I bought a used Brunco 150 furnace this fall and just finished installing it. I had my first fire last nite and have a thermostat problem. When the thermostat calls for heat, the draft fan starts up. But then after a minute or two the draft fan starts to cycle on and off, like every 10-30 seconds. I took the wires off the thermostat and connected them manually and the draft motor continued to run. So why is the thermostat doing this? Is it specific for a gas furnace?
