Originally Posted by progmac
are you sure your gas water heater or gas dryer flue doesn't have a dead bird or other obstruction in it?
I have not visually checked any exhaust lines from the house, although I will say that, first, the dryer has continued to vent well (safely excluding this as an option). Second, while an obstruction in the heat line will go uninvestigated, there are a few points to consider:
1) I do have caps on the chimney that appear to be clear of nesting material.
2) If there was an obstruction, it has cleared, which leads to the question of how? If there were a dead bird in the line, nothing has removed it.
3) My heat isn't running, so the line is only venting from the water heater, which leads me to believe there is presently a low exhaust volume.
4) The timing is still incredibly suspicious. This implies the line was obstructed at the start of the fermentation and then cleared once fermentation was complete.
Originally Posted by MaxStout
How old is that CO detector? They should be replaced every 5 years or so.
The alarm is getting close to five years old. It's getting close, but it certainly is not old, damaged, filthy, or otherwise impaired. That's a good point, though, and I'll replace it soon.