If you can light and maintain flame for longer period of time than 7 to 10 seconds, then the ignition board is sensing flame is present but then dropping out flame after a little time of running.
- Burner is not adjusted properly and must be adjusted until flame is mostly blue with small portion of orange.
- Pressure is too high and pulling away from burner face or ground rod.
- Chassis ground is not properly bonded and ground is intermittent.
- Modulating valve is not functioning properly and closing down too far. The modulating valve is designed to hold a given temperature or set point that can be adjusted. If the valve cannot hold a temperature then the power element on bottom of valve needs to be replaced.
- Check fuel supply for flow restrictions.