Andy, thank you for responding to my request. I live in the North east (New Jersey) We had a really mayor snow storm it dummped 2-1/2 feet of snow and the first thing I did was check the exhaust and intake for the furnace. It was not blocked. I don't hear any girgling at the drip leg, but did find a small drop of water at the tubing connected to the exhaust side. (from the pressure diferential switch)I pulled off the tubing but it din't have any water in it. i do have a lennox a/c unit (2 ton) and a april air humidifier which also drains into the condensate line and goes to the same condensate pump. I don't have a round thermostact. I have the Honeywell Chronotherm III electronic setback thermostat. The green led on the Johnson ignition control only blicks a few seconds during start up, after that it glows steady. When the ignition control locks out the led shuts off and remains off until I shut down the power and turn it back on again. When the units starts it starts right away. The unit has never been pressure tested, and the only other thing replace was the flapper gasket, not the the flapper valve itself. last week on 2/21/03 I borrowed a fiber optic scope from a friend and looked inside the unit. I was able to see the spark plug and the sensor. I discovered that there is a square nut threaded to the back of the sensor were the sensor wire is attached too. the nut was very loose and I could turn it by hand. I tighten the nut but the following day the gas company came down and replaced the ignition sensor again. (I had an appointment already set up) "I have a service contract with the gas co." Do you think that maybe the problem was caused by the loose wire? Do you still recomend the pressure testing and the flapper replaced. Thanks again. Waiting for a responce.