If pilot is lit I
check to see if there is power. coming
to boiler If no power I check breaker.
ok so we have power and pilot is lit Boiler is set up to be hot, but boiler is cold Why? most boilers have 24v gas valves, some have 120v but most have 24v this power is supplies by a transformer the power goes through the transformer through the aquastat then through all the safety switches, rollout switches and spill switches any one of these can be tripped and or burned out. not all boilers have these safety devices the older one we worked on above does not have any. Thank you for taking the time to visit my site.