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Help…my NIBE heat pump has faulted again!

 
Air Source Heat Pumps (ASHPs)
Last Post by JamesPa 3 weeks ago
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 Fiona
(@fiona)
Active Member Member
Joined: 1 year ago
Posts: 7
Topic starter 30/11/2025 10:43 am  

Hi. I won’t go into the background of my heat pump installation and everything that was wrong with it. The installers are no longer in business. A report suggests our heat pump is not big enough for the house. Every time it gets below 2 degrees it faults and we get the following alarm message. Any idea what this is and how we might fix it? It is something about the short compressor…. Thanks!

IMG 9509

 


This topic was modified 3 weeks ago by Mars

   
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 3734
30/11/2025 11:20 am  

There isnt a short compressor, its that the operating time of the compressor is too short.  According to google it may be due to low refrigerant level or component malfunction (the other reason for compressor operating time too short is short cycling - but at 2C thats unlikley).

If Google is correct you will need a Nibe repair man


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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 Fiona
(@fiona)
Active Member Member
Joined: 1 year ago
Posts: 7
Topic starter 30/11/2025 11:28 am  

@jamespa thank you. At this stage (3rd winter with it cutting out when cold) I’m on the verge of seeing if it’s possible to replace the pump and putting a gas boiler back in. It’s costing so much money getting people to try and fix it and nothing ever seems to actually make it work properly. So disappointed 



   
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 JamesPa
(@jamespa)
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Joined: 3 years ago
Posts: 3734
30/11/2025 11:34 am  

Posted by: @fiona
↑

@jamespa thank you. At this stage (3rd winter with it cutting out when cold) I’m on the verge of seeing if it’s possible to replace the pump and putting a gas boiler back in. It’s costing so much money getting people to try and fix it and nothing ever seems to actually make it work properly. So disappointed 

Have you actually had a Nibe engineer in or just an installer.  You probably shouldnt be paying anything if Google is right, it should be a warranty issue, Nibe are a premium brand so its disappointing if they wont engage.  They say they will here https://www.nibe.eu/en-gb/about-nibe/contact-us

Precisely which model is this?

It could alternatively be to do with the downstream system (your radiators/UFH).  What do you have, do you have zone valves, TRVs or room thermostats, if so how are those set?  Does this ONLY happen when its 2C or below

image

This post was modified 3 weeks ago 5 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.


   
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Mars
 Mars
(@editor)
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Joined: 5 years ago
Posts: 3849
30/11/2025 8:46 pm  

@Fiona, James is right. The unit should still be under warranty and I'd strongly recommend contacting NIBE for them to come and check it out. If you're battling, I can contact NIBE on your behalf.


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 Fiona
(@fiona)
Active Member Member
Joined: 1 year ago
Posts: 7
Topic starter 01/12/2025 8:55 am  

Thanks both. We’re going to contact the people who last came to look at it today and take it from there. Every time we’ve phoned NIBE in the past they just point us to accredited installers who this guy is. I think he does know how to get in touch with them though so hopefully he can sort it. This is the same alarm we get every year though when it gets cold and we’d hoped whatever the guy did last year would have fixed it so hopefully we can get some resolution this time. 



   
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 3734
01/12/2025 9:25 am  

Posted by: @fiona
↑

Thanks both. We’re going to contact the people who last came to look at it today and take it from there. Every time we’ve phoned NIBE in the past they just point us to accredited installers who this guy is. I think he does know how to get in touch with them though so hopefully he can sort it. This is the same alarm we get every year though when it gets cold and we’d hoped whatever the guy did last year would have fixed it so hopefully we can get some resolution this time. 

If it happens only when it gets cold then it maybe that the heat pump tries to increase flow rate at lower outside temps/higher flow temps, and fails due to too much resistance.  This could be as simple as a filter blocking up which is unfortunately a maintenance item, probably roughly annually.  Why don't you find out what he does.

 


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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