Potterton combi 80 runs constant

[stevesw2]

I have a Potterton Combi 80 it's about 10 years old now and for the last few months when you turn the power on the boiler fires and carries on running for a few minutes. untill it goes into lockout this happens without hw or heating on.When you run the hotwater it runs very hot then lockouts after a while but enough to fill a bath.There is also a problem with the heating the rads heat up for about 5 to 10 minutes then boiler locksout.The boiler makes quite a loud noise near the top when it locksout after startup.
Any ideas please.

 

[ianmcd]

your boiler is stuck in HW demand mode there is a current thread running on here just now you need a wax capsule replaced on your diverter valve an easy fix if you are good at DIY

 

[Agile]

Your boiler might be locked into DHW demand but thats not caused by the wax capsule. Your capsule is obviously OK because you can get CH.

Your boiler seems to have two faults, a spurious demand for heat and something causing it to go into lockout!

Have you ever had it serviced?

Tony

 

[stevesw2]

Would the heating come on if the dhw was stuck on the diverter?
I was thinking maybe the flowswitch stuck open making the boiler think a tap is on.
Someone said it could be the pcb but am not sure.what makes the boiler lockout is it overheating?

 

[ianmcd]

do you have a dripping HW tap anywhere in your property ? I would also check the DHW flow switch