We have a strange issue with our gas heater.
If the room thermostat temperature setting is higher than the room temperature it ignites normally. But periodically 2-3 times a day or night we hear constant clicking. When we look at the thermostat the room temperature and thermostat temperature setting shows the same temperature. The clicking can go for long time so what we end up doing is increasing the thermostat temperature when the clicks continue and this makes the burner ignite and work. We called the heating guys few times but they were coming when we did not have the clicking. They checked the heater and did not find any issue. We could not manually trigger this issue. It's very annoying especially at night. We have to go away for a week in December so really need to fix the issue prior to the trip.
Did anyone have similar problem?

Thanks,
Julia

Sounds like the sensor is going bad. I had a similar problem where the heater kept trying to ignite but with a bad sensor the heater would not stay on, so the heater kept clicking on and off.

Thank you Pready, It's a good possibility that sensor is bad. What confuses us is that the heater ignites perfectly well when we manually adjust the thermostat temperature to be few degrees higher at the time it starts clicking.