After several false starts (or maybe false finished) the furnace is working as it should. Travis replaced an electronic board. The old board was designed for one try to ignite. If it did not light, the fan would continue to run blowing cold air. The new board will try three times for ignition (which seems to be catching first time all the time). If it were not to light, the fan would only run long enough to clear the LP fumes and then shut down the fan.