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Minimum and Zero Disrupt Heat Pump Installations

 
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Air Source Heat Pumps (ASHPs)
Last Post by Batpred 18 hours ago
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 L8Again
(@l8again)
Eminent Member Member
Joined: 4 months ago
Posts: 23
Topic starter 13/05/2026 8:30 am  

@batpred As my installation survey was carried out under the HG assured warranty scheme, my installer didn’t get much say as to the size of the heat pump. What I can say is that with no radiator changes, the HG survey was looking at a 5kW Valliant with a SCOP of 3.7. I elected to go for some radiator changes based on running my boiler at 50C for past 2 years. These radiator changes increased the minimum SCOP to 4 based on a 7kW Valliant. My predicted heat loss is 5.9kW at -3C.

A month or so on my system has stabilised on a 0.2 heat curve with an internal temp of 19.7C. All radiators fully open in Weather Compensation mode manual with room temp mod ACTIVE. Yes, I do get HP cycling: 338 cycles with just over 200 hours of operation. Having the heat pump cutout temperature set at 14C seems to be working well. So far in May, the heat pump has consumed 50kWh of electricity to cover heating; hot water and cylinder disinfection. I don’t have heat pump monitoring but looking at a similar sized heat pump (SCOP4.5) in my location which does have live monitoring, my recorded performance is closely matching it - particularly in respect of flow temps; daily usage and costs.



   
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Batpred
 Batpred
(@batpred)
Prominent Member Member
Joined: 1 year ago
Posts: 872
13/05/2026 12:15 pm  

Posted by: @l8again
↑

@batpred As my installation survey was carried out under the HG assured warranty scheme, my installer didn’t get much say as to the size of the heat pump. What I can say is that with no radiator changes, the HG survey was looking at a 5kW Valliant with a SCOP of 3.7. I elected to go for some radiator changes based on running my boiler at 50C for past 2 years. These radiator changes increased the minimum SCOP to 4 based on a 7kW Valliant. My predicted heat loss is 5.9kW at -3C.

Thanks, that's very useful to know. I believe us using -2C is due to being in the SE. 

We are still waiting for HG to come back to us on the specifics, hence we are self evaluating the pump modulation bands. 

Vaillant is our preference, but the pricing is hitting the tight budgetary constraint! And we will not postpone the rad upgrades.. 

 


8kW Solis S6-EH1P8K-L-PLUS hybrid inverter; G99: 8kw export; 16kWh Seplos Fogstar battery; Ohme Home Pro EV charger; 100Amp head, HA lab on mini PC


   
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