boiler fires up and then cuts out after 3minutes

[bondy10]

--------------------------------------------------------------------------------

i have seperate heating and water boilers- the heating boiler is an Ideal Classic FF230 and the pump for it is a Grundfos ups 15-50. If i turn the heating on the boiler fires up for a few minutes and then cuts out. it will not fire up again unless i switch it off and leave it for a while but i have the same result again,fires up and then cuts out.
i felt the pump which seemed VERY hot and was wondering if the pump could be to blame for this. i tried turning the shaft with a screw driver and it seems fine,also the the timer seems to work ok.

 

[cowley]

Sounds like the pump, when you say you turned the shaft was that with the system turned on?.
When you remove the chrome screw in the centre of the pump with the system on it should be spinning if not remove the black cover where the 3 speed control is and check for live on the brown wire beware 240volts if live but not spinning you need a new pump.

 

[bondy10]

thanks for that cowley. the pump was switched off when i tried to move the spindle. i will check the voltage as per your instructions and post the result. thanks again

 

[superdupergasman]

Get a screw driver in the top and turn the spindle it may just start up again. it would only be a temp fix however as it will jam again in the future.

 

[bondy10]

thanks super.... will give it a go.

 

[bondy10]

ok-fitted new pump,same model as previuos, and now the upstairs radiators are hot but the down stairs ones are cold and the new pump seems noisier than the old although we have heating now,to an extent,so the pump was to blame but why the extra noise and cold rads?

 

[bondy10]

ok,i seem to have cured the problem,i hope!
read somewhere on this site about trapped air around the pump,so i removed the centre screw and replaced it to remove any air and turned off the upstairs rads leaving the downstairs rads on and this cured the noisy pump and cold rads downstairs. Thanks to Cowley and Super... for their help.