I have a Janitrol GUE100-5 natural gas furnace WITH A SPARK IGNITION WHICH MALFUNCTIONS. This furnace was installed by the builders in our "spec" house in 1990, and I have since been told by furnace repair people that it was one of the cheapest furnaces available at the time. It has a DOE AFUE of 74.1% and the exterior is not even painted. Every 2 to 3 years I have had to have the circuit board and thermocouple replaced for a cost of about $150, because the SPARK IGNITOR WILL RUN FOR A MINUTE OR SO AND THE FURNACE WILL TIME OUT AND NOT START. After the circuit board (a United Technologies Electronics Controls, intermittent pilot, 100% shut-off, ANSI Z21.20, 24 VAC, 60 Hz, 150 mA, 90 sec lockout, 5 minute retry) and thermocouple is replaced, it will still "buzz" for about 20 to 30 seconds, but the furnace burner will light. When this problem first surfaced about 5 years ago, not even replacing the circuit board and thermocouple worked. The furnace repairman was on the phone with Janitrol (Goodman Manufacturing) for two hours trying to figure it out - then the Janitrol person told him to run a ground wire to the gas supply manifold, which then made it work. It worked for a couple of years, then did the same thing - started to "buzz" for a minute or so then shuts off. Does anyone know what could make the United Technologies circuit card and thermocouple go bad so fast? I watched the repair, and a new thermocouple alone did not work - it needed the new circuit board also. I have had no other electrical problems in my house, and have had the electric utility out to check all of my house wiring.