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What Air-to-Air (Air conditioning) system do you have and how efficient is it on heating and cooling

 
Air-to-Air Heat Pumps & Air Conditioning
Last Post by Rob of York 3 weeks ago
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 Rob of York
(@rob-of-york)
Trusted Member Member
Joined: 3 weeks ago
Posts: 64
Topic starter 25/08/2026 2:14 pm   [#3144]

We have two single-split Daikin Comfora A2A systems these are a 2.5 kW unit upstairs in the main bedroom and 3.5 kW unit downstairs in the lounge. The house is a 4-bed 1970's detached, about 150 sqm ,with a lot of retrofit insulation. 

The A2A units have been in place for just over 1 year now. Over the heating season, we used the downstairs unit to add heat on cheap rate overnight electricity and both units on the "indoor quiet" setting to add some extra heat during the day, mainly running our solar PV output. This was enough on its own on many autumn and spring days, and was supplemented by our gas boiler in the depths of winter, when we only used the A2A overnight. 

Overall efficiency on heating was 5800 kWh of heat delivered for 1110 kWh of electricity consumed for an efficiency of 5.2.

On cooling over the 5 heat waves so far in 2026, we got 600 kWh of cooling (heat ejected from the house) for 64 kWh of electricity used for a efficiency of 9.3

On heating our average cost per kWh of heat delivered was under 2p, so far cheaper than gas. (Note this includes both cheap rate overnight electricity consumed from the grid and lost solar PV export at 12p per unit).

Overall, we are very pleased with our A2A system. The two units do a very good job of cooling both upstairs and downstairs, with an extra fan employed occasionally to push cool air around to other rooms. It is very nice to have the house at 24C when it is 34C for hours on end outside! The excellent efficiency on heating was an added bonus, but has turned out to be when we make the most use of the system.

Rob



   
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Mars
 Mars
(@editor)
Illustrious Member Admin
Joined: 6 years ago
Posts: 4853
25/08/2026 3:22 pm  

@rob-of-york welcome to the forums. 

Solid numbers. A seasonal heating figure of 5.2 is impressive enough, but what I like is that you’re not pretending the system exists in isolation. You’re using cheap rate electricity, solar when it’s there and the gas boiler when conditions make that sensible. 

The cooling side is interesting too. 64kWh of electricity across five heatwaves to keep the house around 24C when it’s 34 outside sounds like a very small price to pay for the comfort.

What I’d be interested to know is how evenly those two units heat the house in winter. With one upstairs and one downstairs do the more remote rooms still stay reasonably comfortable, or are you mainly heating the core of the house and letting the boiler pick up the rest?

Also, how are you measuring the 5,800kWh of heat delivered? Is that coming from the Daikin app?

Really useful first post.


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 Rob of York
(@rob-of-york)
Trusted Member Member
Joined: 3 weeks ago
Posts: 64
Topic starter 25/08/2026 3:49 pm  

@Mars Good questions!

The downstairs unit did the majority of the heating in winter, as this was overnight taking advantage of cheap rate electricity, and we didn't want to run the upstairs unit in our bedroom while sleeping. So 4800 kWh from the downstairs unit and 1000 kWh from the upstairs one. The heat dispersed reasonably well with the downstairs doors all open and also the upstairs ones to rooms not in use.

The situation was reversed in summer, with the downstairs unit contributing 220 kWh of cooling and the upstairs one 380 kWh. They were typically both run at the same time during the day, but of course heat rises, so the upstairs unit had more work to do.

In autumn and spring, there was enough heat transfer around the house to even out temperatures well enough to not need to use the gas central heating at all. However, on cold days in winter, this wasn't the case and we needed to switch to using gas central heating during the day. The drop in room temperatures was a lot better though than when we had no supplementary heating overnight and the boiler switched off. 

Measures of heat delivered and electricity used are from the Daikin app, so subject to the vagaries that may entail.

Rob



   
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