ravenheat 82e

[woody7]

similar problem to mrricko
boiler will start up ok but will only run for 5 secs before cutting out and restarting itself. think possilbily problem with flame sensor (lead) but could someone please explain how these work in detail, want to understand what is happening

thanks

 

[kevplumb]

simple enough a flame conducts and rectifys ac in dc out

if you think its iffy change it

hardly in arm and leg territory

 

[Slugbabydotcom]

When gas burns its a chemical reaction which creates a small amount of current as well as the heat and light of the flame This Small voltage is detected through the lead at the pcb.
No voltage = no flame.
Voltage = flame.
Pcb needs to know theres a flame there so it can stop letting gas out if the burner isnt lit
Sometimes they corrode, sometimes the porcelain cracks and sometimes the wire melts against the boiler parts and the signal doesnt get back to the PCB. Thats all that goes on that would warrant a replacement but it hardly ever happens.
What does happen is that the flame does not reach the sensor for whatever reason.