Grundfos UPS 15-50 pump intermittently trips MCB/RCD – repair or replacement?

[sergii]

Hi,
I have an open-vented central heating system with a Grundfos Selectric UPS 15-50 circulation pump (photo attached).
The electrical supply intermittently trips when the pump is connected and running. Sometimes it runs normally for a while, but then the MCB trips and occasionally the RCD also trips.
I have checked by disconnecting other components and the problem appears to stop when the pump is disconnected, so I suspect the pump may be the cause.
The pump is not seized and appears to run. Could this be an internal electrical fault (motor/winding/insulation), and is this type of fault usually repairable or is replacement the better option?
If replacement is recommended, what modern equivalent would be suitable?
Thanks for any advice.

 

[jj4091]

If it's old just replace it.

 

[mikehammer69]

It’s a common enough issue with those pumps
Replacement usually needed

It'll probably show a low reading if you you IR test it

 

[fixitflav]

If replacement is recommended, what modern equivalent would be suitable?

I had a Grundfos Selectric UPS 15-50 which failed a 2-3 years ago and I replaced it a Grundfos UPS2. It's been fine. There's now a UPS3, which I wouldn't go for, over-complicated and possibly unreliable. For years I swore by Grundfos, but I believe there are now plenty of good makes around. I'm a DIY-er but I've heard on here about, Wilo, DAB Evosta, among others. Maybe somebody can add to the list.