kco
Veteran Member
I think there is a good chance it was a smoke explosion caused when he opened the door. I run a 35 year old RSF 101 furnace:
Ardent Energy | Products
which has a thermostatically controlled front draft. Unlike more modern furnaces the draft is either in the closed position (which lets in a small amount of combustion air) or fully open. You can load in a fair amount of wood, but it is important to make sure the front draft is fully-open until all of the wood is burning well. Likewise, when adding wood we need to make sure the front draft is fully-open for about 20 minutes. We do that by making sure the thermostat is calling for heat by raising it even if the room is at the temperature we normally want. The thermostat is one of those "mercury in a bubble" types so you can see what it is doing.
If the wood does not get fully burning and the thermostat closes the front draft, the wood can smolder because there is minimum air entering the firebox. The firebox fills with smoke and gases. When a good flame finally gets going, either due to the thermostat calling for heat or the wood finally gets to the state where it breaks out in flame, there is a gas/smoke explosion. It is not violent, but it is powerful enough that smoke will puff out of the stove pipe joints and chimney draft.
There is a warning with the furnace to be careful if/when opening the door. I've had a few times where it "puffed" as I opened the door due to the fire starting back up. It is not violent but it is a firm push similar to what you might use closing the cover for an air cleaner. Such incidents are likely more risky for stoves where the firebox floor is at the level of the door. For our furnace it is about a foot below the door.
Our way to avoid the "puffing" is to always make sure the thermostat is calling for heat at least 20 minutes after adding wood. If we need to raise the thermostat above where we really want it, we often set a cooking timer to remind us to set it back down so we don't waste wood and don't get the house too hot.
A neighbour had a serious incident with his stove a few years back which I think was caused by a smoke explosion PLUS and incorrectly installed pipe. The pipe joint had been separated where the stove pipe went into the steel chimney liner. His wife called because the house was full of smoke when she returned from town. We rushed down with extinguishers but, luckily, there was no fire, and the cats were still alive despite a lot of smoke. There was a lot of smoke damage which was covered by insurance.
I am sure the pipe separated because the screws joining the pipe to the chimney liner elbow were either not installed or incorrectly installed. It is VERY important to follow all safety recommendations for installations, including the direction of the joints and the number of screws holding those joints. I have my chimney and furnace inspected and cleaned once per year. I always make sure they replace all the screws even though I know they would do it anyway.
Ardent Energy | Products
which has a thermostatically controlled front draft. Unlike more modern furnaces the draft is either in the closed position (which lets in a small amount of combustion air) or fully open. You can load in a fair amount of wood, but it is important to make sure the front draft is fully-open until all of the wood is burning well. Likewise, when adding wood we need to make sure the front draft is fully-open for about 20 minutes. We do that by making sure the thermostat is calling for heat by raising it even if the room is at the temperature we normally want. The thermostat is one of those "mercury in a bubble" types so you can see what it is doing.
If the wood does not get fully burning and the thermostat closes the front draft, the wood can smolder because there is minimum air entering the firebox. The firebox fills with smoke and gases. When a good flame finally gets going, either due to the thermostat calling for heat or the wood finally gets to the state where it breaks out in flame, there is a gas/smoke explosion. It is not violent, but it is powerful enough that smoke will puff out of the stove pipe joints and chimney draft.
There is a warning with the furnace to be careful if/when opening the door. I've had a few times where it "puffed" as I opened the door due to the fire starting back up. It is not violent but it is a firm push similar to what you might use closing the cover for an air cleaner. Such incidents are likely more risky for stoves where the firebox floor is at the level of the door. For our furnace it is about a foot below the door.
Our way to avoid the "puffing" is to always make sure the thermostat is calling for heat at least 20 minutes after adding wood. If we need to raise the thermostat above where we really want it, we often set a cooking timer to remind us to set it back down so we don't waste wood and don't get the house too hot.
A neighbour had a serious incident with his stove a few years back which I think was caused by a smoke explosion PLUS and incorrectly installed pipe. The pipe joint had been separated where the stove pipe went into the steel chimney liner. His wife called because the house was full of smoke when she returned from town. We rushed down with extinguishers but, luckily, there was no fire, and the cats were still alive despite a lot of smoke. There was a lot of smoke damage which was covered by insurance.
I am sure the pipe separated because the screws joining the pipe to the chimney liner elbow were either not installed or incorrectly installed. It is VERY important to follow all safety recommendations for installations, including the direction of the joints and the number of screws holding those joints. I have my chimney and furnace inspected and cleaned once per year. I always make sure they replace all the screws even though I know they would do it anyway.
