Renewable Heating Hub Heat Pump Forums

Search with Wattson
Forums
Renewable Heating
Air Source Heat Pum...
Has anyone seen thi...
 
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!

Has anyone seen this problem before? Huge anticycling times

 
Page 2 / 2
Air Source Heat Pumps (ASHPs)
Last Post by JamesPa 3 months ago
16 Posts
6 Users
3 Reactions
7,179 Views
RSS
 jamesh
(@jamesh)
New Member Member
Joined: 12 months ago
Posts: 6
20/11/2025 2:07 pm  

For the information of others. Vaillent came today, checked everything and decided to change the electronic circuit board in the machine. Hopefully this is a final fix and it's not all good - as winter is just about to hit properly. 



   
🙏
1
ReplyQuote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 4 years ago
Posts: 5607
07/08/2026 4:00 pm  

Posted by: @cg360
↑

The faults are:

F703 - low pressure

F585 - sensor fault capac. outlet temp

F520 - sensor fault building circuit flow temp

F519 - sensor fault building circuit return temp

F73 - building circuit water pressure

The fault goes away if I turn off the house mains and switch it back on. But how long it will work for is another question. I've reset the mains seven times today just to heat the hot water.

Im now getting the exact same fault list after 2 years of trouble free operation.  I am faintly suspecting overheating (the heat pump is on a south facing wall and the top gets too hot to touch; the main circuit board is just underneath!) and/or marginal circuit board.  I have heard that its a 'known problem'.  Is there any more intelligence anyone can share before I call Vaillant (I have also put a sunshade over it to test the 'overheating' theory)

 


This post was modified 3 months ago 4 times 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.


   
ReplyQuote
 cg360
(@cg360)
New Member Member
Joined: 3 years ago
Posts: 4
Topic starter 07/08/2026 11:23 pm  

Mine was replaced as they couldn’t fix and couldn’t identify the fault. But mine is on a north facing wall and gets very little sun, fault occurred all year so i doubt overheating was the issue in my case. Good luck!



   
ReplyQuote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 4 years ago
Posts: 5607
08/08/2026 7:30 am  

Posted by: @cg360
↑

Mine was replaced as they couldn’t fix and couldn’t identify the fault. But mine is on a north facing wall and gets very little sun, fault occurred all year so i doubt overheating was the issue in my case. Good luck!

Oh dear.  Glad it was replaced.  I have been mighty impressed up until now this is shaking me a bit.

 


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
Page 2 / 2
Forum Jump:
  Previous Topic
Next Topic  
Related Topics
Topic Tags:  heatpump (2) , anticycle (1) , problem (2) ,
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