Worcester Bosch 28cdi Boiler - Spontaneous Combustion.

[Reginaut]

Hello All,

As above, I have an old Worcester Bosch 28cdi Combi Boiler, the issue;

Due to fluctuating HW output temperatures end various knocking/rumbling sounds, I was advised to change the 'plate' which I did. Upon start up 9switching the machine on - and without selecting ANY service, the machine 'appears' to sense that a tap has been turned on and immediately goes into HW mode, including ignition. This is somewhat worrying as all that heat has to go somewhere? I say again, no service has been selected. In the interests of safety, I have been turning the machine off again a bit sharpish.

I'd be obliged if you could point me in the right direction, with Thans in advance.

 

[Stuckinarut]

Does the boiler have a preheat function? Could it have been from opening the cold inlet?

 

[dilalio]

Have a hot tap open when you power up the boiler. Let it run and get hot water from the tap. Turn tap off and see if demand ceases and boiler stops.

 

[kidgreen61]

DHW preheat switched on, as said above.

 

[sugarlips]

bet you its the micro switch fitted wrong on the divertor valve spindle

 

[Reginaut]

Many thanks evereyone for your input, I am obliged.

Somewhat disgruntled, I left the machine off overnight, returned the following morning, switched the power on and ..... it just sat there, in its ready state, no lights on (except power) then selected the various services manually, and ........ all working perfectly.
I should stress NOTHING was done to the machine in the interim, other that leaving it idle overnight, Happy days!

Kind regards and Merry Christmas to All.