Help w/ Post Fire Carbon Monoxide

[spacemanspiff]

Hi. First post for me. I've got a Woodstock Soapstone Fireview wood stove that has tried to killed my family a couple of times. The usual course of events is we have a fire in the evening letting it burn out overnight. Then the next day, usually in the afternoon, all of the carbon monoxide alarms go off. First time it happened we thought it was a fluke. But by the second or third time we realized we had a problem.

First step was to get the chimney lined. The chimney is external brick. So we had someone come out and install a liner and insulation. That made it a little better. But we still kept getting carbon monoxide buildup.

Second step, we got an outside air kit installed. Again, seemed to help for a bit, but then we got the alarms again.

Our interim solution is to leave the window nearest the stove cracked--all the time. This obviously is less than ideal for both security and home efficiency purposes.

Some other information about our situation, the chimney is the proper height for the roof--though are house is on a hill side. But we've never had back puffing issues while the fire is actually burning. It just seems that at some point the fire cools enough that flow in the chimney reverses and the embers begin to smoulder it turn pumping out CO.

The woodstove is on the first floor of our two story home. There is no basement. The house is on a slab.

I've considered a collar warmer or draft inducer, but people on here tend to have negative reviews of the same.

I'm open to any thoughts people have!

 

[begreen]

This could be an issue of terrain and the chimney location. My SIL had this situation with a fireplace. Openings and leaks on the second floor can cause negative pressure in the floor below. Are all second floor windows closed when burning? Is there an attic vent or doorway that needs to be sealed for winter?

Reverse draft can be dangerous. Keep those CO detector batteries fresh.

 

[spacemanspiff]

This could be an issue of terrain and the chimney location. My SIL had this situation with a fireplace. Openings and leaks on the second floor can cause negative pressure in the floor below. Are all second floor windows closed when burning? Is there an attic vent or doorway that needs to be sealed for winter?

Reverse draft can be dangerous. Keep those CO detector batteries fresh.

Oh yeah. One in every room hardwired with backup battery.

Second floor windows always closed. There is a pull-down to the attic. The pull down has weatherstripping around its perimeter and then there is a insulation board "hood" over the whole opening. Plus we had the attic air sealed to deal with some moisture issues two years ago. So while the attic entry isn't airtight, its probably as close as I can get it without extreme measures.

 

[begreen]

This could be a tough one if you are also fighting cool air descending into a valley during the night.

Sometimes the stove pipe connection can lessen draft. Is the Fireview rear-vented into the chimney or does the stove pipe go up for a few feet first and then a 90? Can you describe the stove connection ot the chimney in detail? Can you post a shot of the installation?

PS: Is there a flue thermometer on the stove pipe and if yes, what temp is it reading when the CO detectors go off?

 

[spacemanspiff]

This could be a tough one if you are also fighting cool air descending into a valley during the night.

Sometimes the stove pipe connection can lessen draft. Is the Fireview rear-vented into the chimney or does the stove pipe go up for a few feet first and then a 90? Can you describe the stove connection ot the chimney in detail? Can you post a shot of the installation?

PS: Is there a flue thermometer on the stove pipe and if yes, what temp is it reading when the CO detectors go off?

I’m guessing the later. Here’s a photo:

 

[spacemanspiff]

Just saw the question about the thermometer. Yes usually have a magnet one stuck on the pipe (not in the photo though).

Usually the stove and flue are room temperature by the next morning. If you open up the box you could probably feel some heat coming off the ashes. But not enough to register on the thermometer.


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[Highbeam]

Are there gas burning appliances in the home?

 

[spacemanspiff]

There’s a propane boiler in another room. But it has its own intake.


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[SculptureOfSound]

Sounds like you would be better off with the outside air being disconnected from the stove while burning and acting as a passive air intake. That way when the stove has cooled to the point where the house was drawing air down the chimney and leading to the CO, it would draw air in from the disconnected OAK instead.

It would basically be an open window but more secure. Not sure how hard it is to connect and disconnect - if difficult maybe just leave it disconnected and plug it up when the stove is not and use and then open it when burning.

 

[xman23]

So, do you have a poor draft during the burn?

 

[spacemanspiff]

Sounds like you would be better off with the outside air being disconnected from the stove while burning and acting as a passive air intake. That way when the stove has cooled to the point where the house was drawing air down the chimney and leading to the CO, it would draw air in from the disconnected OAK instead.

It would basically be an open window but more secure. Not sure how hard it is to connect and disconnect - if difficult maybe just leave it disconnected and plug it up when the stove is not and use and then open it when burning.

The OAK is specific to the stove so it’s pretty well integrated. I could disassemble some pipe I suppose to try it out.


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[spacemanspiff]

So, do you have a poor draft during the burn?

Nope, no problems while burning.


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[spacemanspiff]

So at this point does everyone think I would be justified in using one of the “band aid” fixes and installing a flue warmer or flue fan? And if so, any reason to go with one over the other?


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[peakbagger]

I would go at it another way. Put in air to air heat exchanger on the house and balance it so the house is slightly positive. If the house is slightly higher pressure than outdoors you will not get backdrafting.

 

[brenndatomu]

Are there kitchen and/or bath fans being used that cause the reverse flow to start?

 

[fire_man]

You said the chimney is the correct height for the roof but that does not mean its high enough for your stove setup or environmental/terrain conditions. I added 2 feet of pipe to my liner and it made a world of difference.

Can you add temporary height to your liner and see if that cures the problem?

Also make sure the cap for the cleanout "T" seals well.

 

[moresnow]

On another note. Why is your fireview burning completely out overnight? Just curious! A thought.

 

[spacemanspiff]

Are there kitchen and/or bath fans being used that cause the reverse flow to start?

Yes. But once we released we had a problem we made sure to stop using them when the fire is dying or the day after.


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[spacemanspiff]

On another note. Why is your fireview burning completely out overnight? Just curious! A thought.

I can certainly keep it going overnight but I still get the CO problem when it eventually burns out.


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[spacemanspiff]

You said the chimney is the correct height for the roof but that does not mean its high enough for your stove setup or environmental/terrain conditions. I added 2 feet of pipe to my liner and it made a world of difference.

Can you add temporary height to your liner and see if that cures the problem?

Also make sure the cap for the cleanout "T" seals well.

I’ll double check the cap.

Regarding temporary extension, I assume it should be insulated right? Just trying to think of what I could use.


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[Highbeam]

For test purposes, uninsulated is fine. Even a cheap chunk of metal hvac duct from the hardware store would work.

 

[Highbeam]

How do you know it is a draft reversal and not just bad air from outside or from another appliance? Does anybody know if the fireview outside air connection is relatively sealed to all of the stove inlets? My bk and hearthstone were 100% supplied from the oak so a reversal would just dump smoke outside via the oak.

I’m still thinking it’s just the gas boiler kicking on as the house cools after the fire dies. The CO from the gas boiler could trip your detector.

Fortunately, I’ve never had a flue flow backwards unless I had a big exhaust fan on in the home. It’s hard to imagine how it could happen with an oak.

 

[spacemanspiff]

How do you know it is a draft reversal and not just bad air from outside or from another appliance? Does anybody know if the fireview outside air connection is relatively sealed to all of the stove inlets? My bk and hearthstone were 100% supplied from the oak so a reversal would just dump smoke outside via the oak.

I’m still thinking it’s just the gas boiler kicking on as the house cools after the fire dies. The CO from the gas boiler could trip your detector.

Fortunately, I’ve never had a flue flow backwards unless I had a big exhaust fan on in the home. It’s hard to imagine how it could happen with an oak.

Unfortunately, or fortunately depending on the circumstances, our CO alarms are tied to an alarm service that sends the fire department each time they go off. And if the fire department comes they make the propane people come out too. Then the propane folks stalk all over the place with their hydrocarbon and CO detectors. And after the third visit and inspection the boiler was definitively ruled out as a culprit, haha.


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[fire_man]

I used a spare section of SS pipe but a short section of regular stove pipe should work and is $13.
The correct long term solution is a Class A pipe but the adapter and pipe are more expensive.

(broken link removed)

 

[begreen]

For test purposes, uninsulated is fine. Even a cheap chunk of metal hvac duct from the hardware store would work.

If it's just for a test, get a 3-4' piece of 6" light gauge warm air duct like Highbeam suggests. On a calm couple days, remove the cap and push the crimped edge of the duct into the top of the liner. Try it out during the day with a smaller fire so that you can observe the full burn cycle. You might also want to alert the fire dept that you are conducting these tests and to call first if they are receiving an alarm. (Or can the phone connection to the dept. be temporarily cut off?) If this makes little difference, then I'm with peakbagger with installing an HRV to put a slight positive pressure in the space. If it makes a notable difference then a proper, permanent chimney extension is the answer.

Can you post an exterior full house (and hillside) picture of the chimney?