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Help needed with Grant Aerona 3 issues

 
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Air Source Heat Pumps (ASHPs)
Last Post by JamesPa 12 minutes ago
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 3768
29/12/2025 1:28 pm  

Posted by: @fleurcules
↑

It was sitting at 35 for a bit, now up to 36. Although oddly the rads have just gone from feeling about as warm as they ever do to feeling noticeably colder.

OK well so far as I can see there are now only three possibilities

 

1. The heat pump is unable to get up to the set temperature because of a fault

2. The heat pump is unable to get up to the set temperature because too much energy is being dissipated even though there is no fault.

3.  The heat is unable to get up to the set temperature because something else is stopping it even though there is no fault and its not dissipating a load of energy.  However I can see what condition would caused this.

In case (2) then something (eg the house) would be getting pretty warm with perhaps 14kW flowing into it.  In case (3) you would at least expect it to cycle.

You could check return temp and flow rate in the UI to calculate how much heat the heat pump is generating, and electrical power consumption to check how that corresponds.  This would unequivocally differentiate the cases above.

I would say 95% probability there is a fault with the unit itself.  I would do those final checks (when its running obviously), summarise and approach your installer/Grant to fix.  Im surprised the A1 error isnt constant unless there is in fact another internal fault as yet unrevealed. 

 


4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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 fleurcules
(@fleurcules)
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Joined: 1 day ago
Posts: 8
Topic starter 29/12/2025 2:06 pm  

Ok think I'm done tinkering, have gone back to WC mode. Under fixed temp settings the highest it got to was 36, then dropped back to 35/34.

@jamespa thanks for all of your help so far! 

Edit: just seen your most recent reply. Energy consumption is pretty much steady at around 2kW whenever it's on (only higher if e.g. the kettle is on, occasionally drops lower).


This post was modified 58 minutes ago by fleurcules
This post was modified 56 minutes ago by fleurcules

   
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 3768
29/12/2025 2:55 pm  

Posted by: @fleurcules
↑

Ok think I'm done tinkering, have gone back to WC mode. Under fixed temp settings the highest it got to was 36, then dropped back to 35/34.

@jamespa thanks for all of your help so far! 

Edit: just seen your most recent reply. Energy consumption is pretty much steady at around 2kW whenever it's on (only higher if e.g. the kettle is on, occasionally drops lower).

Noted.  Its a pity you didnt capture the flow rate and return temp when it was in fixed FT mode, but you could capture it now or just go for the 95% case that there is a fault (unless of course Im missing something!) and get Grant in.

Assuming you do do that don't let the engineer tell you its working until he/she has demonstrated operation at 55C or thereabouts, ie sufficient to heat DHW!  Good luck!

 


This post was modified 10 minutes ago by JamesPa
This post was modified 9 minutes ago by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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