24CDI hw + ch tempremental. Already had new pump but problem is reoccuring.

[armyash]

Hi guys

I had a thread back in October, my brothers boiler was playing up. HW and CH would only work for a little while, then it would make a clunking noise and shut off.

He asked me to go round tonight as the HW was playing up.

It sometimes doesn't get hot at all (the hw light does come on). Or it gets too hot but then the boiler will make a clunking noise and go off.

Also on the ch side it will fire up and run for a short while, 60 secs then go off. Sometimes it will only work if i press the over ride button but then doesn't stay on for long.

I changed the pump back in October and it has worked ok up to now (although they say the hw does sometimes play up)

Tonight the pump was getting very hot again like last time.

Also I took the dhw heat ex off and cleaned that.

What should I be looking at?

This is driving me pretty mad.

 

[armyash]

I have read these symptoms could be the cause of faulty thermistors?? What do you think?

I'm not overly convinced as the banging is making me think there's something else.

I don't really want to start throwing parts at it no matter how cheap. Just want to get it sorted.

 

[kris]

Hey ash, it's nothing to do with the thermistors , you have a circulation problem , I think the pumps gone and when the boilers firing up the water isn't moving ,,, did u check to see if pump was turning by taking out the centre screw ? I know u changed it but my money's on da pump,
could be a blockage somewhere or a closed valve ,

 

[armyash]

I said to my brother it sounds like a blockage.

Yes the pump was spinning. The new pump is 5 months old could it have broken that quick?

Will be going back saturday to investigate.

Any other suggstions on what i can try?

 

[Millsy 82]

Is it the old Cdi? Partial blockage in diverter?

Burner pressure ok?

 

[armyash]

Burner pressure was ok.

Will check the diverter next time.

Thanks