The spill switch is a little metal sensor that trips if it gets too hot.
If the spill switch trips the boiler will not fire even though the pilot light is lit.
If the spill switch is tripped it is very simple to reset it, just press the little button between the wires and you should hear a click, if you do not hear a click, it's possible it was not tripped and this is not the problem.
If you do hear a click and the boiler fires, YOU ARE NOT DONE!.
Something caused the spill switch to trip.
The most common reason for a spill switch to trip is the vent is obstructed.
vent is obstructed, carbon monoxide is
going to back up into your home.
This is what the spill switch is designed to prevent.
Chances are the spill switch will trip again.
If this happens check your roof vent to see if birds or bees or some other creature has built a nest in the vent pipe. High levels of snow have been known to prevent boilers from venting, remove snow from around the vent cap, if your vent cap is missing your vent may be full of leaves. Make sure your vent is 100% clear.
Another reason your spill switch may trip is a defective vent damper.
The vent damper is designed to stop the boiler from firing if the damper is not 100 % open but sometimes the end switch on the vent damper sticks and sends a signal that the damper is open, when it is not.
DO NOT bypass the spill switch, carbon monoxide will kill you and your family.
As I said earlier many older boilers do not have spill switches or vent dampers, so if your vent becomes obstructed you will have a dangerous situation, with no safety device to shut the boiler down.
Maybe you should have a new Burnham boiler installed.
Having a Carbon Monoxide detector is a must if you have any gas appliances.
To get it done fast and right please use the 24/7 Help Line