Heating L E D. lights up and pump starts but no gas ignition. The system will stay on but no heat. Sometimes it will light and be ok for a while then the pump will intermittanly just stop then start again.
There is a thermistat just above the pump when i disconnect one of the leads and put it back on it will ignite for a while then stop. Could this be the problem.

Michael Mucha, October 2012