UK Problem with Grundfos UPS 3 pump?

[garyevans]

Half an hour later I am on CC3 venting the system...

 

[ShaunCorbs]

Hi Shaun. This worked perfectly. Until last night. Every day we had a quiet pump and hot water and central heating worked great. Last night, I was upstairs when I heard the heating come back on and the pump was making that noise again. I turned the heating off, put it back on and tried CC3 to vent the system but nothing would make that noise disappear. Decided to turn heating off and wait til this morning. Same issue. What I can't work out is why it would be great for a full week and then just stop. You mentioned cavitation. What causes this and how do I avoid it? I am not a plumber by the way. Thanks.

This is very strange

Cavitation means no flow, can be caused by no flow / shut valves etc or dirt in the impella

My recommendation would be to split the pump and see if there’s dirt in the impella

 

[garyevans]

This is very strange

Cavitation means no flow, can be caused by no flow / shut valves etc or dirt in the impella

My recommendation would be to split the pump and see if there’s dirt in the impella

Thanks Shaun. What does that mean? I presume a professional needs to do that.

 

[ShaunCorbs]

Thanks Shaun. What does that mean? I presume a professional needs to do that.

If the valves shut off above and below the pump it’s just 4 Allen screws

Depends how handy you are