I have an intertherm Propane Gas Furnace. We are on the coast, so we do not need the cooling unit. We seem to be experincing the furnace coming on, and then shutting off before it warms. Usually only running for a minute, then shuting off for a minute. Each time the furnace burner ignites. What could be the problem?

Lots of possibilities. Start small & (hopefully don't) work your way up. Check/replace air filter if needed. Try this: turn off power, remove "R" & "W" wires from thermostat, and connect together. Turn power on and observe. If previous short/frequent cycling pattern continues, furnace is malfunctioning. If furnace sustains continuous operation, the thermostat is the culprit.