Ongoing problems with Trane 5-burner natural gas furnace new circa 2002. First day running this season I noticed cold air blowing. Lockout code (2 flashes). Restarted and heated at call for heat but stopped short of temp goal, then lockout again. Putzed with this for a day or two and then no gas at all. From reset (power off, power on) this is what happens when there is a call for heat:
1)inducer runs
2)hsi glows
3)"click" from solenoid in control board, 27 volts to gas valve
4)no gas that I can discern
5)hsi dims
6)inducer stops within a minute or two
This cycle will continue 2 more times then 2-flash lockout
The fact that there is a click and 27 volts to the gas valve *at the correct time* should mean that flame sensor, limiter and inducer pressure are all satisfying the board. So I tested the w.c. at outlet and got 3.3. I adjusted to printed spec of 3.5. Had no effect. I installed a new gas valve. No effect. Tested w.c. *inlet* on new gas valve, 5.5 which is at the low end of things but I've never read anything that says the valve won't operate with lower than 7 w.c. inlet pressure or anything. I have read that low inlet pressure causes problems, suggesting that gas valve would continue to work. When the gas was working in the limited fashion that it was it was a robust flow to the burners. I could increase the inlet pressure by shutting the water heater and stove but this really shouldn't change anything. From a purely intellectual standpoint, does anyone have any theories as to what the problem might be?
1)inducer runs
2)hsi glows
3)"click" from solenoid in control board, 27 volts to gas valve
4)no gas that I can discern
5)hsi dims
6)inducer stops within a minute or two
This cycle will continue 2 more times then 2-flash lockout
The fact that there is a click and 27 volts to the gas valve *at the correct time* should mean that flame sensor, limiter and inducer pressure are all satisfying the board. So I tested the w.c. at outlet and got 3.3. I adjusted to printed spec of 3.5. Had no effect. I installed a new gas valve. No effect. Tested w.c. *inlet* on new gas valve, 5.5 which is at the low end of things but I've never read anything that says the valve won't operate with lower than 7 w.c. inlet pressure or anything. I have read that low inlet pressure causes problems, suggesting that gas valve would continue to work. When the gas was working in the limited fashion that it was it was a robust flow to the burners. I could increase the inlet pressure by shutting the water heater and stove but this really shouldn't change anything. From a purely intellectual standpoint, does anyone have any theories as to what the problem might be?
