Biasi M90e 24s

[roseylee]

what can it be ? once ch is hot boiler keeps firing for 10secs then shuts off for about 30 secs then fires again will keep doing this constantly (flow temp 75 return temp 68).When heating ch from cold it seems to work fine
Has had new heating temp sensor new pcb & new ignition pcb in last 2 weeks
any ideas ?

 

[zk]

the dhw sensor

 

[roseylee]

will the dhw sensor affect chang as it works fine for hot water

 

[bengasman]

If it fires every 30 seconds, the pcb was not done correctly.
If my memory serves me right, this model had had upgrades