High electricity use – 17kW Grant Aerona 3

JgtukPD · 2025-02-13T14:40:13Z

Hi all. Had a 17kw Grant Aerona 3 ASHP and Solar Panels fitted May '24 so it didn't get much use until around October '24. Radiators were all replaced/upgraded to K2 and K3 types. Bills were low-ish in the summer as obviously no heating required, only hot water once per day. Since the temperatures dropped the heating has been on constantly, two circuits, upstairs and downstairs, 2 stats set to 18 degrees. House temp is mostly ok but our electricity use has gone through the roof. We're using 1800kWh per month for december, January and probably February, one day exeeded 110kWh in December! We don't have any other form of energy so I realise that these figures include our electric hob and oven (used once daily for 1hr), microwave (used 3/4 times daily for short periods), washer and dryer 9 Used twice per week) and all other electrical items. Our house is an old, well insulated house, two occupants, both in all day working from home, running two computers 9 hours per day. The house is a detached 5 bed stone with slate roof. The installers aren't interested, they said everything is alright and it's working properly... Does anyone exist who will come and assess/set up the system properly as I suspect it might improve if 'tuned'. I've read heaps about changing settings but it's too confusing for me to entertain... We're in N. Wales nr Ruthin. Thanks.

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Air Source Heat Pumps (ASHPs)

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15/02/2025 1:05 pm

Posted by: @jgtukpd

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I spoke with my electrician just now who told me that the original supply (when hp was installed) was single phase but was upgraded to 3phase just after.

The upgrade to 3-phase was most likely initiated by your DNO.

It's possible that they did stipulate the need for this as a result of communications with your ASHP installer...
... but that he didn't appreciate the significance, and thus proceeded with the work before the supply was upgraded to 3-phase.

That's why we need the correspondence which SPEN sent to your installer.
It should've been included in the documents given to you on completion of the HP work, but there's no problem asking for a copy anyway.

I don't believe Grant offer 3-phase heat pumps.
So if that's what your installer favours, then it's possible he was wary of switching to a different model outside of his comfort-zone.

Save energy... recycle electrons!

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