No heat

An online help site lead me to believe the problem was the gas igniter. After ordering that and installing it I discovered that wasn't the problem. I took a look at the schematic which is in the electrical compartment and found that there is more than one thermal breaker. I found the other one, ordered and installed the part and had it running within 30 minutes. I had to access the back of the unit, remove the back cover with a socket wrench, unscrew the thermal breaker and re-install the new one with no special tools.