Carbon Monoxide after fire goes out

[sdmws6]

Hi everyone,

I have a Dutchwest Majestic Cat Stove from 1996 and it's been burning great. However, every time the fire dies out, my CO alarms go off in the room. I've tried sealing everything and re-gasketed the entire unit. It's very frustrating and I'm not sure how to prevent it. My chimney is an exterior setup that skirts up the side of the house (pics included) so cold-chimney syndrome might be at play here. I can see the little red embers still glowing inside the stove and I'm afraid the gasses aren't rising up the chimney. Has anyone else experienced this problem or know of a fix? Thanks.

 

[kennyp2339]

Maybe add another section of chimney pipe to increase your total run, get rid of the 90 deg bend on the black pipe and replace it with (2) 45 deg pipes.

 

[fatjay]

Is your chimney double wall insulated? Sounds like when the fire gets cool enough, all it takes is a gust of wind to blow the cold air down, the cool air feeds the fire, and blows the byproduct of the burning embers into the house. I get this from time to time, so I try to keep it hot, or shut it down entirely.

 

[sdmws6]

Is your chimney double wall insulated? Sounds like when the fire gets cool enough, all it takes is a gust of wind to blow the cold air down, the cool air feeds the fire, and blows the byproduct of the burning embers into the house. I get this from time to time, so I try to keep it hot, or shut it down entirely.

Yes, it's a Selkirk Super-Pro double wall. How can I shut it down entirely?

Another instance is when the house cools down (around 4 in the morning) and the T-stat kicks the heat on, the central air unit sucks air from the center of the house. It's sucking air from the wood stove and spreading the CO all throughout the house. I guess wood stoves and central air units don't mix?

 

[kennyp2339]

I guess wood stoves and central air units don't mix?

They can exist or co exist, you need to check and see if you stove has an OAK built into it.

 

[fatjay]

I know many people with stoves and central air, who use the central air pump to transfer heat throughout the house.

If you close off all the vents on the chimney it should be pretty much air tight, otherwise you'd be bleeding heat any time you didn't use it in the winter.

 

[velvetfoot]

If you have downdraft even while the stove is warm with red coals, that really is not a good sign.
I wonder if you could keep the chimney warmer by building an insulated chase around it?

 

[fatjay]

Generally you wouldn't have a downdraft while warm, but my buddy has that issue when it gets windy. He has an extremely long chimney as well.

 

[begreen]

Basement stove, yes? It could be that is a negative pressure zone or near-negative. Is something kicking on that could reverse draft like a gas hw heater or a boiler/furnace?

 

[electrathon]

Keep in mind that it is likely not just your furnace causing a downdraft on the wood stove. Your stove is likely causing a downdraft on your furnace and water heater, unless you have electric heat and electric hot water. Can also be caused by a gas dryer or a bathroom/cook stove fan.

 

[sdmws6]

Thanks everybody for all your input!
The stovepipe is cold by the time the CO alarm starts going off, yet there are traces of red embers still left. I now have to make sure the central air handler for the furnace is turned off, both on initial startup of the fire and when the fire starts dying down. Otherwise it'll suck air upstairs from everywhere. The furnace and blower are located in the attic of our bi-level home and the wood stove is downstairs. I have read about negative/positive pressure zones and that very well may be the case. I've done toilet paper tests and it's shown that air is getting sucked into the house through downstairs windows, and pushed outside in upstairs windows. Neutral is between 4ft and 5ft up from the ground on the second floor.
All of our appliances are electric, so I wouldn't think there would be an issue there. I made sure that no blowers throughout the house turn on in the morning, so I don't think they are associated with the CO issue.
Fatjay, I have no vents to close on the chimney. From the stove, the pipe goes up, then a 90 into the wall, into a tee, then up the house. Should there have been some sort of shut-off valve installed?
Kennyp2339, there is no outside air kit for this model stove. The non-cat stove has one, however.
Velvetfoot, I've thought of that, but that's a little over-budget for us at the moment. That probably is the best solution though, before installing a chimney inside the home.

I have noticed when I leave a downstairs window open overnight, the CO alarms don't go off in the morning. The resolution seems to be to provide make-up air downstairs. However, it's freezing in the morning when I leave a window open and completely nullifies the advantages of having the wood stove... HELP!

 

[begreen]

A clothes dryer, kitchen and bath exhaust fans can also exacerbate negative pressure. In the least the stove needs an outside air kit. If that doesn't fix things then consider moving the stove upstairs.

 

[mellow]

Isn't that singlewall pipe going to the thimble? I would upgrade that to doublewall to hold the heat in and hopefully will not have the draft reverse as easily.

You could also install a heat recovery ventilator so the fresh air isn't as cold coming in.

 

[sdmws6]

Mellow, yes it's single wall going into class A through the thimble. I can try switching over to double wall, but I'm afraid to spend the money when I'm not sure that little bit of extra insulation will make a difference. Right when the chimney exits out through the wall, it's completely exposed to the cold air outside, which is where most of the chimney is.

 

[rwhite]

Just a thought to tie into begreen idea of adding an OAK. Is it possible that when the fire is burning active it can draw enough air from other areas of the home and not set off the alarm, as the fire cools it is not drawing adequate air and the concentration of CO increases? It would be my guess that an OAK is the solution.

 

[rwhite]

Another thing that may help folks diagnose your problem is a layout of the basement. How big of a room does the stove sit in? Where all the other CO detectors located and is the one in the basement the only one going off?

 

[sdmws6]

rwhite, I think you're absolutely right. Once the fire dies, the CO starts pouring out the air intakes of the stove due to the cold chimney/negative pressure. Unfortunately, there is no OAK for my model; only the non-cat model. Attached is a basic layout of the home. If the furnace turns on in the morning, the upstairs CO detectors go off around 4-5am, both in the hall way upstairs and the bedrooms. The lower one only goes off if the furnace is off, around 8-9am. We do not load any more wood after 11pm. What happens is the furnace sucks air from the intake in the hallway and dumps heat and CO into the three bedrooms upstairs first along with the living room/kitchen/dining room (because of the proximity of the bedrooms).
Again, thank you everybody thus far.

 

[fbelec]

i would revisit the chimney height. does this happen every night or every once in a while? the chimney cap from the pictures looks to low. it's suppose to be 2 feet higher than the roof within 10 feet. sometimes if the wind even small wind blows across the roof it can hit the cap easy and make a downdraft

 

[sdmws6]

fbelec, I remember the top being pretty high when I was last up there, but I will take some measurements and verify. Thanks. I found this site and took a photo of it, and describes exactly what I'm experiencing. Last night I had the fire die down overnight and left a window open... No CO alarm. But, it was FREEZING downstairs. It really is a shame that's what I have to do.

 

[Smoked]

Can you figure out where the air intake on the stove is and maybe fabricate something to add an adapter to intake outside air? Or, contact the manufacturer and see if there is something they can recommend as a retrofit?

 

[begreen]

rwhite, I think you're absolutely right. Once the fire dies, the CO starts pouring out the air intakes of the stove due to the cold chimney/negative pressure. Unfortunately, there is no OAK for my model; only the non-cat model. Attached is a basic layout of the home. If the furnace turns on in the morning, the upstairs CO detectors go off around 4-5am, both in the hall way upstairs and the bedrooms. The lower one only goes off if the furnace is off, around 8-9am. We do not load any more wood after 11pm. What happens is the furnace sucks air from the intake in the hallway and dumps heat and CO into the three bedrooms upstairs first along with the living room/kitchen/dining room (because of the proximity of the bedrooms).
Again, thank you everybody thus far.

I would not burn in this stove under this condition. The CO detectors are warning you of a dangerous situation. If you love the stove move it upstairs. Or consider replacing it with one that has an outside air connection. Or figure out where it's air intakes are and fabricate an air intake manifold that you can connect a fresh air supply to.

 

[Heatsource]

added chimney height will not fix a stack effect problem
your draft is initiated where the pipe passes thru the building envelope.

if no OAK is avail maybe consider a passive air supply near the stove

 

[revdocjim]

I agree that a retro-fitted OAK system of some sort will probably be your cheapest alternative. There are probably members here who have designed such things for stoves that don't have a ready made kit.

 

[mellow]

You could also install a heat recovery ventilator so the fresh air isn't as cold coming in.

Look into the HRV or ERV systems out there.

http://www.broan.com/products/serie...-systems-d5467c6d-6245-43b0-8f04-3447f6f4b771

 

[Mattawan]

Begreen makes a critical point about negative draft and this can occur with wood stoves as well as with pellet stoves. Fortunately I have a short exit vent on my pellet stoves but a friend encounters negative draft with a basement wood stove which has a long vertical insulated pipe. Al he can do to counter it is to open a basement window a bit.