Renewable Heating Hub Heat Pump Forums

Search with Wattson
Forums
Renewable Heating
Air Source Heat Pum...
System pressure and...
 
Notifications
Clear all

Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!

System pressure and COP

 
Air Source Heat Pumps (ASHPs)
Last Post by ChandyKris 9 months ago
4 Posts
2 Users
1 Reactions
1,456 Views
RSS
 ChandyKris
(@chandykris)
Reputable Member Member
Joined: 2 years ago
Posts: 207
Topic starter 26/12/2025 4:42 pm   [#2687]

A couple of days ago, I noticed that the pressure had dropped to nearly 1 bar. The installers had mentioned that the ideal pressure is around 1.5 bar. So, I re-pressurised to the appropriate level, and since then the COP has gone up slightly with respect to days comparable in temperature. For example, yesterday was very cold, around 2 degrees Celsius, but we still managed to reach a COP of 4 for the day, including hot water. On a similar day earlier in the month, we probably reached just around 3.5 COP. Does the system pressure matter for COP, or is this just a correlation and not causation?

 


16 * 435 watts PV
13 kWh Growatt battery
1 EV - Mercedes EQB
6 kW Aira Heat Pump
Bosch Induction Hob
Pod Point Solo 3 charger


   
Quote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 5446
26/12/2025 6:58 pm  

Posted by: @chandykris
↑

Does the system pressure matter for COP, or is this just a correlation and not causation?

Provided it's sufficient I can't think of any reason in physics why system pressure would affect cop


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.


   
ReplyQuote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 5446
26/12/2025 6:58 pm  

Posted by: @chandykris
↑

Does the system pressure matter for COP, or is this just a correlation and not causation?

Provided it's sufficient I can't think of any reason in physics why system pressure would affect cop


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.


   
👍
1
ReplyQuote
 ChandyKris
(@chandykris)
Reputable Member Member
Joined: 2 years ago
Posts: 207
Topic starter 26/12/2025 7:01 pm  

Thanks @jamespa


16 * 435 watts PV
13 kWh Growatt battery
1 EV - Mercedes EQB
6 kW Aira Heat Pump
Bosch Induction Hob
Pod Point Solo 3 charger


   
ReplyQuote
Forum Jump:
  Previous Topic
Next Topic  
Share:

SPONSORS

Join Us!

Installer Finder

Degrees of Separation

Latest Posts

SPONSORS

Members Online

Click to access the login or register cheese
Protected By
Shield Security PRO