TL;DR; Bird in the flue fan. Vent feeds into the same chimney as my fireplace (I don't know if it heads to the same pipe within the chimney.) Do I need to do something to prevent this in the future?
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I have a cursed, CURSED flue venting system in my crawl-mounted 80% Goodman Furnace. I've learned to just about expect the dreaded Three Blinks of Doom almost once a year.
In the seven years I've been in this house, it's needed the following repairs.
- Mud dauber somehow got down the chimney, through the horiz. flue vent pipe, and plugged up the vinyl tube to the pressure switch. (Home Warranty: $50 deductible. It's a shame I didn't save their invoice, because he's the only HVAC guy that has ever NOT screwed up an install or repair.)
- Next time it broke, it looked fine to me every time I manually reset it. Repair guy came, the pressure switch fell apart when he fiddled with it, he replaced. ($150)
- When it wouldn't fire a couple days later... it turns out the pressure switch, while flimsy, wasn't the problem. The bearings on the motor had failed. I discovered this by successfully reviving the motor by whacking it the end of the shaft with my Mag-Lite during startup. Naturally this was discovered Friday night, meaning many trips into the crawl space to whack the motor throughout the weekend. Being the Husband-Powered Thermostat is no fun. Repair guy comes out again and replaces the fan. (Naturally this took two trips, because he didn't think to bring a new fan when I told dispatch what the problem was.) ($400)
- The next season, it turns out the repair guy didn't use wire ties like he was supposed to, and the cooling vanes for the motor ate through one of the wires for the pressure switch. I patch them up with wire nuts and hang them out of the way. (DIY) I vow to never use that repair guy again, crossing another company off the list.
- A year or two later, the tubing for the pressure switch broke off at the end. I remount. (DIY)
And now... today!
Time for the first furnace run of the season. I turn on the t-stat and... silence. (If I listen carefully, I can hear the flue blower from inside the house.) Sure enough, the Three Blinks of Doom. Again. I get the cover off, and notice the motor won't start... just hums. Again. I repeat my patented motor revival technique of percussive maintenance. It fails. I fiddle with the cooling vanes and manage to somehow push past the obstruction. I fire it up again, and it makes a god-awful whining noise.
I pull out the trusty tools (Took the combined efforts of my trusty 6-in-1 tool, a massive flathead screwdriver, and a couple sockets attached to 8" of extensions) and remove the fan. Ick... the whining noise was bird feathers slapping against the fan blades. I extract the unfortunate avian and dispose of the corpse.
I try to disassemble the flue pipe and am unsuccessful, but I do check the elbow attached to the furnace and there's no nest in it nearby. I put things back together and success! Heat!
Now, the question: Is some part of my chimney missing/rusted out, or is this just an occasional inevitable hazard? I'm thinking I need a repair somewhere, because if this was like the furnace in my attic (which is the 20-something-yr-old original) there would have been no flue pressure switch to notice the problem, which would have, at best, flooded my crawl with exhaust gas. And maybe some CO for good measure.
********
I have a cursed, CURSED flue venting system in my crawl-mounted 80% Goodman Furnace. I've learned to just about expect the dreaded Three Blinks of Doom almost once a year.
In the seven years I've been in this house, it's needed the following repairs.
- Mud dauber somehow got down the chimney, through the horiz. flue vent pipe, and plugged up the vinyl tube to the pressure switch. (Home Warranty: $50 deductible. It's a shame I didn't save their invoice, because he's the only HVAC guy that has ever NOT screwed up an install or repair.)
- Next time it broke, it looked fine to me every time I manually reset it. Repair guy came, the pressure switch fell apart when he fiddled with it, he replaced. ($150)
- When it wouldn't fire a couple days later... it turns out the pressure switch, while flimsy, wasn't the problem. The bearings on the motor had failed. I discovered this by successfully reviving the motor by whacking it the end of the shaft with my Mag-Lite during startup. Naturally this was discovered Friday night, meaning many trips into the crawl space to whack the motor throughout the weekend. Being the Husband-Powered Thermostat is no fun. Repair guy comes out again and replaces the fan. (Naturally this took two trips, because he didn't think to bring a new fan when I told dispatch what the problem was.) ($400)
- The next season, it turns out the repair guy didn't use wire ties like he was supposed to, and the cooling vanes for the motor ate through one of the wires for the pressure switch. I patch them up with wire nuts and hang them out of the way. (DIY) I vow to never use that repair guy again, crossing another company off the list.
- A year or two later, the tubing for the pressure switch broke off at the end. I remount. (DIY)
And now... today!
Time for the first furnace run of the season. I turn on the t-stat and... silence. (If I listen carefully, I can hear the flue blower from inside the house.) Sure enough, the Three Blinks of Doom. Again. I get the cover off, and notice the motor won't start... just hums. Again. I repeat my patented motor revival technique of percussive maintenance. It fails. I fiddle with the cooling vanes and manage to somehow push past the obstruction. I fire it up again, and it makes a god-awful whining noise.
I pull out the trusty tools (Took the combined efforts of my trusty 6-in-1 tool, a massive flathead screwdriver, and a couple sockets attached to 8" of extensions) and remove the fan. Ick... the whining noise was bird feathers slapping against the fan blades. I extract the unfortunate avian and dispose of the corpse.
I try to disassemble the flue pipe and am unsuccessful, but I do check the elbow attached to the furnace and there's no nest in it nearby. I put things back together and success! Heat!
Now, the question: Is some part of my chimney missing/rusted out, or is this just an occasional inevitable hazard? I'm thinking I need a repair somewhere, because if this was like the furnace in my attic (which is the 20-something-yr-old original) there would have been no flue pressure switch to notice the problem, which would have, at best, flooded my crawl with exhaust gas. And maybe some CO for good measure.
