Central Heating Pump Working?

How do I tell if my central heating pump is working?

Lick it ........ Does it taste like a goer ?

Grab hold of it ........ Prolly will feel it vibrating a lil

Hmm maybe it isn't working then. Don't think it's vibrating but then I don't know how much it should.

Boiler is cycling. Radiators upstairs hot but downstairs cold. With boiler switched off but CH and HW controls on, the spindle in the pump is spinning - does that mean the pump is kaput?

Any other way to tell for sure if the pump's had it?

Take head off and watch/feel impeller spin. You should feel it spinning when you remove the screw on the front but doesnt nesesarilly mean the impeller is spinnung aswel.

Thanks. I now think that the pump is working - with the boiler off but the CH and HW controls on I could hear / feel that the pump was running.

I also spotted that the pump has three speed settings. It was on 2 and I've turned it up to 3. When I changed the speed there was an obvious response from the pump.

Putting the pump up to setting 3 seems to have eased the problem with the boiler cycling / cutting out (presumably its taking the heated water away from the boiler more quickly so that the boiler temperature regulator is not shutting it down so frequently).

Can anyone give any guidance on what pump setting I should be using? Does the fact that I need to be on setting 3 suggest that there is a sludge or other circulation problem?