CH pump: Grundfos UPS3 15-50/66

[Diwali]

My CH pump shows the LED alarm for a ‘blockage’ however, the impeller turns freely (with a screwdriver) when the pump is turned off but, when I turn it on, the impeller does not spin. This indicates to me that the pump presumably has an electrical fault. Has anyone had experience in fixing this type of issue or am I looking at replacing the (expensive!) pump? The pump is 2 tears old.
Thanks

 

[Johntheo5]

You have tried it in different operating modes??
You should be able to remove the 4 stud bolts and remove the head, clean all parts that are accessible and reassemble.

 

[Diwali]

Thanks for the response.
I’m not able to change the operating mode due, I think, to the alarm signal staying on.
Tomorrow I will dismantle the pump and give it a clean (and report back).

 

[CBW]

Have you tried turning it with the power on?

 

[Diwali]

A risky move but yes I did try - but no go.

 

[CBW]

I’m not sure why it’s risky, but if it’s not moving when connected it might be goosed electrically. You could try cleaning as suggested though.

 

[sussexman]

I have exactly the same problem Diwali. I was about to take off the pump head but cant work how to take out the 4 bolts that hold it in, they dont seem to be allum keys type. Anyone know what type they are?

 

[sussexman]

OK, I have got the pump head off with allum keys! But the only bit to come off is the part with the electric coil. The bit with the impeller is still attached and doesnt seem to want to be pulled off. Do i just keep pulling?

 

[Johntheo5]

No, I have never removed a A rated pump head, I wouldn't t advise forcing anything off, can you post a photo?

 

[sussexman]

Thanks Johntheo5 for the response. Since my post i have been in contact with Grundfos who have told me to get a replacement from my supplier under warranty, so I will try that route first. If that fails (cos at the moment I dont remember who I got it from!!) I shall take it apart again and post a photo.

 

[Diwali]

Thanks Johntheo5 for the response. Since my post i have been in contact with Grundfos who have told me to get a replacement from my supplier under warranty, so I will try that route first. If that fails (cos at the moment I dont remember who I got it from!!) I shall take it apart again and post a photo.

 

[Diwali]

Sorry! I seemed to have duplicated Sussexman’s post instead of replying!
Good luck with the warranty claim (although you may have issues as the pump has been opened!)
For Sussexman and anyone following this thread this is what I did to solve the issue:
- I removed the pump completely (plenty of YouTube videos on this procedure)
- Opened the pump (4 Allen bolts)
- Removed the impeller unit (pops out with a screwdriver pushed into the hole in the face of the housing - or, if it’s attached to the back of the housing as Sussexman mentioned, just pull it off by hand. (See pic).
- Found the impeller completely stuck - not turning at all despite pushing and turning the screw as recommended in Grundfos clearing blockages guidelines.
- Gently freed the impeller with mole grips taking care not to damage any part of it.
- Turned impeller by hand until it was spinning freely
- Pushed and turned the blockage releasing screw several times checking the impeller was lifting (~5mm) and turning
- Cleaned the unit and ports with dry cloth and reassembled
- Refitted the pump and electrical connection.
- Switched on - all working again!
Observations:
It appears it’s fairly common for these pumps to have ‘blocked’ impellers if they are off for a length of time eg summer. The recommended unblocking method should have worked but in my case the impeller was essentially seized. This indicates to me that I may have further issues with this pump but, for now, it works and has saved me ~ £130.

 

[Johntheo5]

The blocking release doesn't seem very effective?, it mustn't be lifting the impeller if its stuck.
Was the impeller as clean as it looks in photo 3?.

 

[Diwali]

Hi Johnthe05.
Whilst operating the blockage release screw with the pump in situ it seemed to be fine. It was pushing in and turning giving me the impression the impeller was turning. However, switching on again just gave the same ‘blockage’ alarm. Also, there was no hot water being pumped confirming the impeller wasn’t spinning.
After disassembly I did find a small amount of ‘crud’ on the impeller but, even after removing the dirt, the impeller was still seized. I tried pushing the screw but the lifting of the impeller was imperceptible. Also, the screw turned but the impeller didn’t. That I cannot fathom out as they are both at opposite ends of the same shaft so should turn together.
After freeing the impeller, pushing the screw did lift it the required 5mm and it turned when the screw was turned.
I suspect that moisture or dirt (or both) penetrated the bearing behind the impeller enough to cause it to seize hence my opinion that this issue will recur next summer (if the pump lasts that long!)

 

[Johntheo5]

Probably best to give the heating a run for say 5 mins every 2/3 weeks in the summer, I think some heating systems do this now and spin the pump for 10 secs or so if the pump hasn't run in the preceeding 24 hours. I have a 12 year old thermal solar kit and it energises all output relays for 5 secs if they havn't operated in the last 24 hours.