Daikin Altherma 3 8kW not working as needed

Aksel · 2023-12-12T17:13:11Z

I have had this pump for 9 months now. Before a week ago, all the radiators around my 160 sq meter 2 story house were consistently warm and we were happy with even much colder weather than now. Now instead I see that the pump works for like multiple hours, then sits idly for over an hour while all radiators in my living room go completely cold and we suffer shifting room temperatures. Is there a way I can make the pump try and keep radiators hot all the time? I have quite a badly insulated house.

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Air Source Heat Pumps (ASHPs)

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Marzipan71

(@marzipan71)

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Joined: 3 years ago

Posts: 102

22/02/2024 8:41 am

Hi @toodles sounds very much like our situation with our Daikin - we have three people in the house, two of us working from home. Our daily 'background' (non-heating, non-DHW) averages 12 kWh in the winter - from three years of data I've determined that breaks down to 5 kWh for normal variable activity, 4 kWh for non-ASHP background (e.g., average consumption when we are holiday), and 3 kWh for the ASHP 'background' - what it uses just being switched on and doing nothing useful; on top of that our DHW (two cycles per day, one 5.30am, one 1pm) averages 5 kWh. Its sounds as you say like we are in the same ballpark - albeit our absolute heating demand is higher due to sq m - we are (12 + 5 + 28.5) to your (10 + 4 + 12) for (background + DHW + heating), if I'm reading correctly. Do you use setback or is the space heating 'on' 24x7?

I think I saw an article by Protons for Breakfast where he looked at a histogram of his kWh consumption - I followed his approach and to your point it was comforting to see that yes those cold days of high consumption really are outliers - this is how my data looked last winter (total grid consumption for winter heating season 22-23):

If I subtract 17kWh from the data I more or less get my space heating kWh consumption - i.e., same distribution.

We also have 6.1 kWp of solar (averaging around 11 kWh p/d in this heating season, of which on average we use 9 kWh p/d), no batteries, UFH + rads, 30cm loft insulation, double glazing for comparison.

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Toodles

(@toodles)

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Joined: 3 years ago

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22/02/2024 9:01 am

@marzipan71 Hello Marzipan, I did experiment with setback but it didn’t appear to reduce consumption according to the readings. I suppose any resting time had to be compensated for when returning to ‘normal’ settings again. Both being retired, we are here most of the time so 22.5 degrees C. 24/7 suits us well. Homely is very good at holding the temperature constant for most of the time - I have found that there is a rise of 0.6 to 0.75 in the early evening and that may have been Homely making best use of OE’s Cosy tariff but I have just swapped back to Agile so will see. More later no doubt! Regards, Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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