Chimney Odors – When the Fire is Out!
Chimney Odors when the fire is out! Call 301 chimney for a professional analysis, now!
By 301Chimney CEO, Dave Myers
There are several causes for the various types of chimney odors. This particular article will discuss smoke odors within the house when the fireplace is not in use. In later articles I will discuss smoke and smell while the fireplace is in use, dead animal smells, and other odor related topics.
First, once in a while a homeowner reports a smokey smell on rare occasions during the summer when the fireplace is not in use. I have experienced that in my house. It is not very often and not overpowering, so I don’t concern myself with it too much and haven’t taken any action.
For those who find it more bothersome or those with a more pronounced smell or with a more frequently occurring problem, I pose several questions to help me diagnose the problem.
Is it worse after it rains, on windy days, or on hot humid days? Does the central air conditioning or heat trigger the odor? Is the fireplace in the basement? What level is it on? (The pressure is lower in lower levels of a house making lower level fireplaces more likely to draw air into the room through the chimney when it is not being used.)
How long has the problem been happening? Have you had replacement windows put in recently? Do you have or use a whole house fan? Does opening a door or cracking a window help?
I know that’s a lot of questions, but information is critical. No service tech can stay at your house for several days to experience all of these issues. If you can’t answer most of these questions, you may not be able to have your issue diagnosed.
In any case I invariably recommend a rain cap if there is not one already. Unlike most chimney techs I do not recommend a top sealing damper unless one has had the top of the fireplace flue sealed off with plastic and tape and found that this stopped or reduced the odor.
Top damper’s success rate for these odors is fairly low. But if rain is the culprit they work better than rain caps at keeping rain out and if the plastic helps, so will the top damper. Of course if your damper is broken or you want to increased heating fuel efficiency, I’d recommend one for those reasons. But, just don’t get your hopes too high on the odor issue unless you have tried the plastic.
If your chimney has water staining inside the fireplace of chimney and/or rain stirs up the odor in your house, checking and repairing the exterior masonry and applying water repellent would be a good idea.
If cracking doors between levels of the house helps it is an air circulation/pressure issue. Leave the door cracked or put louvers in it or put a ventilation grill in the ceiling between the 2 floors. The open areas of your louvers or grill must equal the area of the opening of the door when cracked.
If you have to open an exterior door, and your heat is on when the smell starts, you will need a make up air supply for your heating plant. If it is summer and your ac is on, no air should be going out your chimney so you will either need to try to balance the air between different areas of your house or have outside air brought in to your return air vents. This I don’t like too much as it will put warm air into your AC decreasing efficiency.
A poorly sealed/insulated house will leak air out the upper levels and sometimes draw air in a chimney. Sometimes it is difficult to find exactly which issue is the source, but again information, testing and monitoring results may help you with your quest. If you suspect the heating or AC appliances are involved, an HVAC expert should be consulted
Whole house fans will always cause negative pressure and will draw air down your chimney. A good damper will help reduce this a lot, but some leakage may still occur because the fans are very powerful.
Chimney exhaust fans will always eliminate odors, but they are very costly. Maybe $2,000.00 installed (more or less, depending on size) They can be used with a bottom damper closed so little air loss occurs and little electricity is used. They don’t use a lot anyway. But, they do have to either be put on every time the odors occurs or run constantly, if the odor is an every day thing.
Though they usually last for years, chimney fires will destroy exhaust fans. Once installed they must be on to build a fire and they have to be turned up fairly high as well. This creates a much more audible wirring of air much like a window fan. Everything has it’s upside and downside.
As for smells shortly after the fire goes out and lasting for hours or days, all of the same tests and many of the same questions are relevant. I have never been able to fully explain, or have explained to me, why 2 chimneys, both having down drafts and both looking similar, can have one smell and the other not.
Sometimes it’s the 3rd degree or shiny creosote in one and not the other, but sometimes they look identical and both people seem to be burning seasoned hardwood. A few people have experienced this from the FIRST FIRE in a new home! Ive witnessed this in person, myself. In 2 cases the smell persisted for several days.
Airtight glass d0ors ($2,000 – $3,000) help, but since they are not necessarily 100% air tight it can still smell a fair amount. Top dampers seemed to lock the smell into the house. On of those people bought an exhaust fan and the problem immediately ceased. Of course, it will every time, but it has the down side of noise when the fire is going and it is very expensive.
In review, see if rain or wind is the culprit. Caps are available to divert either one. Try cracking doors and windows, etc. Take notes. Have your masonry (brick or stone) inspected and repaired if needed. Consider water repellent, (it also acts as a masonry preservative.) An exhaust fan will always work but is expensive and must be turned up until it’s audible while having a fire because the fan blades and weather shield restrict the smoke unless the fan is running strong.
By the way, chimney deodorants are available and may help in very, very mild cases.
Dave Myers
Founder and CEO
301Chimney
Call 301 chimney for a professional anaysis now
PS: If your fireplace is below ground, there is the possibility that water could be seeping into the chimney below ground causing odors to kick up. If this is suspected a water proofing expert should be consulted.
