Help - Smoke Smell In Basement

[sn8k007]

We have a wood burning fireplace on the first floor, last night when we burned it there was a heavy smoke smell (but no smoke we could see) in the basement room directly below the fireplace. Originally I thought the furnance was creating some pressure and pulling in smoke from the ash trap, but it's sealed tight with gorilla tape (too much macgyver as a kid). There are no other spots for smoke smell to enter this room.

Any ideas?

Details

1. Wood burning fireplace with standard screen doors
   
2. Fireplace has a fresh air intake at the front which was open
   
3. Their is an ash clean out trap door (easily tripped open) at the back of the fireplace which empties below. I gorilla taped the clean out access door shut last season when we had a lot of smoke in the same room, thinking it was coming from the ash clean out. The clean out is in the room where we smelled the smoke.
   
4. The room with the smoke smell is semi finished and contains the furnance and air handler as well as tankless hot water heater. The furnance has an external intake that is a few feet off the ground towards the back of the house and the tankless has a similar intake (neither are anywhere near the chimeny which is 40 feet above)
   
5. Chimney is attached to the outside of the house

 

[Sodbuster]

We have a wood burning fireplace on the first floor, last night when we burned it there was a heavy smoke smell (but no smoke we could see) in the basement room directly below the fireplace. Originally I thought the furnance was creating some pressure and pulling in smoke from the ash trap, but it's sealed tight with gorilla tape (too much macgyver as a kid). There are no other spots for smoke smell to enter this room.

Any ideas?

Details

1. Wood burning fireplace with standard screen doors
   
2. Fireplace has a fresh air intake at the front which was open
   
3. Their is an ash clean out trap door (easily tripped open) at the back of the fireplace which empties below. I gorilla taped the clean out access door shut last season when we had a lot of smoke in the same room, thinking it was coming from the ash clean out. The clean out is in the room where we smelled the smoke.
   
4. The room with the smoke smell is semi finished and contains the furnance and air handler as well as tankless hot water heater. The furnance has an external intake that is a few feet off the ground towards the back of the house and the tankless has a similar intake (neither are anywhere near the chimeny which is 40 feet above)
   
5. Chimney is attached to the outside of the house

Not sure where you are located, but in cool damp weather smoke can hang and get drawn in by other appliances. I had this exact same problem and the smoke smell, (never saw any smoke), it entered the same room in the basement with the water heater and furnace. Somehow a small amount of smoke was entering the room. Take a look for any gaps where your furnace and hot water heater vent. My standard vent water heater vented up it's own pipe, up the chimney. I had that lined since it just stubbed into the second tile, but they didn't seal the top properly. We also had two clean out doors in for the ash dump in that room, once I siliconed them shut, and siliconed the chimney cap for the water heated, I had no more problems.

 

[sn8k007]

Update here: I sealed up the ash clean out door in the furnace room with silicon caulk and it seems to have fixed the issue. This would mean that smoke was coming down the ash cleanout door and seeping/being sucked out the door in the furnace room.
Plan is to seal up the ash clean out trap door since we don't use it.

 

[begreen]

The silicone can be considered a semi-permanent fix. I would leave it at that.

Is this a one flue chimney or is there another flue that goes to the basement?