Grundfos water circulator not circulating

[Oilers]

Hi, I have a Grundfos UP15 42RUC7 circulator which doesn't appear to be working. the impeller moves freely when I spin it manually but when there is power tot he device all I hear is humming but the impeller doesn't turn even though it does not appear to be stuck. Also, oddly I can not find my model # anywhere for this Grundfos. The closest I have found is UP15-42BUC7 but you can see clearly in the picture I have attached that my model is an "R" and not a "B". Any help would be appreciated. As mentioned - power appears to be at the unit and the impeller is not turning even though I can spin it freely by hand - thanks

 

[SJB060685]

Has the capacitor been checked?

 

[Oilers]

Has the capacitor been checked?

Nope-but wouldn’t the impeller still spin even if the capacitor was faulty with power running to the unit and you can audibly bear the unit humming?

 

[Gasmk1]

what does it feed the only difference with B will be it is Bronze impeller used for hot water seconday circulation

 

[Oilers]

what does it feed the only difference with B will be it is Bronze impeller used for hot water seconday circulation

It is just used for in-floor heating water circulation. Had no idea the B just meant bronze! Thanks!

 

[SJB060685]

Nope-but wouldn’t the impeller still spin even if the capacitor was faulty with power running to the unit and you can audibly bear the unit humming?

A humming/buzzing noise is typical audible sound of a cap failed or a seized motor. The motor will spin by hand as it is with a failed cap but trying to start a single phase motor without an auxiliary winding and a cap is impossible, once rotating it would be fine but not to start.

 

[Darren Jackson]

I would try fitting a new capacitor. Pick one up from your local plumbers yard for around £10. It sounds like yours has failed and not starting the impeller. Or swap the head if you don't want to fit new parts into the existing head control box.