Carbon monoxide incident in ash drawer

[QuarryHouse]

Due to the warm weather I let the stove burn out. I noticed ash and coals were up to the door lip, so I decided to take ash out. Instead of shoveling directly into an ash bucket I decided to try to cool slidy-outy ash drawer on my Chinook 20.2. After some fumbling I got the firebrick out and moved a bunch of ash and coals into the drawer. The stove had been out for 12 hours. In hindsight, there was some warmth in the ash but I didn't think much of it.

2 hours later, my Nest alarmed on carbon monoxide (109 PPM, just above "safe"). It took me awhile to figure out that some of the coals hidden in the ash had re-lit in the ash drawer and had been burning for awhile. The ash drawer had a lot of heat when I pulled it out. Since the ash drawer is sealed off from the firebox, the CO was exhausting into the living room. I haven't had a stove before where the ash drawer did not have a route into the main stove, so I didn't even think of it.

How do others deal with this? Not use the ash drawer? Wet the ash when it goes into the drawer? Immediately empty the ash drawer instead of leaving for the morning as I did?

Also - we're still here and alive. Thank God for detectors.

 

[gzecc]

Nice to know your CO monitor works. I don't have an ash drawer so I can't
comment on safe practices. Stove Manufacturer probably can.

 

[Corey]

Interesting - glad to hear the alarm caught it. I think 'cool' coals are probably one of the biggest and sneakiest producers of CO. If you have 'hot' coals and see that baby-blue flame dancing right above them, then at least you know you're burning most CO into CO2. If you have some active fire, then smoke will also accompany the CO - so that sort of serves as an 'early' alert.

As far as what to do, guess it depends a bit on your situation. I have a pretty good routine of burning the stove one night, raking ash / mostly dead coals into the ash pan the next day, immediately getting another fire going, [repeat 2-3 days], then at some point, I rake ash, empty the pan outdoors and start a new fire. But either way the ash pan is either not really full of 'live coals', ...it is emptied outside, or has a new fire going on top of it , or the ash drawer/stove is closed down and not burning. I suspect trying to time your burning / clean-outs so you are in one of these states and keeping the ash pan / air inlets closed when not in use would go a long way to preventing another alarm.

You might also give some secondary consideration to what caused the 'backdraft'. Ideally, even the 'dead' stove would still have some draft which should be enough to vent the CO. But sounds like yours was flowing back into the room.

 

[gzecc]

I assume you could empty the ash tray back into the stove. Not like it needs to be that clean.

 

[QuarryHouse]

Interesting - glad to hear the alarm caught it. I think 'cool' coals are probably one of the biggest and sneakiest producers of CO. If you have 'hot' coals and see that baby-blue flame dancing right above them, then at least you know you're burning most CO into CO2. If you have some active fire, then smoke will also accompany the CO - so that sort of serves as an 'early' alert.

Definitely.

You might also give some secondary consideration to what caused the 'backdraft'. Ideally, even the 'dead' stove would still have some draft which should be enough to vent the CO. But sounds like yours was flowing back into the room.

I think this is not a backdraft - this is the design of the stove. The ash drawer does not have an airway connected to the main stove and thus any combustion in the ash drawer will go into the room. I think the idea here is to control the air flow into the firebox precisely so the stove can burn very slowly. Having another entryway into the firebox from the ash drawer would probably complicate the airflow.

 

[EatenByLimestone]

I haven’t used an ash drawer since 2009. I was always worried a coal would get stuck on the lip between the plug and stove bottom and not seal right.

 

[Ashful]

Glad disaster was averted, but you really need to read the manual, Quarry!

In a quick glance, I see there are at least five places where your manual says in various language, to remove the ash pan from the house immediately upon use. There's even a BIG all capitals bold text statement with an orange stripe and "WARNING" printed atop, reading "NEVER STORE HOT ASHES IN A GARAGE OR BASEMENT. HOT ASHES WILL GENERATE CARBON MONOXIDE AND / OR FLAMMABLE GASES. THESE GASES MAY CAUSE SUFFOCATION AND POSSIBLE DEATH."

In addition to this, scattered among two other pages they have the statements:

"Ashes must be disposed in a metal container with a tight lid and placed on a non-combustible surface well away from the home or
structure until completely cool."

"ALWAYS REMOVE THE ASH BUCKET IMMEDIATELY AFTER FILLING."

"Ashes must be disposed in a metal container with a tight lid and placed on a non-combustible surface well away from the home or
structure until completely cool."

 

[QuarryHouse]

Glad disaster was averted, but you really need to read the manual, Quarry!

In a quick glance, I see there are at least five places where your manual says in various language, to remove the ash pan from the house immediately upon use. There's even a BIG all capitals bold text statement with an orange stripe and "WARNING" printed atop, reading "NEVER STORE HOT ASHES IN A GARAGE OR BASEMENT. HOT ASHES WILL GENERATE CARBON MONOXIDE AND / OR FLAMMABLE GASES. THESE GASES MAY CAUSE SUFFOCATION AND POSSIBLE DEATH."

In addition to this, scattered among two other pages they have the statements:

"Ashes must be disposed in a metal container with a tight lid and placed on a non-combustible surface well away from the home or
structure until completely cool."

"ALWAYS REMOVE THE ASH BUCKET IMMEDIATELY AFTER FILLING."

"Ashes must be disposed in a metal container with a tight lid and placed on a non-combustible surface well away from the home or
structure until completely cool."

Clearly my bad - I guess I read those as pertaining to an ash bucket external to the stove, which I always took out and emptied. I never thought the ash drawer would exhaust into the house instead of the stack although upon looking at it, it's pretty clear. This seems to make the ash drawer a bit dangerous to use. The handle in the ash drawer folds into the compartment holding the ash so if there are any hot spots you're maybe burning yourself.

I think if I'm deciding to let the stove go out for cleaning, I should leave the thermostat wide open to encourage the last coals to burn themselves out to reduce the chance of something hiding in the insulating ash layer.

 

[sneefy]

It's pretty simple. Think of the ash drawer as a conveyance instead of storage. Fill it, then empty it immediately into a metal container (with tight lid) outdoors.

 

[QuarryHouse]

It's pretty simple. Think of the ash drawer as a conveyance instead of storage. Fill it, then empty it immediately into a metal container (with tight lid) outdoors.

Yeah. I think I'll just shovel into an ash bucket directly and carry it out and skip the middle-man.

 

[Corey]

Definitely.

I think this is not a backdraft - this is the design of the stove. The ash drawer does not have an airway connected to the main stove and thus any combustion in the ash drawer will go into the room. I think the idea here is to control the air flow into the firebox precisely so the stove can burn very slowly. Having another entryway into the firebox from the ash drawer would probably complicate the airflow.

Good point. Your stove is definitely set up different than mine. On my 'antique' the ash drawer is fully connected to the firebox and I made a seal at the outer edge of the ash drawer face. So all my ash / coals are effectively 'inside' the stove and sealed off from the room. Sounds like your newer stove is almost the opposite - ash pan sealed off from the stove, but possibly open to the room.

Anyway, seems like good advice above and sounds like you have the situation figured out!

 

[1kzwoman]

So glad you and family are safe, accidents happen. That’s why working monitors and alarms are necessary.

 

[MMH]

I have the ashford 30.2 with ash drawer, and I just immediately empty it when I use it.

 

[stoveliker]

Yes. Chinook 30.2 here.
Shovel in the ash drawer (if you want to use it) and take it out immediately.
I just shovel into a bucket.

What I didn't understand is the remark about getting the firebrick out. In my stove there is a heavy metal lid with a hook that you can simply lift out with the tool that was shipped with (my) stove. The important part next is to get enough ashes out of the way so that that lid sits nice and tight back where it belongs, otherwise it's an uncontrollable air leak.

 

[MMH]

Yes. Chinook 30.2 here.
Shovel in the ash drawer (if you want to use it) and take it out immediately.
I just shovel into a bucket.

What I didn't understand is the remark about getting the firebrick out. In my stove there is a heavy metal lid with a hook that you can simply lift out with the tool that was shipped with (my) stove. The important part next is to get enough ashes out of the way so that that lid sits nice and tight back where it belongs, otherwise it's an uncontrollable air leak.

Yeah same here

 

[Highbeam]

Yeah. I think I'll just shovel into an ash bucket directly and carry it out and skip the middle-man.

The ash pan is somewhat better, of course it’s not an ash storage pan but an extremely temporary holding station. The reason it’s better, and I think the only reason, is because less ash gets wafted all over the house when using the chute than when dumping shovel loads into a bucket.

 

[Ashful]

I never thought the ash drawer would exhaust into the house instead of the stack although upon looking at it, it's pretty clear. This seems to make the ash drawer a bit dangerous to use.

I've had three older stoves with the ash drawer contained within the firebox envelope, as you describe, and now two with it outside the envelope. I can tell you from long experience that the former is far more dangerous, and I'm glad BK chose to put their drawer on the outside. Too many stoves have been overfired and burned up due to ash pan door gasket leaks, failures, or even breaking off those stupid thin ash pan doors at the hinge at a critical time. It really is an accident waiting to happen. At least with the pan on the outside, the only danger is in your hands, if you choose to leave hot coals in it.

Also, I'm not sure many of us would be hitting consistent ~30 hour burn times with the former design, as even an extremely small air leak in such an ash pan door gasket would ruin a super-low burn rate.

Yeah. I think I'll just shovel into an ash bucket directly and carry it out and skip the middle-man.

I've tried that on several occasions, as some swear by it, but I always found it messy in comparison to the ash pan.

Having said all this, I will also admit the reason I'm so familiar with the manual quotes I had posted above is because I do leave hot coals in my ash pan every week, and have been doing so on two stoves for 7 years. I don't empty it until the next time I need to clean the stove, ensuring all coals are 100% cold before I need to handle it. Based on your experience, all I can guess is that my house is large and leaky enough that it doesn't really matter here. I have 19 CO detectors with the closest just 15 feet from the stove, and none of them have ever gone off due to this practice. Your house is clearly a bit tighter, or the coals in your pan were livelier than anything I've ever allowed into mine.

One thing that has helped me with the use of this ash plug / pan is a 4" round cast iron grate I drop into the ash plug hole, prior to raking ash. This ensures no coals larger than a marble can ever make it into the pan.

 

[stoveliker]

Regarding the mess, I scoop it into my bucket when the stove and flue are still hot. I can see some ash coming up from the basket but it gets sucked into the open stove right away.

(Also tilt the bucket so you can simply slide off the ashes onto the side wall rather than plunk dumping them in. Then almost no ashes get agitated into the air.)

But using the feature designed for it works as well.

 

[Ashful]

Good points, @stoveliker. I usually try to do my ash removal when the stove is dead cold, or as close to cold as it will get during the colder months. So, at least in shoulder seasons, I'm lacking the draft required to keep the bucket method from being messy.

 

[QuarryHouse]

Yes. Chinook 30.2 here.
Shovel in the ash drawer (if you want to use it) and take it out immediately.
I just shovel into a bucket.

What I didn't understand is the remark about getting the firebrick out. In my stove there is a heavy metal lid with a hook that you can simply lift out with the tool that was shipped with (my) stove. The important part next is to get enough ashes out of the way so that that lid sits nice and tight back where it belongs, otherwise it's an uncontrollable air leak.

Not sure it's a firebrick - something heavy with a metal hook on it. I just assumed it was a firebrick. I did sweep the ash away around the opening and made sure it's set back in properly. Back to burning this morning - 26 degrees.

 

[stoveliker]

Yes, that's the metal lid as I have too.
It's fine to use it - it was designed for it. The most important part is the safety commented on above, and the making sure the lid goes back properly so you don't have an air leak. Seems you did the latter right and will do the former right. Then you're good to go. Enjoy!

 

[Ashful]

With regard to the ash plug, I always run the little end of the "L-rod" tool around the groove between the firebrick and ash plug hole, to clean out any compacted ash before re-installing the plug. Then I use the same tool to turned onto it's flat side to sweep any remaining ash into the groove around the perimeter of the plug. Belt and suspenders, I suppose.

There was a story from a member about 8 years ago, who seriously over-fired their stove, due to an improper reinstallation of an ash plug. I don't even remember if it was on a BK or another brand, as ash plugs are common across several brands, but it left a lasting impression on me.

 

[MMH]

On this topic, in addition to the great advice above, this is another reason for me to keep some ash left in the box during cleaning. I’ll spread it out over the bottom as usual but will pay attention and cover my ash plug religiously just in case I did miss something in the grove. Whether this is legit or not it gives me peace of mind (to some extent) that I’m covering any potential air leaks that could happen from the plug.

 

[QuarryHouse]

I've had three older stoves with the ash drawer contained within the firebox envelope, as you describe, and now two with it outside the envelope. I can tell you from long experience that the former is far more dangerous, and I'm glad BK chose to put their drawer on the outside. Too many stoves have been overfired and burned up due to ash pan door gasket leaks, failures, or even breaking off those stupid thin ash pan doors at the hinge at a critical time. It really is an accident waiting to happen. At least with the pan on the outside, the only danger is in your hands, if you choose to leave hot coals in it.

Also, I'm not sure many of us would be hitting consistent ~30 hour burn times with the former design, as even an extremely small air leak in such an ash pan door gasket would ruin a super-low burn rate.

For sure. Having a full ash drawer in my Jotul F3 was one of the only ways to get it to burn a little slower.

Based on your experience, all I can guess is that my house is large and leaky enough that it doesn't really matter here. I have 19 CO detectors with the closest just 15 feet from the stove, and none of them have ever gone off due to this practice. Your house is clearly a bit tighter, or the coals in your pan were livelier than anything I've ever allowed into mine.

Maybe - when I bought the house the T-111 siding had rotted at the base due to improper flashing at the deck. I ripped it off, added two inches of XPS and house wrap and re-clad. The house has only casement windows, which are pretty tight. I've never done a blower test to see how tight it really is, but the CO detector was probably 15 feet from the stove. I think it's more likely that there was more life in the coals that fell into the drawer than I thought. I'm still trying to get my head around a stove that has live coals 12 hours after it's been dead and black.

One thing that has helped me with the use of this ash plug / pan is a 4" round cast iron grate I drop into the ash plug hole, prior to raking ash. This ensures no coals larger than a marble can ever make it into the pan.

I was thinking about this in the shower this morning - maybe there should be a grate that could slide open or something, although it could easily get clogged. Did you buy the cast iron grate?

 

[Ashful]

Yes, I bought a 4" round cast iron shower grate from McMaster Carr. I can dig up the p/n for it if you want to buy the same.

The round works nicely, as the corner holes left by it allow me to easily retrieve it using the BK poker tool. I did end up using a cutoff tool to remove every second "bar" in the grate, to get it to pass ash and pea-sized coals without letting thru anything much larger than a standard playing marble. The gap left around the corners (round grate in square hole) are also about the right size to let ash and small bits thru, but not anything of a concerning size.

Here's my procedure:

1. Plow a clean spot in front right corner of stove, this is where I'll set the plug.
2. Use poker tool to pull plug, and set in front right corner of firebox.
3. Use poker tool or gloved hand to set 4" round grate into plug hole.
4. Plow ash over grate. As ash falls thru and coals remain, plow the coals toward a clean corner, to keep.
5. When plug hole appears full, jiggle pan drawer in/out 1" a few times, this will distribute ash in the pan and make room for a lot more. Repeat 2x - 3x until nearly full.
6. Remove grate with poker tool, then use poker tool to plow groove around the plug hole.
7. Replace plug, then use poker tool on flat side to plow some ash into groove around plug.