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Thread: Whats that smell!
10-10-2007, 09:20 AM #1
Whats that smell!
I have a question pertaining to my own fireplace.
It is a masonry wood burning fireplace. I have a cozy grate insert installed and use the fireplace a lot.
Numerous times the family room where the fireplace is smells of soot. I have a top of chimney damper & the regular damper both closed. There are no ashes at the fire box or ash dump. It does not mater if it is raining/windy/calm it still smells sometimes.
I have the fireplace cleaned twice a year. I also used a product called anti creosoot as recommended by my chimney specialist as I have some glazing of creosote on the flue & smoke self.
My glass doors are older. Would replacing the doors help?
I have used a odor product but it just make the soot smell like vanilla or whatever the odor product is.
What causes the smell & why. What can I do to eliminate the smell.
10-10-2007, 09:44 AM #2
Re: Whats that smell!
I found the following on a Google search. It may help you out.
The Chimney Sweep Online Fireplace, Woodstove, Gas Stove and Barbecue Shop
Handouts - Smoke Smell In House From Fireplace Chimney
Smoke Smell In House When Fireplace Not Burning
"Q: We just bought a newer, tightly built house, and are grappling
with a rather strange problem with our fireplace. We might expect to
smell a little smoke when we have a fire going, but we don't. We
notice a strong smoke smell that comes from the fireplace when we're
NOT using it. We had the chimney cleaned and it didn't help (maybe our
Sweep didn't do a good job?). Do you have you any idea why our
fireplace smells so smokey, and what can we do about it?
A: Wood-burning fireplace chimneys smell smokey whether they've just
been swept or not, because no matter how thoroughly your Sweep brushes
the flue, he can't possibly remove every trace of soot and soaked-in
creosote. Even if he were able to sand-blast every microscopic remnant
of wood smoke deposits out of the flue, the very first wood fire would
deposit a fresh layer, and the pungeant, smokey odor would return. So
the real question isn't why your fireplace smells smokey: the question
is, why is the odor entering your house?"
"The biggest air pathway to the outside in most houses is the
fireplace chimney. A fireplace chimney can allow airflow in both
directions. When in use, a fireplace chimney is a powerful evacuating
force: the chimney updraft created by an open fireplace fire can move
hundreds of cubic feet of air per minute out of the house, in many
cases more air than the other pathways combined can supply! This is
why you don't smell the smokey odor when a fire is burning in the
fireplace: it is only when the fire dies down, and the updraft
diminishes to the point where evacuation from other sources overcomes
it, that the airflow in the fireplace flue reverses and the odor
So what other forces are evacuating air from the house, causing makeup
air to be pulled in through the fireplace chimney? At any given
moment, a combination of evacuating forces might be at work. Some are
mechanical, as is the case with exhaust fans and clothes dryers. Some
are from natural causes, as when the wind blowing against the house
creates positive pressure on the windward side and negative pressure
on the leeward side. Some are thermal, like the rising exhaust gases
in woodstove, furnace or water heater flues.
Another example of thermal evacuation is the so-called "stack effect".
Heated air has lower density than cold air, so the warm, buoyant air
in your house wants to rise through the roof, and the cold, heavy air
in your unused fireplace chimney wants to flow downward into the
house. If there are pathways in the upper stories or roof to allow the
rising room air to escape, the warm air will flow up and out of the
house and replacement air will flow down the chimney and in through
the fireplace. The stack effect is more pronounced in taller, leakier
houses and in houses with cold chimneys (like chimneys on outside
walls, exposed to outdoor temperatures for their entire length). Rainy
weather also accelerates the stack effect, because the wet air
entering the chimney is heavier than the dry air in the house.
Whatever the cause, whenever air travels to the outside of the house,
an equivalent amount of air attempts to enter somewhere to replace it.
If the chimney offers the path of least resistance for the makeup
airflow, the smokey smell of wood creosote will enter the house along
with the replacement air.
What can you do to stop your house from using the fireplace chimney
for makeup air? All you need to do is create enough resistance to the
flow of air down the chimney so that the other air pathways will
provide less resistance to nature's tendency to equalize air pressure
inside and outside the house. Here's some ideas:
1) Close the fireplace damper when not in use. This will sometimes do
the trick, although a damper alone may not provide sufficient flow
resistance, as most fireplace dampers are pretty leaky.
2) Add a good, tight-fitting glass firescreen. This will almost always
solve the problem, and will also inhibit the flow of heated air OUT of
the chimney when there's a fire going.
3) Consider a top-sealing damper. These mount at the top of the
chimney, and are opened and closed via a stainless steel cable running
down the inside of the flue.
4) Provide a source of outside combustion air to your other combustion
appliances. If your gas furnace, oil furnace, woodstove and water
heater aren't siphoning air out of the house, the demand for
replacement air will be reduced."
"Q: Your writeup about the smokey smell from a fireplace makes
complete sense. I've lived in our house for two years and have had the
chimney swept both years and have not been able to figure out why it
is always smoky for a week or two after a fire. Now I am sure it is
caused by the "stack effect". It is a very old 3 story house. I plan
on having the [top sealing damper] installed at the top of the chimney
10-10-2007, 09:50 AM #3
Re: Whats that smell!
I think by installing a new fireplace door might do the trick. The old one I have now does not seal very well & the clamps continuously come loose when I use the doors during the heating season.
10-10-2007, 10:18 AM #4
Re: Whats that smell!
Now that I looked at my doors & heater I see the problem. There is a 1 inch gap between the doors & brick. The cozy heater is installed to far in front of the fireplace.
I have a metal fire back installed at the back of the firebrick.
I guess I will take off the doors & try to adjust the heater so the door can be flush with the brick.
Can regular insulation be used if the paper is removed to temporarily seal the doors?