I have a Beckett oil furnace and a home depot "Rite Temp" digital thermostat. When the house temp drops below the set temp the thermostat sends a signal to start furnace, but furnace does not start. When I press the rest button on the stack the furnace starts, heats the home to the set temp and then shuts down, but it won't automatically restart when house temp drops again. So it seems that the thermostat shuts down the furnace but doesn't start it. What could be the problem?

Thanks

Probably the thermostat. Remove the thermostat wires from the furnace and jump R and W. If you do this a few times and the burner runs the thermostat is at fault. I will have to ad that you should not have to be reseting the reset control so it is possible the burner is also experiencing a problem since the stack is a safety switch and should not activate if the burner starts and rund every time. The stack control only drops out when the burner does not start to the burn with in the set time range.