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After using my 11kw TRIAQUA air source heat pump of and on for 10 years I found it a useless match to our daily living routines. We live in the Alps at 780 metres and had temperatures from as low as minus 24 Celsius to as high as +10 on cold Winter nights generally December and January are the coldest months. In order to get any warmth and comfort in our home in Winter we had to leave the pump running 24 hours 7 days a week which goes against all our inclinations to save energy. In our first year of operation we had a bill of 2600 Euros to heat our house at temperatures of somewhat less than 20 degrees. Our preference is to sleep in a cold room and to have our sitting room at around 24 degrees when it is minus 10 or below outside. In the morning for breakfast after we rise we are looking for 20-24 degrees instantly in the main sitting room and adjoining kitchen. We found none of the above was achievable at a sustainable cost using our heat pump which is supposed to have a COP of 2.8 from memory. At minus 2 our heat pump simply switches to the back- up internal electric heating element which runs at about  3 kw power usage. For us that works more efficiently than the pure air sourced power unit. But neither can ever achieve 24 Celsius in our main living areas when the outside temperatures are anywhere in the minus range. All in all if we had SOLAR generating above 5kw of power we would be better off just having an electric powered boiler and forgetting about using the heat pump full stop. We did not want to install Solar or wind power because Solar requires sun and that does not shine at night when we need most power so we then need storage batteries and the average windspeed in our valley was then less than 2 metres /sec. We solved our comfort needs by installing a 23 kw Swedish wood burner  16kw to the boiler and 7 kw to our main living room and connecting this into the heat pump radiator system. Our wood cost is 1000 Euros a year with mostly 24 degrees in the living area and background heat in the bedrooms for sleeping. Now we switch the heat pump on for one day a year for testing only.

DOES ANYONE HAVE SIMILAR EXPERIENCES WITH AIR SOURCE HEATPUMPS?              

You are absolutely correct that a heat pump will not give you instant heat. In the same way that you cannot expect to get ice cubes from a freezer until it’s been running for some hours !

Sounds to me like the design of your heating system hasn’t taken into account your heating requirements. If you want, but cannot achieve, 24 degrees in your living space you need larger emitters (eg radiators). If you want cold bedrooms they need to have smaller emitters rather than turn them off. 
 

Updated on 02/05/25 by Ben_OVO

​@JOLLYROGER 

I’m not surprised you are having problems with the ASHP. They don’t perform very well when below zero as the COP is very much reduced and they ice up frequently so they spend a significant amount of time on defrost cycles when they don’t produce any heat. As you say the ASHP switches to a 3kW heater when below -2C which and 3kW not going to be adequate for a large inside to outside temperature differential. What you are describing is quite normal and the best solution in your circumstances is your wood burner. The ASHP would work better in the autumn and spring but it will still need help from the wood burner on colder days.

 

I have a heat pump as well but supplement it with gas central heating and a wood burner on the coldest days. It’s a combination that works well but the average daily temperature here is seldom below zero where I am in the UK although it can drop to -5C at night.

 

Peter

 

​@Peter E I disagree. This may be usual for a ten year old system that was badly designed ! The lowest temperature I’ve known was -7 deg C and even then the backup heater was not used.

We have high humidity in Britain so our heat pumps do spend time doing frequent defrosts, more than ​@JOLLYROGER will experience in the much drier mountain air in the Alps.
I suspect there’s a few things not right with their system or the way it was being operated for it to perform so poorly.

Hey ​@JOLLYROGER,

 

Great question and welcome to the community! 

 

Have you been able to review the advice from ​@juliamc and ​@Peter E, and share any photos of your setup that you may have.  Additional details, such as emitter sizes (radiators, etc.), as Julia mentioned, would also be beneficial.

 

Remember that testing something for only a day will provide very limited results. To gain a more accurate overview, you should consider extending the testing period and diligently documenting the outcomes. The results may surprise you.

 

thanks all very helpful 

I’m glad you found that helpful ​@JOLLYROGER 🙂

We have a number of green tech enthusiasts & heat pump owners on the forum so pop back with any questions you have!

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