Baxi solo 3 overheat

[evo antony]

I have just moved house installed there is a baxi solo 3 pfl40. I am experiencing problems wth overheat and only seems to occur when heating is selected on? boiler stat is approx a third of the way clockwise. A new control stat and overheat stat have been fitted to the boiler. Rads do get hot and seems to be working fine with boiler clicking in and out but then occasionally trips? Should there be a overrun on the pump once room stat is reached, I have manually turned down room stat to min this shuts down pump along with boiler no overrun of pump?
Hope you can help thanks.

 

[Agile]

I think there is a pump over run.

First thing is to see where the pump is connected to.

Also see if the boiler connection block has a marked connection for the pump and if anything is connected to it.

Tony

 

[gas4you]

Yes there is a pump overrun of approx 5-6 minutes, controlled by the boiler pcb.

 

[evo antony]

thankyou for your replys much apprieciated I will look into this and perhaps replace boiler pcb. Does the overrun apply to both hot water and central heating, also can you purchase timeclock/programmers with incorporated pump overrun its just that I was thinking of changing to a modern digital model and thought perhaps this may resolve overrun by doing this?
Thanks again.

 

[gas4you]

The boiler doesn't know whether it is on for heating or hot water. Pump live is wired directly to boiler terminals.

 

[evo antony]

Checked out wiring to time clock what a rats nest! though after seeing this may be worth taking a look at boiler wiring(pcb) this was lacking pump output cables but found 2 cables in N (boiler mains) and 2 cables in E (boiler mains)? Disconnected 2nd pair at boiler traced to timeclock then placed into pump output. Magic we now have a 5.5 min pump overrun and so far has stopped overheat problem. Just now have the job of tidying up. Thanks again for your replys you have been a great help.