OK, did I just create a negative draft?

[rosencra38]

I've had a small fire going in my quad 4300 since I got home 5 hours ago and I just put in a few rather large logs to get things going for the nights long burn. After burning for 10-15 minutes, if that, I started to smell wood/smoke in the house. I couldn't figure out where it was coming from but as I opened the stove door to double checked that it was completely shut the smoke just poured out of the stove and into the house. I had this happen to me this morning as well but didn't think much of it as I got the fire going strong and then all was good. After another 5 minutes of this though I noticed more smoke in the house then while looking things over further I noticed that I had smoke coming into the house from just below where the stove pipe goes through the ceiling. I checked outside and I had LOTS of white smoke coming out the top of the chimney. At this point I closed the dampers all the way in an attempt to shut everything down before the entire house is full of smoke and the smoke alarms go off. I decided I would take out one of the large pieces of wood that was sitting on top and took it to my outside firepit. After I did this I noticed that the coals along with other logs almost immediately started a fire again with the dampers completely closed and the door shut. I let things go for a couple minutes then opened up the damper a little then opened the door and had no smoke escaping the stove door this time. I also had no smoke escaping from up above. I'm wondering if I created a negative draft by adding too much wood into the stove, it couldn't be because it was cold since I had a fire going for 5 hours already. Or, could it be that I am not getting enough draft with the colder weather we are having now? This is the coldest it has been all season this far and I've only had the stove for a couple months. I haven't had this issue at all this season so far and I've filled the stove right up almost every night with no problems. Could my problem also be with the size of the log? Any ideas what I might have done wrong or did I already figure it out?

 

[LLigetfa]

It was probably a culmination of factors and letting the flue temp drop too low and then overloading creating too much smoke, put it over the top. None of those actions actually caused a negative pressure but rather too much of a positive pressure inside the stove with not enough draft to move the smoke.

There are probably some steps you could take to increase the pressure in the house like sealing leaks that let warm air out and NOT sealing leaks that let cold air in.

 

[madrone]

There are probably some steps you could take to increase the pressure in the house like sealing leaks that let warm air out and NOT sealing leaks that let cold air in.

How do you manage that? Post little exit and enter signs in red and blue?

 

[MacPB]

How do you manage that? Post little exit and enter signs in red and blue?

I think you can seal up the windows/doors tight in the upstairs and away from the stove. Leave windows and doors with draft downstairs and near the stove. Maybe use some of that plastic sealer that you heat up with a blow dryer to get a tighter seal on upstairs windows.

Just a thought.

 

[LLigetfa]

There are probably some steps you could take to increase the pressure in the house like sealing leaks that let warm air out and NOT sealing leaks that let cold air in.

How do you manage that? Post little exit and enter signs in red and blue?

It's easy to find the places that cold air comes in since you can feel the cold draft. People tend to plug those up first and then think they are done. The air infiltration is make-up air and necessary.

The leaks where warm air escapes are harder to detect. For those you need to use a smoke pencil and observe the air movement. Warm air leaking out causes a negative pressure as do exhaust fans and clothes dryers.

If you plug all the leaks letting warm air out, you will have less cold air leaking in.

 

[begreen]

Throwing big logs on the fire doesn't create negative draft. You may have created a smokey smoldering fire due to damp wood or too large splits, etc. But that's not negative draft. What's the flue system on this stove? When was it cleaned? Tomorrow morning go out and check your flue cap and see if the screen looks like it's plugging up.

Normally when you are adding wood, try to first rake the hot coals to the front and center. Then add a small couple splits, north/south about 3 or 4" apart and put the large splits on them facing east/west. That should ignite the small splits quickly which in turn will start the bigger splits, (unless they are damp inside).

 

[staplebox]

I am sure there are better burning brains around here but I would ask/suggest-
Where is your chimney - inside our out? Insulated? How tall?
Do you have outside air hooked up?

Sounds like you just smothered the fire and lost the draft. Too much wood on top of not enough coals. Keep playing with it. If this happens again try opening the draft and adding a few pieces of loosely crumpled newspaper to kick start things again.

 

[LLigetfa]

Throwing big logs on the fire doesn't create negative draft...

We can agree on that. The rest is semantics...

A negative pressure is only negative in the face of a greater (positive) pressure. Overloading the coals when the draft was less than ideal generated more smoke than could draft up the chimney. It's like when you stumble while drinking beer. It starts to fizz and you can't drink it fast enough so it comes out your nose.

Fizzing beer and billowing smoke take the path of least resistance.

 

[PaulRicklefs]

Could my problem also be with the size of the log? Any ideas what I might have done wrong or did I already figure it out?

Never mind the draft thing for now. You simply put in too much wood and closed the damper too soon which is a no no. If you load it up to the nines let it burn for a bit before banking it down and do not shut the air off completely. This will allow the fire to burn slowly instead of getting snuffed out.

The reasoning for your smoke escape is more complex but let me explain. You had coals which tells me the stove was nice and hot. Hot air takes up more room than cool air. When you put in your cold logs and closed the damper you created somewhat of a vacuum as the fire cooled off and the air inside contracted. The smoke has nowhere to go. It will draw air from wherever it can. It will often get air from the loose connections in the flue pipe and even from the top of the chimney if it's bad enough. Once it gets enough air the smoke will reignite causing a spike in pressure that is too great for the chimney to handle and will come out of every crack or gap in the system.

This is a common problem. Best thing to do is burn small and burn hot, all the time. Keep that chimney warm to promote good draft. If you do load it up, let it burn for a while before banking it down. Nothing worse than cold logs and no air. Not to mention it creosotes the heck out of the chimney system.

Meanwhile, in the effort to not be a hypocrite, it's time to load up my blaze king for the night.. better let it burn for a while before I kick it back.. just enough time for a nightcap...

Happy burning,

 

[oconnor]

It's easy to find the places that cold air comes in since you can feel the cold draft. People tend to plug those up first and then think they are done. The air infiltration is make-up air and necessary.

The leaks where warm air escapes are harder to detect. For those you need to use a smoke pencil and observe the air movement. Warm air leaking out causes a negative pressure as do exhaust fans and clothes dryers.

If you plug all the leaks letting warm air out, you will have less cold air leaking in.

Make up air is necessary yes, but it shouldn't come at the expense of air infiltration. An EPA stove running full throttle uses very little make up air. (in the order of 40cfm, or half the output of a cheap bathroom fan)

That said, your house is a system of systems, and when your chimney backflows, your house has become a better chimney than your flue, and other systems contributed to it.

Rosencra 38 - tell us about your stove setup - external flue? basement installation? Do you have an outside air kit installed? Is your flue lined with stainless liner or a masonary clay tile flue?

All of these affect the total issue of the stove system interacting with the other systems in your house. Give the Guide linked in my signature block a read - pay attention to "stack effect" when you do - stack effect is what caused your house to fill with smoke, and can be avoided with some simple practices, like openning an outside door should you ever notice you house filling with smoke again - sometimes this is all you need to do to stop the problem once it occurs.

Avoiding it, however, is a way better plan - that we can help you with if you give us some details

 

[rosencra38]

It's easy to find the places that cold air comes in since you can feel the cold draft. People tend to plug those up first and then think they are done. The air infiltration is make-up air and necessary.

The leaks where warm air escapes are harder to detect. For those you need to use a smoke pencil and observe the air movement. Warm air leaking out causes a negative pressure as do exhaust fans and clothes dryers.

If you plug all the leaks letting warm air out, you will have less cold air leaking in.

Make up air is necessary yes, but it shouldn't come at the expense of air infiltration. An EPA stove running full throttle uses very little make up air. (in the order of 40cfm, or half the output of a cheap bathroom fan)

That said, your house is a system of systems, and when your chimney backflows, your house has become a better chimney than your flue, and other systems contributed to it.

Rosencra 38 - tell us about your stove setup - external flue? basement installation? Do you have an outside air kit installed? Is your flue lined with stainless liner or a masonary clay tile flue?

All of these affect the total issue of the stove system interacting with the other systems in your house. Give the Guide linked in my signature block a read - pay attention to "stack effect" when you do - stack effect is what caused your house to fill with smoke, and can be avoided with some simple practices, like openning an outside door should you ever notice you house filling with smoke again - sometimes this is all you need to do to stop the problem once it occurs.

Avoiding it, however, is a way better plan - that we can help you with if you give us some details

OK, on with day 2 of this issue. I read the replies and did want to let everyone know that I have been sealing the windows in my house with the 3m shrink wrap stuff. Although, when the problem first started yesterday morning I hadn't done any new windows, last night I did the two in my boy's bedroom. Anyway, today we are having the same issue. House is full of smoke, luckily we have a carbon monoxide detector... Now, on to my stove setup. My home is a 2000 sq ft double wide. The stove is setup in the living room which is pretty much in the center of the house where a fireplace used to be until I ripped it out this summer. My flue comes out the top of the stove up through the ceiling (this is the point where the smoke is coming into the house by the way). Being a double wide I do have an outside air kit installed which goes out the back of the stove and through the floor into the crawl space below the home. I believe the flue is all stainless. We've had the stove for just over two months now and never had a problem until now. We are burning seasoned pine right now, the same we have burned all season. No difference in the size of the wood chuncks or the way that I am running the stove. I'm really at a loss here and am starting to get worried that I am putting my wife and three kids (5,2,1) at risk here. Could I possibly have something plugged up??? Whenever I open the stove door to add wood or move something around I immediately get a lot of smoking pouring out of the stove and into the house. I've even had the fire build very quickly when the door was open and the flames came out of the stove... Could my stove be malfunctioning??? Thanks in advance for all of your help.

Worried in Michigan.

 

[fossil]

I think you need to get your stovepipe/chimney looked at/cleaned out pronto, and I think you need to take a trip into the crawl space to inspect that OAK and maybe put a critter screen on it (if not already installed). Somethin' ain't right here, and that somethin' has to do with the free flow of combustion air into the stove and/or the free flow of combustion gases out of the stove. In any case, it's pretty scary. In a mobile home installation, the performance of the stove should be completely independent of the performance of the home, in terms of air movement in or out of the dwelling from any other source. Rick

 

[rosencra38]

I think you need to get your stovepipe/chimney looked at/cleaned out pronto, and I think you need to take a trip into the crawl space to inspect that OAK and maybe put a critter screen on it (if not already installed). Somethin' ain't right here, and that somethin' has to do with the free flow of combustion air into the stove and/or the free flow of combustion gases out of the stove. In any case, it's pretty scary. In a mobile home installation, the performance of the stove should be completely independent of the performance of the home, in terms of air movement in or out of the dwelling from any other source. Rick

Damn internet service, I went and typed up the whole reply to this and then got disconnected and lost it all.... Anyway...

My outside air control is pushed through the floor and into the crawl space but I believe it is only pushed into the insullation and not actually pushed all the way through into the crawl space below. Under my floor there is the insulation and then there is a black liner (basically a big tarp) that seals everything in and holds up the insulation. The OAK never protrudes out from this liner. The dealer that installed the stove told me this is normal and this is actually the same way that the outside air was setup on the fireplace that I removed. I guess once the stove cools down I could just pull up the flexi pipe and see if it is plugged with anything. I did actually hear some critter noises around the stove last week but it was more in the ceiling than in the floor.

 

[rosencra38]

Should I really need the chimney cleaned out already since it was installed brand new just over two months ago?

 

[LLigetfa]

Just take out the dead raccoon.

 

[bbeals]

Just take out the dead raccoon.

After you remove said raccoon, make sure you put a cap with a screen over the pipe.

 

[Redox]

Reading between the lines here, but I think your chimney may be too short. Many single story homes, unless they have a tall attic suffer from the same problem. Chances are you have an almost flat roof, and even if the chimney is installed to code, it may be too short. I think you will need at least 15 feet or so to make this work. Try putting an extra section on the chimney and see if this helps. It can't hurt.

If you suspect a negative draft situation, just open a door to the outside. If the draft improves, then you've found your problem. If you suspect the OAK, disconnect it and see what happens.

Chris

 

[Corey]

... while looking things over further I noticed that I had smoke coming into the house from just below where the stove pipe goes through the ceiling. I checked outside and I had LOTS of white smoke coming out the top of the chimney. ...

This just doesn't sound right at all. "negative draft" or not, no smoke should ever come from the area where the pipe goes through the ceiling...EVER!! Secondly, if you had LOTS of white smoke coming out the top of the chimney, where is all that coming from? Lots of smoke coming out the top should mean lots of air moving in through the bottom...where is the only place it should be able to get in? ...that should only be through the stove. You're basically saying you have smoke coming out the stove and out the top of the pipe? Again - doesn't sound right.

Also, IMHO, two months of burning - even if it was wet pine - shouldn't be enough to clog up a flue to that extent. Plus, having coals in the stove that are hot enough to start a couple of added logs burning should be enough heat to have a good draft also.

It's extremely hard to tell remotely with out actually seeing the stove, but I'm guessing you would either have a loose connection where the stove pipe goes through the ceiling (Very dangerous - get checked out immediately), or possibly some critter has got in the flue and plugged it up (do you have a rain cap / screen?) or is there a possibility that some other appliance in the house is kicking on and pulling air out (such as a clothes dryer, bathroom / kitchen vent fan, forced air furnace, etc)

 

[begreen]

Two months of shoulder season burning damp wood can clog a screen. I agree there is a good chance the flue is too short too, given that this is a mobile home.

Go up there and pull the cap to see wazzup.

 

[rosencra38]

Two months of shoulder season burning damp wood can clog a screen. I agree there is a good chance the flue is too short too, given that this is a mobile home.

Go up there and pull the cap to see wazzup.

clog a screen? What screen are you speaking of, the outside air control?

Also, there is a rain cap/screen on the top of the chimney.

Question for yall. Why would I be experiencing problems with the flue length now after been burning for two months with no problems. At first I thought it might be the flue length combined with the lower temps we had when the problem first occured yesterday (low 30's) but tonight it has been in the 40's like it has been much of the earlier part of the season and still had the same problems. Either way, something is not right and I will be calling our dealer first thing tomorrow morning to see what is going on. Tomorrow after the stove has cooled down (I'm not throwing no more wood in until I figure this out) I will pull out the outside air control and see if something got in it or if it sucked up some insulation. I need to figure something out before this weekend when they are calling for high temps in the mid 30's.

 

[LLigetfa]

Next time it happens, crack a window open an inch and see if outside air rushes in. If it does, you have a makeup air problem.

My father had a 2-1/2 storey with a cookstove and another stove in the basement. He had a really bad case of stack effect. He would seal up anywhere cold air came in the basement but upstairs the warm air would leak out unnoticed. If I cracked open a basement window so much air would rush in that it would lift the casement window.

I realize a single story mobile home doesn't have "stack effect" but it can have an inbalance of pressure. When I started burning this fall, I noticed that I'd get a lot of smoke when I opened the stove. Turned out my HRV intake was clogged up with fluff. It was pulling air out but not letting the makeup air in. The stove has its own makeup air vent which would push the air (smoke) into the house.

 

[fossil]

Doesn't make any sense to me that the OAK duct should terminate until it's clear in the crawl space. If its open end is up inside the insulation and sealed by the plastic sheeting, how the heck is it s'posed to function? Seems to me, it oughta be clear of all that stuff and hanging in clear air and protected by a screen...or ducted all the way out to daylight through the skirt and screened. There should be an unrestricted and protected path for airflow all the way from the inlet of the OAK, through the stove, to the top of the chimney beneath the cap. Rick

 

[oconnor]

"I had smoke coming into the house from just below where the stove pipe goes through the ceiling."

Rosencra38

Slow down and re read the replies to your post. I agree with Begreen, fossil and cozy heat - you have something wrong with the setup. A chimney can certainly clog quickly, as well, you mention smoke coming from chimney joints - THAT IS BAD - a reversed flow will draw smoke out thru your stove, not thru chimney joints.

Also, as Fossil states - The Outside Air Kit (OAK) needs to draw air from the atmosphere outside the home, not from inside the plastic - it needs to run all the way outside the insulated envelope of the home. It should be screened over the end as well - I think your comment on critter noises made some folks think chimney - when I read it, I thought you were refering to the OAK.

As for a clogged screen - BeGreen is refering to some raincaps that have a screen on them - yours may not have a screen as part of the raincap. It does certainly sound to me like you have a blocked flue, and until you can prove that you don't, using the appliance is putting you and others at risk.

Check it out yourself, or call a pro - but have it checked.

 

[rosencra38]

"I had smoke coming into the house from just below where the stove pipe goes through the ceiling."

Rosencra38

Slow down and re read the replies to your post. I agree with Begreen, fossil and cozy heat - you have something wrong with the setup. A chimney can certainly clog quickly, as well, you mention smoke coming from chimney joints - THAT IS BAD - a reversed flow will draw smoke out thru your stove, not thru chimney joints.

Also, as Fossil states - The Outside Air Kit (OAK) needs to draw air from the atmosphere outside the home, not from inside the plastic - it needs to run all the way outside the insulated envelope of the home. It should be screened over the end as well - I think your comment on critter noises made some folks think chimney - when I read it, I thought you were refering to the OAK.

As for a clogged screen - BeGreen is refering to some raincaps that have a screen on them - yours may not have a screen as part of the raincap. It does certainly sound to me like you have a blocked flue, and until you can prove that you don't, using the appliance is putting you and others at risk.

Check it out yourself, or call a pro - but have it checked.

OK, I will work on re doing the OAK and will check the flue for any obstructions. I'm not that great when it comes to heights so I'll probably have to have someone come over and check that out for me. Thanks for all of your help. The fire we had started earlier this afternoon has dwindled down now and I don't plan on having a fire again until I figure this out.

Oh, and to answer your question, I do have a screen on my rain cap. The critter I heard sounded like it was in the ceiling joists and even hitting up against the stove pipe passthrough. I have no idea how it would've gotten in there in the first place...

 

[rosencra38]

Well, I stayed home from work today to try and get this figured out. I spoke with the dealer and he is convinced that my flue must be plugged and that is couldn't be anything with the OAK. If the OAK was plugged then the air in the house would rush into the stove not out of it when I open the door. Since the smoke is rushing out of the stove when I open the door he suspects that their must be a plug in the exhaust ie. flue... SO... I took the ceramic blanket and board thingy (can't remember the real name) out of the stove this afternoon. I placed a mirror on the bottom of the stove and shined a flashlight up the flue. I didn't see any obstructions within the pipe at all. I did notice that the bottom of the rain cap has one side that did not shine back at me but it was too high up to really tell what was there. I'm wondering if there is a critter that tried to get in and got stuck in the screen and died or maybe I have some leafs stuck??? I'm not really sure but if there is something there would this little bit be enough to plug things up?