Real Plumbing Help Plumbing and Heating Answers

First the thermostat, Although they do fail, Most of the time it is not the thermostat. Many people think it's the thermostat and replace it. I look at the Thermostat last.
The First thing I do Is see what the temperature of the boiler is. If it is hot between 160 and 190 % f I know the boiler is working. If it is cold, I check to see if it is set up as a hot boiler (one that is always hot) Or a cold boiler (only gets hot if there is a call for heat) if it is set up as a hot boiler but is cold. I check pilot light. 


Peerless relief valve