Chimney explosion?
Posted: Thu Mar 08, 2018 8:02 pm
Here's how it went down.
Jamie calls me around 3:45 while she's getting Ian off the bus. She says she heard a very loud bang and the basement was smoky and the smoke alarm was going off. It seemed like there was no fire so I had her go in and shut off the water heater and furnace. The smoke had already seemed to dissipate and the smoke alarm had already shut off. I don't think either the furnace or hot water heater were running at the time she flipped them off. But it was good that she did.
Things seemed to stabilize so I went to a meeting and left work around 5pm.
When I got home I saw evidence that something had exploded, possibly in the chimney. The basement (and house) had a pretty strong diesel/oil smell. The following things had happened:
- Flue dampers on both the hot water heater and furnace pipes were blown completely off.
- Both clean out trap doors were blown open
- The big furnace flue pipe had blown apart (at a joint). See pics.
Furnace flue pipe damper. This is actually tightened down and it still blew off. Some of the cement had blown out from around where the pipe enters the chimney. This is a good one but not the worst part. Still, this joint blew apart and was hanging by one screw. The furnace would have been exhausting into the basement at this time if it was running. Good thing I had Jamie shut it off in case it tried to turn on. Here's some sketchiness. This is the cleanout below where the 8" furnace flue enters the chimney. This door was blown open as pictured. This looked like a normal pipe of oil soot. But inside I found a brick. I think this brick blew out of....somewhere in the chimney. Can't say I've ever opened this but I suspect it happened today. Blown off hot water heater flue damper. Blown open cleanout for the living room fireplace. Then I fired up the hot water heater which seemed to be working just fine and seems clean inside. I did not detect like a bunch of flue gas blowing out from that damper hole, which would indicate a chimney restriction. Inside the flue where the damper would normally go. I don't see anything amiss here. Here is a shot inside the cleanout for the living room fireplace. Extremely clean. More shots of the other cleanout with the brick. Shoveled a lot out and then vacuumed. Inside the flue pipe that goes into the chimney. Also seems clean in here. Inside the flue pipe looking back toward the furnace. Also clean though I had cleaned this not long ago. Then I fired up the furnace and checked for blow back and restrictions. Seemed fine, too.
Furnace has been running and other than the smell, everything seems normal.
I have no idea what happened, but both systems seem to be running clean and I think something happened in the chimney, which is kind of sketchy. But, it also currently does not seem to be restricted so maybe something built up, got hot and actually exploded and cleaned itself out?? That is messed up.
I talked to Jamie just now and here's a little more. Around 3:40 and was cleaning up some boxes. A few minutes later, she heard the "explosion" (which she described loud bang, probably also the dampers hitting the ground). She went back into the basement and it was all smoky and the smoke alarm was going off. Shortly after this she called me.
I have had my chimney inspected a while back and I already knew it was sketchy but something else happened and I'd like to know what. As of right now, things seem to be working pretty normally.
The only other thing it could have been was an ignition of raw fuel either in the hot water heater or furnace, where the burner blows a bunch of oil in, fails to shut off, and then somehow ignites it creating an explosion. This seems unlikely because it seems like it came from the chimney, rather than the hot water heater or furnace. Seems to have effected them equally.
Jamie calls me around 3:45 while she's getting Ian off the bus. She says she heard a very loud bang and the basement was smoky and the smoke alarm was going off. It seemed like there was no fire so I had her go in and shut off the water heater and furnace. The smoke had already seemed to dissipate and the smoke alarm had already shut off. I don't think either the furnace or hot water heater were running at the time she flipped them off. But it was good that she did.
Things seemed to stabilize so I went to a meeting and left work around 5pm.
When I got home I saw evidence that something had exploded, possibly in the chimney. The basement (and house) had a pretty strong diesel/oil smell. The following things had happened:
- Flue dampers on both the hot water heater and furnace pipes were blown completely off.
- Both clean out trap doors were blown open
- The big furnace flue pipe had blown apart (at a joint). See pics.
Furnace flue pipe damper. This is actually tightened down and it still blew off. Some of the cement had blown out from around where the pipe enters the chimney. This is a good one but not the worst part. Still, this joint blew apart and was hanging by one screw. The furnace would have been exhausting into the basement at this time if it was running. Good thing I had Jamie shut it off in case it tried to turn on. Here's some sketchiness. This is the cleanout below where the 8" furnace flue enters the chimney. This door was blown open as pictured. This looked like a normal pipe of oil soot. But inside I found a brick. I think this brick blew out of....somewhere in the chimney. Can't say I've ever opened this but I suspect it happened today. Blown off hot water heater flue damper. Blown open cleanout for the living room fireplace. Then I fired up the hot water heater which seemed to be working just fine and seems clean inside. I did not detect like a bunch of flue gas blowing out from that damper hole, which would indicate a chimney restriction. Inside the flue where the damper would normally go. I don't see anything amiss here. Here is a shot inside the cleanout for the living room fireplace. Extremely clean. More shots of the other cleanout with the brick. Shoveled a lot out and then vacuumed. Inside the flue pipe that goes into the chimney. Also seems clean in here. Inside the flue pipe looking back toward the furnace. Also clean though I had cleaned this not long ago. Then I fired up the furnace and checked for blow back and restrictions. Seemed fine, too.
Furnace has been running and other than the smell, everything seems normal.
I have no idea what happened, but both systems seem to be running clean and I think something happened in the chimney, which is kind of sketchy. But, it also currently does not seem to be restricted so maybe something built up, got hot and actually exploded and cleaned itself out?? That is messed up.
I talked to Jamie just now and here's a little more. Around 3:40 and was cleaning up some boxes. A few minutes later, she heard the "explosion" (which she described loud bang, probably also the dampers hitting the ground). She went back into the basement and it was all smoky and the smoke alarm was going off. Shortly after this she called me.
I have had my chimney inspected a while back and I already knew it was sketchy but something else happened and I'd like to know what. As of right now, things seem to be working pretty normally.
The only other thing it could have been was an ignition of raw fuel either in the hot water heater or furnace, where the burner blows a bunch of oil in, fails to shut off, and then somehow ignites it creating an explosion. This seems unlikely because it seems like it came from the chimney, rather than the hot water heater or furnace. Seems to have effected them equally.