RUUD Gas furnace not firing
#1
02-29-16, 02:20 PM
RUUD Gas furnace not firing
80% Ruud gas furnace just stopped firing, or fires intermittently, but won't stay on. (Fires one in ten times, this just started two days ago) This unit is UGDE-10QAGS 100,00 BTU manufactured in 1989. To start it was working fine 4 days ago and since then I would have to shut off unit and turn back on to get it to work. This was usually the case in the morning when I would wake, after it worked fine all day the day before. then two days ago it would start this during the day, I would turn it off and turn on and it worked again until the next day. Yesterday I was able to get it restarted once, then it would not restart, and now I can't get it started again. Although it did start while I was testing the voltage, suspecting the gas valve might be the issue, but now I don't think it's the gas valve.
So, here is what I have done/ observed so far. Ignition sequence, thermostat calls for heat [check], inducer fan kicks on [check], inducer actuated vacuum switch [check], HSI turns on [check], gas valve doesn't actuate.......checked voltage, when valve should actuate, voltage drops from around 4 volts to 0 volts. The one time I did get it to fire today was during testing and I did see it register the 24 volts that I was supposed to see. Thinking it might be the ignition control board, but I was hoping to get some insight from any professionals on here.
Thanks in advance and let me know if you need any more info. To help make a determination.
So, here is what I have done/ observed so far. Ignition sequence, thermostat calls for heat [check], inducer fan kicks on [check], inducer actuated vacuum switch [check], HSI turns on [check], gas valve doesn't actuate.......checked voltage, when valve should actuate, voltage drops from around 4 volts to 0 volts. The one time I did get it to fire today was during testing and I did see it register the 24 volts that I was supposed to see. Thinking it might be the ignition control board, but I was hoping to get some insight from any professionals on here.
Thanks in advance and let me know if you need any more info. To help make a determination.
#3
02-29-16, 02:34 PM
Member
Good troubleshooting so far. With all intermittents, I always advise checking that all screw connections are tight and plugging and unplugging all connectors a couple of times, looking for corrosion on the terminals. (Make sure power is off while doing all this).
Examine the control board for any obvious damage or burning, and look for any bad solder or cracked foils on the board.
Examine the control board for any obvious damage or burning, and look for any bad solder or cracked foils on the board.
#5
02-29-16, 04:06 PM
Cleaned any terminals that might have even been a little corroded, but my experience as an electronics technician told me that wasn't the issue. Even after cleaning everything good still having the same issues.
#6
03-02-16, 02:47 PM
Banned. Rule And/Or Policy Violation
Replace the ignition control board.
The control board should turn on the HSI and leave it on for 30 seconds or so to heat up, then switch on 24 VAC to the gas valve to get gas for the HSI to light.
You have verified that the ignition control is failing to turn on the gas valve reliably ---- so you have a bad ignition control.
Don't feel too bad about that. The ignition control operates a variety of different functions in the furnace. By replacing the board, you replace ALL those other systems too, which should allow you to avoid other problems in the future.
The control board should turn on the HSI and leave it on for 30 seconds or so to heat up, then switch on 24 VAC to the gas valve to get gas for the HSI to light.
You have verified that the ignition control is failing to turn on the gas valve reliably ---- so you have a bad ignition control.
Don't feel too bad about that. The ignition control operates a variety of different functions in the furnace. By replacing the board, you replace ALL those other systems too, which should allow you to avoid other problems in the future.
#7
03-07-16, 04:28 PM
Update on this issue
As I was able to conclude from my troubleshooting and with the confirmation from SeattlePioneer, after installing the new Ignition Control Module, the furnace fired up immediately. I waited a few days to post, just to make sure, but that was definitely the issue. System has ran through many cycles and the digital thermostat has gone through its multiple temp changes (morn, day, evening, and night are all different temps) and not one failure or even a hiccup.
Thanks again for anyone who replied and had an idea for me to try.
Thanks again for anyone who replied and had an idea for me to try.
