Grant Aerona3 R32 HPIDI17 performance in low temperatures

davidm06 · 2025-01-19T13:24:40Z

We have a Grant Aerona3 R32 17kW installed in 2022. I have some concerns as our costs are very high and out of line with our experience with a Daikin Altherma installation that we had in Wales for 13 years. It seems to related to a defrost mode as when the outside temperatures fall to below zero, the pump starts working like mad continually. We have recently been away and I had switched the water heating off and kept temperature in the house at 10C. On a warm evening our daily electricity usage was 0.9kWh so all good. However on cold nights, it jumped significantly to up to 39kWh. That is not sustainable financially and to me is not right. I fully understand there has to be a defrost mode but this seems a bit ridiculous. Does anyone have any advice about what I should be asking of our suppliers?

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Air Source Heat Pumps (ASHPs)

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davidm06

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Topic starter 25/01/2025 11:41 pm

That was in the inside room temperature

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Uk_pete_2000

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26/01/2025 12:11 am

@davidm06 forgive me but you must be freezing at 10c inside. Most people have it set to around 20•c

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davidm06

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Topic starter 26/01/2025 9:12 am

We were away for three weeks so put the temperature down and hot water off. Despite this, our daily costs were high due solely to the defrosting cycle

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Uk_pete_2000

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26/01/2025 9:39 am

Okay understand now. Even though we get defrosting cycles we could reduce them by running the HP at a much lower flow temp. At present we try to run between 25 to 27°c which keeps the house around 19.

We also try to only run during the day.

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