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[Sticky] Struggling to Find a Top Heat Pump Installer? We Can Connect You With the Best Installers in the UK

 
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Air Source Heat Pumps (ASHPs)
Last Post by JamesPa 5 days ago
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JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 4313
18/02/2026 8:42 am  

Posted by: @editor
↑

Posted by: @jamespa
↑

I had exactly the same experience, 2x+ oversizing (16kW 'surveyed' vs 7kW measured).

I just don’t understand how this is still happening and this problem is not going away. Our local heating engineer (who will be working on our system soon) stopped by for a quick chat and coffee yesterday.

He’s just won a new ground source heat pump project on a large new build nearing completion, 450sqm with a heat loss around 13. The homeowner, he says, is disengaged and not asking any questions, and the proposal they nearly accepted was for a cascade system with 2 x 12kW units. 

In fairness my experience was 2 years ago.  However the example you quote and that of @simonb seems to confirm it is still happening.  

The change to the calculation methodology which was mandatory from mid last year should have dealt with the ACH problem at least to an extent, assuming of course that installers have updated their methodologies.  However it wouldn't do anything for the problem of ignoring fabric upgrades (GIGO!) and possibly not for double counting.  As you say there still appear to be some ludicrous numbers out there, so ludicrous that a bit of elementary sense checking would easily spot them.

 


This post was modified 5 days 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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