Persistent Draft Problem

MrsABF

New Member
Aug 14, 2017
2
Texas
We bought a 20-year-old home with a brick fireplace a few months ago. The fireplace is in the center of the house, brick, and has a terra cotta liner. We didn't notice any fireplace odors when we looked at the house (it was snowing--no AC turned on).
Fast forward to moving in in June, and the entire living room smelled like a BBQ pit. We called a certified chimney sweep who thoroughly cleaned the chimney and firebox, and inspected the chimney with a camera. He said it was filthy--an inch and a half of creosote had built up. He also placed new glass doors in the opening.
The next day, the smell came back. I read several threads on here about the AC pulling air from the chimney. Sweep temporarily capped the top of the chimney with sheet metal and caulk because we don't plan on using it, but future owners may. That should prevent air being pulled in.
We still had the smell. My husband put in foam rubber below the closed flue, at the recommendation of the chimney sweep.
Guess what! Still stinks. HVAC company installed outdoor air vent from roof to HVAC unit.
Still have the smell in the afternoons. Chimney sweep came back and put a fan on the top of the chimney for 3 days to pull air out. Finally, no smell!
So, he tells us our options are $3k plus fan installed on top of chimney (plus electrician's fee), chemical treatments to chimney at $1100 a piece (it may take 3 times) to remove baked in creosote, or sheet metal and caulk the opening of the fireplace and hide with screen to completely seal off fireplace. I really like the doors we had put on, but the way it mounts would mean losing them if we go the sheet metal route. This has already cost over $1k and we really, REALLY don't want to spend $3k+ on a fan. So...any other ideas?
 

Doc C

Minister of Fire
Jul 26, 2017
673
Bonner County Idaho
In summer time the stack affect can be reversed and air can be drawn down the chimney into the house. Even though you cap it off there is still creoste in the chimney which is essentially inside your house because the chimney is internal to your house.

I personally think it's more common in a 2 story house. Not sure if yours is a 2 story or not.

Some basic things would be to try opening windows in a deliberate manner such as try to open one near the stove for a day. If that doesn't work then open one on the second floor if you have one.

What you are trying to do is to get the air pressure to change in the house.

Unfortunately I have a feeling that none of these things will work in your situation.

My guess is that you have the same thing going on that I do in my house.

I have not found a permanent solution. Every spring I cap off my chimney, clean my chimney real good including my clean out as I have a wood stove on a masonry chimney, and I put BAN odor eliminator mixed with water in a 2 gallon pump spray bottle and spray down the chimney with a light spray. I try not to get it to wet. Just a light mist.

It seems to last a few weeks and I have to do it again.

I will be following this because I'm interested in other ideas as well.
 

double-d

Feeling the Heat
Feb 8, 2011
322
Northern Michigan - Mio
All wood burning chimneys have creosote you can't prevent that, but keep from having a downdraft would be the best solution.
I had the same issue when we moved in to our house (Ranch) but I ultimately ended up installing a Top Lock Damper and no longer have an issue. I also have Glass Doors so that also helps.
If you don't have one get a cap on the chimney, it will help keep water out and helps keeps the flue dry.
Temporary solutions can be lighting a large candle and set it or them in the fireplace creating a positive draft. By adding a little heat, it will reverse that draft, forcing air and those odors up the chimney and out.
You could be smelling lingering effects of smoke or ash dust, Wipe down everything with diluted ammonia or white distilled vinegar, and scrub down the sides and bottom of the fireplace.
Open windows when you can, and reduce the amount of time the kitchen and bathroom fan runs and using clothes dryers.
 

MrsABF

New Member
Aug 14, 2017
2
Texas
Thanks for the replies.

Doc C, it's a one-story house. Because we live in Texas, I really don't want to leave the windows open all day. This is frustrating because it's a nice house in a nice neighborhood, but it seems to have this problem that can't be fixed without a fan running all the time?

Double D, the top is capped with sheet metal and caulk--air tight. The bottom is plugged with foam rubber. We have glass doors. We "shouldn't" be having this problem...but we do.
 

Doc C

Minister of Fire
Jul 26, 2017
673
Bonner County Idaho
Thanks for the replies.

Doc C, it's a one-story house. Because we live in Texas, I really don't want to leave the windows open all day. This is frustrating because it's a nice house in a nice neighborhood, but it seems to have this problem that can't be fixed without a fan running all the time?

Double D, the top is capped with sheet metal and caulk--air tight. The bottom is plugged with foam rubber. We have glass doors. We "shouldn't" be having this problem...but we do.
Unfortunately it's a common problem with masonry chimneys and it's made worse with the air flow being worse in the summer.

In your case the airflow should not matter because you have stopped that issue by making the chimney air tight. As long as it is actually air tight.

An option that most people do not want to do but I have actually considered is tearing down my chimney. Not easy, not cheap to hire out but it is a solution.

I can say almost for a fact that this will only be a problem in the summer time. Not that is much comfort. I am dealing with this in my house and it drives me insane.

I would be very hesitant about having chemical treatments done. I have 2 stoves in my house. The stove with the smooth liner never smells of creosote but the one with the rough liner smells horrible.

I just can't see how them cleaning the chimney with a poultice is going to get rid of the smell. It might help somewhat but it seems that there will always be some creosote stuck in the crevices. I may be wrong as I have never seen it done it just doesn't seem like it would work 100%.
 

double-d

Feeling the Heat
Feb 8, 2011
322
Northern Michigan - Mio
Whether it's negative pressure in the house, or reverse stack effect, or whatever you call it, you are getting a downdraft through the chimney, and that is why you are getting the smell. Getting rid of the downdraft, even the worst smelling chimney will not be noticed in the house.
The smell is due to creosote deposits in the chimney, a natural byproduct of wood burning. The odor is usually worse in the summer when the humidity is high and the air conditioner is turned on. A good cleaning will help but usually won't solve the problem completely. There are commercial chimney deodorants that work pretty well, and many people have good results with baking soda or even kitty litter set in the fireplace.
The real problem is the air being drawn down the chimney, a symptom of overall pressure problems in the house. Some make-up air should be introduced somewhere else in the house (opened window, patio door...). A tight sealing, top mounted damper will also reduce this air flow coming down the chimney as mentioned, your sealed plate on top is fine, just not practical.

This also could help if you are in an area that is fairly windy, is a Wind Directional chimney cap or Vacu-Stack style cap. They are designed so when the wind blows across the top of the chimney, it will create a positive draft, and pull air out of the chimney.
 

Doc C

Minister of Fire
Jul 26, 2017
673
Bonner County Idaho
Whether it's negative pressure in the house, or reverse stack effect, or whatever you call it, you are getting a downdraft through the chimney, and that is why you are getting the smell. Getting rid of the downdraft, even the worst smelling chimney will not be noticed in the house.
The smell is due to creosote deposits in the chimney, a natural byproduct of wood burning. The odor is usually worse in the summer when the humidity is high and the air conditioner is turned on. A good cleaning will help but usually won't solve the problem completely. There are commercial chimney deodorants that work pretty well, and many people have good results with baking soda or even kitty litter set in the fireplace.
The real problem is the air being drawn down the chimney, a symptom of overall pressure problems in the house. Some make-up air should be introduced somewhere else in the house (opened window, patio door...). A tight sealing, top mounted damper will also reduce this air flow coming down the chimney as mentioned, your sealed plate on top is fine, just not practical.

This also could help if you are in an area that is fairly windy, is a Wind Directional chimney cap or Vacu-Stack style cap. They are designed so when the wind blows across the top of the chimney, it will create a positive draft, and pull air out of the chimney.
They have completely air sealed the chimney. It's not possible to have air coming down the chimney in their case. Assuming they truly are completely air sealed.

Also I have personally air sealed my chimney and I still have the smell. 100% air tight from the top.

I think there is more at play in some of these situations then we have realized over the years.
 
Last edited:

double-d

Feeling the Heat
Feb 8, 2011
322
Northern Michigan - Mio
After 20 years I would bet big money that there are voids from missing mortar and cracks in the clay tiles.These voids and cracks, could be what is allowing the smell to enter the house.
These problems need to be addressed, probably by installing a Stainless liner, and insulating the liner. Breaking out the clay tiles is usually required when lining a fireplace flue, if there is minimal room. You have now removed the creosote and made access for a stainless liner and for the insulation. The stainless liner will be sealed on the bottom so smoke and gases cannot go to the outside of the liner. Now no remaining creosote smell can enter the house and you chimney is now back to code.
There are also many options if you would rather install an Insert or Stove instead of using the fireplace.
 

Doc C

Minister of Fire
Jul 26, 2017
673
Bonner County Idaho
After 20 years I would bet big money that there are voids from missing mortar and cracks in the clay tiles.These voids and cracks, could be what is allowing the smell to enter the house.
These problems need to be addressed, probably by installing a Stainless liner, and insulating the liner. Breaking out the clay tiles is usually required when lining a fireplace flue, if there is minimal room. You have now removed the creosote and made access for a stainless liner and for the insulation. The stainless liner will be sealed on the bottom so smoke and gases cannot go to the outside of the liner. Now no remaining creosote smell can enter the house and you chimney is now back to code.
There are also many options if you would rather install an Insert or Stove instead of using the fireplace.
I was wondering about that. If there is voids in the chimney allowing air in but it would seem that it would of started a fire by now in the house if that was the case? In my case I know there has been small chimney fires that didn't extend to the house so it made me dismiss that theory but maybe I need to relook at that.