Grundfos UPS2 15-50/60 circulating pump problem

[John.g]

If its the model I think it is then a bit ambiguous re venting so perhaps its detecting "air" on occasions?

Startup
The pump must not be started until the system has
been filled with liquid and vented. Furthermore, the
required minimum inlet pressure must be available at
the pump inlet. The system cannot be vented through
the pump.
The pump is self-venting and does not require venting
before startup.

In speed III, the pump is set to run on the maximum curve under all operating conditions. See fig. 14.
Quick venting of the pump can be obtained by setting the pump to speed III for a short period.

 

[Muttontop]

Thanks for all the replies, problem has now been solved by replacing the control box that sits on top of the pump (replaced with one from another Grunfos UPS2 pump). The pump now starts without any issues straight from fire up. Replacing the control box is a very straight forward and simple job. Once the top black cover is removed there are 2 screws which locate the control box to the pump. Once these are removed the control box just pulls off, it connects to the pump via a plug. Replacing is simply a reverse of the above. Only problem now is locating a replacement control box for the pump I canniballised. The Grundfos part number is 98662219. I can't find any reference to this part anywere on the internet or in the Grundfos web site. Anyone any suggestions where I might get a replacement other than from another pump?

 

[ShaunCorbs]

You won’t they don’t sell it separately

 

[Phillip Capron]

Had similar problem ups2 pump ticking/pulsing and not starting. Then after a while (12 mins at the last attempt) it would start and run normally. Meanwhile the boiler (WB FS30cdi) would run, overheat and cut out. This would repeat until the pump started.
Solution:Fitted a new pump,-ups3. Operation now normal. It would appear that the old pump was 11years old so it didn't owe me anything.
HTH.

 

[ShaunCorbs]

Had similar problem ups2 pump ticking/pulsing and not starting. Then after a while (12 mins at the last attempt) it would start and run normally. Meanwhile the boiler (WB FS30cdi) would run, overheat and cut out. This would repeat until the pump started.
Solution:Fitted a new pump,-ups3. Operation now normal. It would appear that the old pump was 11years old so it didn't owe me anything.
HTH.

Capacitor at fault likely