortunate), I wonder if there is backdoor access to this unit via home assistant if you were that way inclined to get some data from it. Google suggests there might be several other Aira owners asking about this, and signposting to the dedicated facebook group for potential solutions.

You also mention the discrepancy in your room temps which might be resolved via some balancing, or simply opening up the lockshield a bit more for the radiator in the room that is too cold? Worst case the radiator may be undersized for the room which Aira should rectify, one would hope. Proper balancing of a system is another rabbit hole (and entirely different to how I approached it when we had our gas boiler having made a start on checking this myself over the last couple of days) but suffice to say, as has already been suggested- highly improbable the installers would have done this properly, due to the time it takes to do it properly.

@benson

Thanks for responding and for your advice.

The kWh hours usage I mentioned was for the entire house. For the ASHP in isolation it was 928 kWh for the month of December.

Alas I am not a Facebook fan and have no account. Although I am aware other Aira customers are gathering data using Home assistant my concern regarding that is the possibility of voiding the guarantee with Aira by possible interference with the system.

Balancing the radiators is something I had thought about but wasn’t sure what difference it would make. In saying that I may ask Aira to do that for me.

In fairness to Aira we were really pleased with how they went about the installation. They took 4 days to do the work.

Posted by: @wally

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The kWh hours usage I mentioned was for the entire house. For the ASHP in isolation it was 928 kWh for the month of December.

i'd say your usage isn't outrageous then. You'll probably find peaks of £300 in Dec will mean an average energy cost around the figures of what you are used to, I would have thought.

Posted by: @wally

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@jamespa Regrettably I have no idea. However I am due a call from Aira and will pose that question. As a matter of interest, what would you expect the figure to be?

My consumption figures, for a house in the South East that has a measured loss of 7kW at -2, are here  My SCOP is roughly 4, but of course in the coldest months COP is lower.  Im running pure WC at a FT of 42@-2.  I have no buffer tank/LLH, rads are directly connected to heat pump.  The numbers given are for the ASHP only.  A typical house consumes 300-400W on average excluding EV/Heat pump, ie about 8kWh/day.

@wally, welcome to the forums.

I’ll probably repeat a few things others have said, but it’s a common challenge for many switching from oil to an air source heat pump, especially in the first winter… We were the same. The jump in energy costs can feel alarming, but there are a few factors and strategies that might help you better manage your system and understand what’s going on.

Firstly, ASHPs work most efficiently when running at lower flow temperatures over longer periods, rather than short bursts of high-temperature heating. Your thermostat setting at 19C is reasonable, but the uneven temperatures you describe (warmer upstairs and much cooler downstairs) suggest that your system’s zoning or heat distribution isn’t optimised. Since your Aira system treats the whole house as one zone, it can’t tailor heating to different rooms, which often leads to some areas overheating while others stay cold. 

Regarding your tariff, time-of-use plans can offer savings if you can shift your heat pump’s operation to off-peak times, but without a battery or thermal store to shift heating load, the benefits are limited. Heat pumps typically run most when it’s coldest, which often coincides with peak electricity rates. Using your tariff mainly for appliances like washing machines and dishwashers is a smart way to get some benefit, but for heating, it’s trickier without additional storage or control strategies.

It’s also worth noting that the biggest savings from ASHPs often come over the full year, including spring and summer when heating demand is lower and the heat pump can run more efficiently. The first winter can feel expensive because the system is working hard to heat your home, and the transition from oil means you’re now paying for electricity rather than oil, which can feel more costly upfront. January and February can be scary, but bills drop drastically in shoulder months.

Since Aira and Home Energy Scotland are engaged with you, keep working with them to review your system settings and controls. Sometimes small tweaks to pump speeds, flow temperatures or control logic can make a big difference. Also, monitoring your daily energy use and heat pump run times can help identify patterns and opportunities for improvement.

Lastly, while the initial bills can be daunting, many users find that with time, system tuning and behavioural adjustments, their energy costs settle closer to or below their previous heating bills. The key is patience and ongoing optimisation.

Hope this helps, and welcome to the forum… there’s a lot of collective experience here to support you through this transition.

@editor 
Mars,

@wally Hope your issues are sorted out soon.

We have an Aira heat pump and hope my thoughts can help with some of your issues. For context, we have a 6 kW heat pump for a 200-square-metre house in the South East; it is a relatively new build (completed within the last 15 years). This December has been very cold here, and we consumed about 460 kWh, compared to about 380 kWh in November. We do have solar panels and batteries and are on Octopus Go, averaging 12 pence per kWh in November and 14 pence in December. Our heat pump was installed in January 2025, and in February we used about 600 kWh in what was a very cold month, January 2026 should be much higher than that given how cold it has been.