Renewable Heating Hub Heat Pump Forums

Search with Wattson
Forums
Renewable Heating
Air Source Heat Pum...
Compressor attempts...
 
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!

Compressor attempts start but fails - Nibe Fighter 2005 8kW

 
Page 1 / 2
Air Source Heat Pumps (ASHPs)
Last Post by skyefarmer 6 months ago
15 Posts
5 Users
9 Reactions
2,481 Views
RSS
 skyefarmer
(@skyefarmer)
Active Member Member
Joined: 1 year ago
Posts: 8
Topic starter 05/07/2025 11:35 am   [#2376]

Hoping someone may have seen this problem before. I have a Nibe Fighter 2005 8kw single phase heat pump which heats a swimming pool. From yesterday it is failing with the following behaviour. Starting from a full power off reset, the system waits 20 mins before attempting to start the compressor; after 20 mins I hear the compressor motor startup noise for about half a second, after which it stops; the fan continues to rotate; the system stays on, but evaporator temp, hotgas temp, etc are not right; after about 5 mins the compressor motor attempts to start again with a short pulse of noise, then stops; after the second attempt the system alarms and stops with "fan alarm" (but don't focus on "fan" because I have learnt that the alarm descriptions are pretty random).

The system had been working fine all winter (for background heating and frost protection, not pool heating) and has been heating pool fine for a few weeks this summer.

I'm on the Isle of Skye, with nearest heat pump engineers 2 hrs away, so I have looked after this heat pump myself for years: so far, 3 replaced temperature sensors and a new soft start unit (2yrs ago).

Unluckily for me this latest fault happened at 5.30 on a Friday, and the only guy who has ever helped me by phone finishes work at 5!

Any insights or advice would be gratefully received. It's been pouring with rain here for a few days so I haven't opened the heat pump lid to start poking around, see if anything looks amiss, etc.

The system is pretty old, maybe 15-18yrs, and we've had it from new.

Thanks



   
Quote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 5198
05/07/2025 12:12 pm  

I had a very similar problem with my valiant and it turned out to be a blocked filter.  Unbeknown to me I have a very fine filter in addition to the mag filter.  Heat pump engineer told me this accounts for 90 percent of call outs so definitely worth checking.


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
 skyefarmer
(@skyefarmer)
Active Member Member
Joined: 1 year ago
Posts: 8
Topic starter 05/07/2025 12:38 pm  

@jamespa Thank you! As soon as it stops raining I will check that out. Looking at manual now.



   
ReplyQuote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 5198
05/07/2025 2:24 pm  

It might not be in the manual, mine was a rather innocuous third party 40mmx80mm brass fitting between the heat pump isolation valve and the heat pump itself, on the return.

It may of course be something completely different.  Any fault codes?

 

 


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
Mars
 Mars
(@editor)
Illustrious Member Admin
Joined: 5 years ago
Posts: 4763
05/07/2025 2:39 pm  

Posted by: @jamespa
↑

I had a very similar problem with my valiant and it turned out to be a blocked filter.  Unbeknown to me I have a very fine filter in addition to the mag filter.  Heat pump engineer told me this accounts for 90 percent of call outs so definitely worth checking.

That's a very good suggestion. I'd forgotten that we had a similar issue a couple of years ago, but ours was accompanied with an error on the screen that I translated into a flow error. Given the age of @skyefarmer's system, I'm not sure the control panel throws up error codes. @skyefarmer do you have any errors?

In closing, that is probably the best name for a heat pump to date. "What heat pump do you have?" The "Fighter". Terrific name!

 


New to heat pumps? Take the Heat Pump Fundamentals course and use INTRO50 at checkout for 50% off.
Rewritten and updated for 2027
📘 From Zero to Heat Pump Hero
🛠️ Bodge Buster
🎧 Prefer to listen? Heat Pumps Explained


   
ReplyQuote
 skyefarmer
(@skyefarmer)
Active Member Member
Joined: 1 year ago
Posts: 8
Topic starter 05/07/2025 2:43 pm  

 

Nibe Fighter 2005 Capacitor

Update: It finally stopped raining and I opened up the heat pump. The attached picture tells the story. Quite surprised that can happen!

So I'm currently searching for an appropriate replacement capacitor for the Ducati energia 16.33.5660

I usually use RS Components, but not looking good. Does anyone know what the modern equivalent is? Thanks. Will let you know if I find it.

Update 2: I've ordered a Ducati Energia 4.16.33.56.60 from TME Electronic Components. Fingers crossed for the new one fitting and me being able to salvage the wiring.



   
👍
1
ReplyQuote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 5198
05/07/2025 3:59 pm  

@skyefarmer pleased you found it!


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
Mars
 Mars
(@editor)
Illustrious Member Admin
Joined: 5 years ago
Posts: 4763
06/07/2025 7:42 am  

@skyefarmer great you located the source of the issue and that you have the skills to replace the capacitor. Fingers crossed!


New to heat pumps? Take the Heat Pump Fundamentals course and use INTRO50 at checkout for 50% off.
Rewritten and updated for 2027
📘 From Zero to Heat Pump Hero
🛠️ Bodge Buster
🎧 Prefer to listen? Heat Pumps Explained


   
ReplyQuote
 Scalextrix
(@scalextrix)
Estimable Member Member
Joined: 2 years ago
Posts: 127
06/07/2025 2:50 pm  

Posted by: @skyefarmer
↑

The attached picture tells the story.

"To tell you the truth, I don't know if HAL is homicidal, suicidal, neurotic, psychotic, or just plain broken."

I think we know which category yours falls into @skyefarmer 

Good luck getting it fixed.



   
ReplyQuote
 skyefarmer
(@skyefarmer)
Active Member Member
Joined: 1 year ago
Posts: 8
Topic starter 19/07/2025 8:20 am  

Update: All fixed. Replacement Ducati capacitor is in. The only delay was getting hold of some stranded copper wire of suitable diameter to handle the start up current (approx 16A).



   
👍
2
ReplyQuote
Mars
 Mars
(@editor)
Illustrious Member Admin
Joined: 5 years ago
Posts: 4763
19/07/2025 9:31 am  

@skyefarmer amazing. Well done!


New to heat pumps? Take the Heat Pump Fundamentals course and use INTRO50 at checkout for 50% off.
Rewritten and updated for 2027
📘 From Zero to Heat Pump Hero
🛠️ Bodge Buster
🎧 Prefer to listen? Heat Pumps Explained


   
ReplyQuote
 Ian@21stCent
(@ian21stcent)
New Member Member
Joined: 6 months ago
Posts: 1
29/01/2026 8:49 pm  

@skyefarmer I see you have had a good bit to do with the same GSHP I have, just had my Fighter 1140 make a loud noise and so dirty it make house light flicker with electical noise and after a shutdown and restart it will not start the compressor, the Emerson ESC-255 has a Fault Mode LED error. Not sure if I should swap soft start...I can't find any info on what triggers the fault mode on the ESC-255. 



   
🤔
1
ReplyQuote
Page 1 / 2
Forum Jump:
  Previous Topic
Next Topic  
Share:

SPONSORS

Join Us!

Installer Finder

Degrees of Separation

Latest Posts

SPONSORS

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