Last night I was woken up by my smoke detector telling me that there was carbon monoxide and that if I didn't do something then it was going to scream at me. I opened windows and got the ceiling fan going, but that didn't shut it up until I used the fan to blow out the RMH for a few minutes. It never did get to screaming so I guess it never got to serious levels.
I made some changes to the RMH's mass this summer & fall and have also changed some processes.
What was different yesterday:
I used my new Wonder Wash for the first time and hung up the load of socks on the newly installed clothesline near the RMH barrel. That almost certainly wasn't a cause.
I fried up some homemade Fritos using tallow in a pot. I never smelled burning, but I didn't actually measure the temp of the fat.
I burned up a couple cups of old tallow early on in the burn. (Because every bit of BTUs I don't need to cut and split is a win, right?)
What's been different this year:
There is more cob mass around the burn area, and it is likely better sealed. I have slightly less radiant heat from the burn barrel and it feels like more heat from the mass.
I haven't needed to use a fan to help with drafting anywhere near as much as last year.
I realized that the grey water drain doesn't have a trap and the drain in the shower is a pretty straight shot (one turn) to the drain pipe exit. I started covering the drain with a sandbag a month ago to help keep it from becoming a heat loss.
I noticed that when there is some wind that the RMH exhaust was blowing in cold air when it wasn't being used, so this season I've been covering the top of the feed tube with a piece of hardyboard once I'm done burning.
I have noticed that this year there's more ash and it has larger chunks.