Too much wood in firebox when there is a reverse draft?

Hi, everyone! My stove has a frequent reverse-draft problem. (Tight house with a 15-foot liner in an outside brick chimney.) In most cases, opening a nearby window for a few minutes takes care of the problem while the fire starts. At other times, a lot of smoke fills the room regardless of how much (or how little) I open the window. Can the amount of wood in the firebox be making the problem worse?

I can easily tell when I have a reverse draft. I feel the wind coming out of the stove as I stack the wood inside the firebox. I use plenty of dry kindling, and I usually start with one or two kiln-dried logs -- so, everything is very dry. The hope is that the wood will catch quickly and correct the draft in a very short time. When I have a noticeable reverse draft, would it be better to load up the firebox with kindling and firewood, or is it better to keep the big logs out at the beginning? I am wondering if too much wood is blocking airflow. Please let me know what you think. Thanks!

 

Ever tried using a hair dryer aimed toward the flue pipe in the stove to prewarm the flue?

 

I find more small pieces of best-in-class pine get the fire going faster in the morning with a much shorter duration of smoke.
With both N/S stoves I tend to put a big chunk to each side and have the starter fire in the middle . I come back a little later, turn the air down and add another big split or two where the starter fire is now mostly 'coals'.
Only faster way I can think of is a hair dryer/heat gun. Having never tried it can't say how well it works. It should.

 

Just how high is your chimney and where is it in location to the nearest point of the roof measured from the exit point of the chimney?

 

Here is a diagram of the clearances your chimney should meet. Not meeting these clearances can also affect the draft.

 

Get a hand held propane torch aim towards the chimney from inside stove to pre heat

 

Not sure but it sounds like you don't have enough clearance above the roof.

 

Around here it depends on which way the wind is blowing. Sometimes I have to open a widow at the north facing side and sometimes it is the south facing side.
If I open the wrong window I have seen it suck the fire right out of the stove and start smoking up the house. Need less to say I have learned my lesson.

 

Reverse drafts are common on some setups. Never happen on others.
I have a wood furnace in the basement. Had occasional problems with reverse drafts when cold. Woodstove upstairs never had any significant issue I could see.

Here’s my theory on the basement. Cold air is sinking in the flue. That’s natural. To have a serious effect I theorized it had to be traveling rather fast with good volume. So where is it going after leaving the stove? I guessed the next lowest and open point was down the drains in the floor. Put some small scraps of plywood over those drains and the problem lessened.
your on the first floor. Make sure the door to your basement is closed. If you have a warm air furnace it may be circulating down through the floors registers when not running. Not much you can do about that.

Bottom line, get a can of Mapp gas and fire that up inside the stove for a minute or two until you reverse the flow. Lights kindling good too. Auto start head is great. No looking for lighters or matches. Just don’t leave it close to the stove please.

 

My basement wood furnace has an external chimney and does reverse during startup. The steps I take to prevent a reverse pushing smoke into the house:

1. Open the window nearest the furnace first before opening the furnace door. If I open the furnace door first, the down draft gets a lot of momentum and is difficult to reverse.

2. I put in one medium piece of DRY split wood, usually half a round, on one side of the firebox and a pile of paper next to the open face of the split wood.

3. The paper is layered with fast burning crumpled newspaper on top and heavier paper at the bottom (crumpled grocery bags). All my paper is pre-crumpled and just added to the firebox. Crumpling paper with the window open lets in a lot of cold air.

4. Three pieces of 1" +/- dry kindling go on top of the newspaper.

5. I light the top newspaper layer and pinch the door to provide combustion air while directing the newspaper burning heat up the stack.

6. I close the window after chimney draft is established.

7. Add larger wood on top of kindling, 2" +/-, after about half the paper is burned.

8. I do not completely close up the furnace until my stack is approaching 250 deg on an external spring dial flue gauge.

If it is cold outside, I work fast with that window open.

External chimney's can become a column of cold air and cold air is heavier than warm. The heavier cold chimney air just falls in to the warm house air which is less dense. Opening the window "pressurizes" the house with a dump of cold heavy air from another source. Internal chimney's are kept warmer by the house surrounding the chimney and so the air is less dense (warmer) and less prone to fall into the house.

During very cold sub-zero weather, I will open the window, add the split, add the newspaper and immediately light the newspaper to create a quick burst of hot flue gas to go up the chimney. Then, I close the window and add more paper and the kindling.

 

My cleanout is inside. Thats how i do it.
Had to do it Saturday night after letting the stove go cold for repairs.

Ive used lots of news papers stuffed in the firebox around the wood to get a big push of heat also.

 

We used to have a Jotul 3CB and had the same issue from our basement installation. Not so much with the Fireview and a SS liner. I had to open a window nearby and warm up the pipe above the stove with a torch before lighting the fire. Even then it could be a challenge. Heating that cold flue somehow is your best answer. Cold air seeks to replace warmer air. When your chimney is cold it’s bringing cold outside air in to replace your warm house air. Heating the stove pipe connecting to the chimney should reverse the flow. A rolled newspaper can be lit and held in the flue opening inside the stove also if you can reach it. Good luck!

 

Its actually warm air leakage at the upper parts of the house that often causes issues like this with pulling cold air in through these basement flues...its called stack effect.
Stack effect - Wikipedia

 

True. Air can be displaced anywhere. But in that scenario to create a large downdraft you would require a large leak. Small downdrafts can usually be overcome with normal paper and kindling. Huge ones need a place to displace the air. Either your ankles will be freezing or it’s going somewhere else LOL

 

Heavier cold air falling into a house will cool the house air, cooler air being more dense, the house air will "shrink" as a result and so make room for more cold air which will cool/shrink the house air more, creating a steady cascade of cold air... even in an air-tight house.

I have had cold air pouring in an open window next to the furnace and the chimney down flowing which combined is a lot of air. Where is it going? Warm air shrinkage.

Why open the window before opening the firebox? To prevent a chimney down flow frequently and based on experience, an open window makes reversing a down flow easier. Obviously, there are many ways to create a burst of heat to reverse a down flow and my process is just my favorite.

If a chimney is down flowing and coals are in the firebox then it could put carbon monoxide into a house. I do not "park" my furnace with coals to avoid down flowing and so carbon monoxide, i.e. I scatter my coals and burn them off quickly rather than "park" coals and then restart the furnace later with paper/kindling. I try to feed wood only as needed to either heat the house or keep my chimney warm enough (by the dial gauge on the flue) to not back flow.

 

^^^^^This. My sister had a problem with smelling the wood stove, bad, whenever the wind blew from the NNE. I found cold air was coming in down the oil boiler chimney any time the boiler wasn't firing. For that chimney to reverse the air had to be going out somewhere and the biggest culprit was the attic foldaway stairs in the son's bedroom that always complained his room was cold. It was sealed shut with box tape at one time but the tape was mostly no longer sealing. Put a insulating box over the opening. No more wood stove smoke in the house. Their heating bill went down as did the cold room complaints. Surprise, surprise. Her ceiling cans at least has insulation over them but they could still use wind sealing.

 

Yep! You beat me to it. Works every time.