Worcester Greenstar 35Cdi problem finding

[iamlee2002]

Hi all, posting this on behalf of my dad.

He has got a Worcester Greenstar 35cdi (approx 12 years ago fitted), Recently hes been having issues when calling it for heating. It sends the signal to the boiler, the boiler fires up, you can see the temp rising goes up over 100 then shuts off again. This is very temperamental, other times it then heats up no problem circulating the water. Do you think this could be the pump? Also when using the hot water from tap it throws the boiler off again sometimes the heating dont come back on. We have checked the diverter valve that is functioning correct. When touching the pump it is extremely hot, you can feel it spinning a little, We have checked its getting power from the PCB which it is. It's just unusal as sometimes it will work, other times its a no go.

I would like your advise before taking any action, I have had 1 bad experience with an engineer before, i know not all are like it but when my vailiant had no hot water from tap it ended up costing me to the engineer £400 and the problem wasn't fixed, in the end i repaired it myself and all it had been was a black rubber hose clogged up, replaced the pipe (£8) myself and worked again.

Many thanks for your time and replies in advance.

 

[ollski]

When they overheat the pump runs in bursts until the temperature drops. Could be pump, could be stepper motor. Get a decent engineer in who will guarantee his work...or worcester

 

[iamlee2002]

Thanks for the reply. An example of what happens:
Set thermostat on boiler to max heating kicks in great. Leave it on until radiators heat up as soon as we put the hot water on the tap and switch it off the boiler display shows temperature rising all the way to 100 then get u1 to u7. Pump at this stage is untouchable as it's scorching. The stepper motor is fine as the diverter valve moves no issues

 

[Simon144]

Hi iamlee did you get to the bottom of this problem as my 35cdi also 12 years old is doing the exact same thing.