Hi gordonc,
It appears the smoke smell in the house when the fireplace isn't
burning might be caused by a variety of different reasons. I've found
suggestions on what to look for, how to fix it, and also some
suggestions on 'deodorants' that you might want to try. I've posted
my findings in no particular order, however the most comprehensive
information is at:
The Chimney Sweep Online Fireplace, Woodstove, Gas Stove and Barbecue Shop
http://www.chimneysweeponline.com/hosmell.htm
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?"
[edit]
"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
returns.
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."
[edit]
"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
like suggested."
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GardenWeb.com Fireplace Forum
http://ths.gardenweb.com/forums/load/firepl/msg0409424626458.html
"The chimney cap prevents rain water from running into the chimney. To
prevent the smoke odor from entering back into the fireplace and into
the house, you need to install something to seal off the air that is
inside the chimney. Most fireplaces have a damper directly above the
fireplace that does the trick. Some fireplaces have a damper at the
top of the chimney (under the cap) that is operated by a long chain
that runs down the inside of the chimney. The damper directly above
the fireplace works best to keep odors out.
Without a damper, you must burn a heck of a lot of wood!"
and:
"On damp, stinky-air days, when you're not burning a fire, try
lighting a candle (or 2 or 3) and placing them inside the fireplace
hearth. The rising air from the heat of the candles may be enough to
drive the smelly air out thru the top of the chimney. See if this
works for you."
and:
"I would suspect that your damper needs to be openned to assist in the
draught. Chimney dampers do not serve the purpose of keeping smoke
from coming down the chimney, they regulate the amount of waste gases
(heat) flowing up the chimney as well as somewhat providing a greater
or lesser amount of oxygen for the combustion of the wood by
draughting more or less fresh air from the room.
If you have a newer home you may have an airtight home, which is good
for reducing energy loss but not good to maintain a good draght for a
wood burning fireplace. Operating exhaust fans such as those found on
clothes dryers, bathroon fans and kitchen stove hoods suck much needed
oxygen from a dwelling and thus reduces the amount of much needed
combustion air to provide a good draught.
An inspection of the chimney flue should be done as well regularly to
ensure built up solids are not reducing the volumn of the flue, which
also may hinder a good draught.
If you can smell 'smoke' in a room that is not good and finding the
root cause of your smoky fireplace is a must."
and:
"The man who restored my fireplace, who seemed to know what he was
doing, said, that in NYC at least, the problem is the relationship of
the firebox to the chimney.
In particular, many older houses have chimneys that are too small. The
physics of this is better understood today. I have seen charts on the
web specifying maximum firebox sizes for different flue sizes.
Fortunately, our house was so old (1820) that the flue was bigger and
the firebox smaller and we should have no problem. Otherwise, they
install firebox inserts to create the right proportion between firebox
and flue.
Installing the insert would have cost 1500-2000 (probably cheaper
outside of NYC)."
============================================================================================
Fireplace & Stove Deodorant
http://northline.site.yahoo.net/5ru-85.html
"is designed to eliminate stale odors in chimney, stove and fireplace
when not in use, as in the humid summer months. Just pull up the wick
to activate. A bottle lasts 30 to 90 days. Deodorizes up to 1200 cubic
feet. 1oz bottle."
5RU-85 $7.89
============================================================================================
"Chimney Deodorant"
http://www.americanchimneysweeps.com/chimney_deodorant_product_descri.htm
A common problem with chimneys is, after you use them for a while,
sometimes they smell and cause a terrible odor in your home that can
last for days, even months.
Buy 3 and get one Free - C# 82001 - $21.80
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WASHINGTON POST
http://www.exstink.com/customer.html
"After a long winter?s use, our wood burning fireplace has a very bad
odor. I had the chimney cleaned and checked and cleaned out the
fireplace very carefully, but the odor stays. What can I do about
this? P. Forgarty
Fireplace odor is often caused by moisture, a dirty chimney or
unseasoned wood. Since you have already had the chimney cleaned and
checked, concentrate on the other two problems. A chimney cap will
help keep moisture out of the chimney. If you can get on your roof
safely, you can buy a cap at a home center and install it yourself.
The cost is about $40.00. You might also try a deodorizer. One call
ExSTINK (888-241-7874 or www.exstink.com) is guaranteed help fireplace
odor or your money is returned. A four pound container cost about
$18.00. Clean and vacuum the fireplace, then put some of the
deodorizer in a dish or bowl and place it in or near the fireplace.
The product absorbs the odor."
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http://real-estate-agents.com/tips/fireplace/smell.shtml
One idea is that the fireplace box might be too large for the flue to
vent all the smoke properly. Also the flue might need cleaning due to
a possible obstruction.
Don't burn anything but good dry hardwood. Never burn trash.
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Naperville Chimney Sweeps
http://www.napervillechimneysweeps.com/fqs.html
Q: How can I stop my fireplace from smelling?
A: Here's a list of things to try:
1) Have your chimney cleaned. This will help a great deal, but it may
not eliminate the smell entirely.
2) Check for a flue cap, if you don't have one, install one. It will
keep the rain out. This will cut down on that "musty" smell. (It will
also prevent water damage to the firebox, and it keeps birds & animals
out too!)
3) Use "Odor Stop". Odor Stop is a fabric bag containing neutralizers
which is placed in the fireplace to absob odors. It is available
through us. (It really works. I put one in my fireplace and haven't
smelled it since!)
4) Deodorants, sprays, candles and other commercially available
products can also help to cover up and absorb the odor.
5) Open the damper and light the log lighter. This will help dry out
the flue and reverse the draft temporarily.
6) Open a window about an inch. This works especially well if the
problem is caused by attic fans and air conditioners."
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Google Search:
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Best regards,
tlspiegel |
