PalletPaddy's Troubleshooter


 If your fireplace or stove smokes all the time

Ø  Problems with the design of the appliance:

§  Fireplace opening too large  - An ideal fireplace opening would not be more than ten times the cross sectional area of the chimney fluem often a three to four inch reduction in opening height will make a noticeable improvement in fireplace performance. The fireplace opening could be reduced by rebuilding the firebox to smaller dimensions.

§  Firebox too shallow - If the firebox is too shallow, the smoke may roll out near the top of the fireplace opening rather than entering the smoke chamber normally.  

§  Lintel too high - if the fireplace lintel (the steel bar supporting the top of the fireplace opening) is too high, it may allow smoke to roll out of the fireplace opening instead of going up the flue. 

§  Fireplace throat improper - if the fireplace throat (opening into the smoke chamber) is not constructed properly, severe smoking problems may result.  

§  Smoke chamber improper - the smoke chamber serves to funnel smoke from the fireplace opening into the flue.the smoke chamber can be too deep, too tall, or too wide. Smoke chambers should not be taller than the fireplace opening width, nor deeper than the fireplace opening. Smoke chamber walls should not incline more than 45 degrees from vertical.the walls of the smoke chamber should be smooth to reduce turbulence. 

Ø  Problems with the chimney

§  Chimney flue too small - if the chimney flue is too small, it will not allow smoke to exit the woodstove or fireplace fast enough and can lead to serious smoking problems.  As stated above, the fireplace and flue must be sized in a proper relationship

§  Flue too short - Short chimneys can often lead to smoking problems.  A short chimney is defined as one less than ten feet tall above the fireplace opening or woodstove flue outlet. 

§  Improper termination height – A chimney should terminate at least three feet above the point it passes through the roof so that any sparks exiting the chimney have time to cool before landing on the roof. It should also terminate at least two feet higher than any portion of the building within ten feet.  

Ø  Problems with air flow:

§  Airtight homes - Smoke cannot rise up the chimney any faster than air can be drawn into the home to replace it. If you suspect this problem, open a window near the fireplace the next time you have a fire.  If this cures the problem, consider installing an outside air supply so you don't have to leave a window open when having a fire in the fireplace.

§  Obstructions and blockages - The chimney could be obstructed with leaves and straw needles which fell into the chimney or were carried into the chimney by an animal or bird building a nest. Sudden blockages can occur in older, deteriorating chimneys if a portion of the interior chimney walls collapse.  

§  Damper closed - Make sure the fireplace damper is open!  This is an easy thing to forget if you don't have fires on a regular basis.

 If your fireplace or stove smokes sometimes

Ø  Problems with air supply to the fire

§  Competing vents /drafts - Anything which removes air from the home can cause smoking problems, especially in fireplaces. A competing vent could be the kitchen or bathroom exhaust vents or attic exhaust vents, especially if they are of the powered type.  Other devices that can cause problems include the clothes dryer, a central vacuum system, or a whole house fan.

§  Temperature - Draft can be defined as the difference between indoor and outdoor air temperature.  A fireplace that works well when it is very cold outside may smoke when the outdoor temperature approaches the indoor temperature. 

§  Wind induced downdrafts - Wind related smoking problems are the most common type of occasional smoking problem.  Wind induced downdrafts only occur when the wind is blowing and usually only affect a particular chimney when the wind is blowing from a certain direction. There are special caps which are designed to eliminate downdraft problems.  

§  Flow reversals - A flow reversal occurs when the pressure surrounding the woodstove or fireplace opening is lower than the pressure in the chimney. This can be caused by leaks or cracks in the upper portions of the home, if someone upstairs decided to open a window to let in fresh air, or when two chimneys are located close together. Make up air for the chimney in use can be drawn down the unused flue, pulling smoke from the flue in use.  The solution would be to close off the unused flue with a tight damper and install an outside air supply.

§  Backpuffing  ( jets of smoke emitted most commonly from a wood stove ) - It is caused by the ignition of a buildup of combustible gasses in the firebox.. Instead of burning steadily, combustible gasses build up in the firebox and periodically ignite in a small explosion, forcing smoke out of the stove through every available opening, including the air intakes. Likely causes are: shutting the air controls down too far, starving the fire of oxygen,  using super-dry wood, like pallets or kiln-dried wood blocks, which burn very rapidly, emitting too much combustible gas too quickly, or using firewood that is split very small, which also burns too rapidly, creating an excess of combustible gas in the firebox. Try opening the air control on the stove. If the smoking stops, it is very likely a backpuffing problem. If you have to open the air control to the point that the stove will overheat before the backpuffing stops, then reconsider your firewood supply

Ø  Other causes

§  Wood supply – Green wood or wet fuel can cause smoking problems.

§  Fire starting practices - Smoking problems can be caused by the way a fire is started and maintained.  Note if the problem occurs mainly when a certain member of the household makes the fire.

§  Cold chimney - exterior masonry chimneys collect moisture when not in use and are often much colder than the rest of your house when starting a fire. If fireplace gasses cool off before the smoke exits the chimney, a draft is going to be weak or non-existent. It is important to get a good draft and a strong fire going right away. If this is an issues you are having you will notice that starting fires gets easier the more often you use your chimney since it dries out throughout the season. A chimney cap is also useful during the warm season, to help prevent the problem.

  If you notice damage on your fireplace or stove

Ø  Stains on the brick above the fireplace opening – they are caused by smoke puffing out of the fireplace opening. Slight staining is a normal occurrence, but if it becomes a problem, see the smoke-related problems section here

See our Quick cleaning Guide for tips on how to get rid of brick stains.

Ø  Staining on the glass doors

§  The wood that you are using is too humid or has traces of rotting. Make sure you use good, seasoned  wood.

§  The fuel is positioned too close to the glass  -  It might be obstructing the air flow that is necessary to keep the glass clean  make sure to keep a minimum gap of 4" between the fuel and the glass.

§  The chimney draft is too weak.

§  The fuel gives away too much smoke - Wood logs can be very smoky, especially if not entirely dry, raw bituminous coal is very dirty indeed and many 'smokeless' fuels produce plenty enough smoke to severely stain stove windows. Try having the slider above the fire-door at least slightly open to pull extra air in above the fire, pushing dirty gases away from the window and helping them to ignite. If the appliance does not have such a control you can achieve the same effect by not quite shutting the fuelling door for no more than two or three minutes when you first light, or refuel, the stove.
The ceramic 'glass' commonly used for stove windows will develop very tiny cracks on its surface after a period of use, this is normal.

                  See our Quick clean Guide for tips on how to get rid of glass stains.

Ø  Cracked or broken stove glass 

Under normal use, the stove glass will not crack or break. Glass breakage can be caused by:

§  Severe over-firing of the stove.

§  Impact (hitting the glass with a log, or slamming the door into a protruding log).

§  Spilling cold liquids on hot glass.

§  Improper Fitting: If the frame is over-tightened or unevenly tightened, especially in doors that use clips, the glass could break from will usually crack from one clip to the other.

Ø  Damaged lining

§  Stoves get very, very hot inside - It is quite usual for ceramic or vermiculite firebox liners to crack or craze, often within a very short time. They need usually only be replaced when they have almost completely disintegrated. Help them last longer by using only very dry fuel.

Ø  Deterioration of surface finish

§  The siloxane paint usually used on stoves can withstand very high temperatures, but it is easily scratched and soon becomes dull, it is to be expected that it may need touching-up fairly regularly using a proper stove refurbishment paint. The vitreous enamel finish used for bright, shiny colours on many stoves is almost impossible to scratch, but it can chip. Vitreous enamel cannot be repainted or repaired.

     Ø  Build-up on your chimney walls - creosote

Creosote is a product of incomplete combustion: deposits of unburned, flammable tar vapors from wood smoke. Sometimes it is crusty or flaky in texture, but often sticky or hard, like slag. Creosote pose a serious fire hazard. Contrary to popular belief, creosote is not an inevitable product of solid fuel burning.  There are some basic causes:

§  Operating the stove at a too-low burn rate  -  Go outside and check the flue. If lots of smoke is billowing from the chimney, you are burning it too low. This is not at all energy efficient since creosote represents unburned fuel. You can upgrade to a new, epa-certified stove, which is designed to burn cleanly at a much lower burn rate.

§  Using the wrong type of fuel - Burning green, wet, or excessively dry wood, or fuel that your appliance is not designed for, can cause creosote buildup.

§  Oversized flue or improper connection - an oversized flue, an excessively-long stove pipe, or too many elbows in the stove pipe can prevent  the chimney from quickly drawing the combustion products to the outdoors.

§  Poor stove design -  Before the new HETAS approved stoves became available, "air- tight" wood stoves were considered the best type. Airflow into an air-tight stove can be closely controlled, in some cases to the point that the user can literally put out the fire by closing the air controls. In essence, the problem with air- tight stoves is that, while they offer the convenience of a long, low burn, they are not designed to burn the fuel efficiently during periods of low burn. Lots of fuel is wasted in the form of smoke, which condenses in the stove pipe and chimney as creosote. The solution is the same as for operating the stove at a too-low burn rate, above, although many older woodstove designs create a smoky burn no matter how you operate the stove.

 If you have problems with the burning process

Ø  Poor heat output

§  Worn/missing gaskets - Leaky stoves will often show a marked decrease in performance.

§  Chimney needs cleaning  -  If the venting system is getting blocked with soot and creosote, it will make a world of difference in terms of performance and safety.

§  Poor fuel supply - If the fuel you are burning is too green or wet, it will cause poor performance.

§  Changes in the house -  Adding insulation, replacement windows, or new caulking. If you have made the house much less "leaky" recently, you may have a problem of depressurization for a while.

§  Trying to heat too much space:  - Attempting to heat too large a room will result in excessive fuel consumption and damaging overheating. Check the instructions of the stove (a stove can heat a typical room of about 12m³ volume for each kw of output, so a 5kw model can heat up to (12 x 5) 63m³, a room of about 5m square. The actual size depends on the insulation and air-change ratio of the room.)

Ø  Fire suddenly goes out:  if the fire goes out with fuel still in the firebox, then this is probably because too little air has been reaching it, try leaving the air controls open a little more. Check that the door seals are sound and that there are no cracks or gaps anywhere in the flue. The fuel must be dry. 

Ø  Fuel doesn’t burn at all -  Have you got the right fuel? Hard fuels such as anthracite will simply not burn on ordinary open fires or on many types of closed stoves. Mineral fuels will not burn at all in flat-bed wood burning stoves with no grate or low-level air supply, such appliances burn wood very effectively, but they will even extinguish burning coal. Damp or 'green' wood fuel can be almost impossible to ignite.

 If you perceive strange or unpleasant  smells

Ø  Creosote build up - It has a very strong, acrid smell, generally much worse in wet weather or in the summertime. The first step is to have the chimney swept and stove pipe cleaned. You can read up on how to clean the chimney yourself, but be aware that creosote can penetrate the surface of the chimney lining. The best solution is to contact a professional chimney sweep.

If the chimney has been swept recently, consider the following possibilities:

Ø  No chimney cap - Dampness from rainwater in the chimney increases the odors emitted by soot deposits in the flue and ashes left in the stove. Solution: get a rain cap.

Ø  Soaking wet chimney - Just as a cap keeps water out of the inside of the chimney, a water repellent treatment keeps water from soaking into the outside of the chimney. And since a wet chimney smells more than a dry one, a water-repellent treatment might help. Ask your chimney professional about it.

Ø  Wind-driven downdraft in the chimney - Ideally, a chimney will draw air out of the house even when you are not using the stove, pulling odors with it. But if the odors seem to coincide with windy days, reduced draft - especially in warm weather - coupled with wind pressure may be the culprits.

Ø  Depressurized house - In some cases, air may be drawn into the house from the chimney, and odors along with it.

Ø  Burning stove paint odor - When your stove is new, or after you re-paint or polish it, there will be a period of burn-in, during which the stove will smoke and smell. Plan on burning the stove with the windows open for an hour or so after painting or polishing it. The procedure for "seasoning" new stoves is to burn several small fires before burning a long, hot fire. During these "seasoning" fires, most of the paint burn-in will take place. But the first few times you fire the stove high, you may get some residual burn-in odor. After five or six fires, it should stop.

Ø  Animals in the chimney - If you smell something coming from your chimney that you suspect is from animals (dead or alive), call your chimney professional. Don't try to remove animals from the chimney yourself. Once your chimney professional has removed the animals, consider installing a chimney cowl with a birdguard.

 If you hear odd noises: 

Ø  Whistling noise: stoves and chimneys sometimes make a slight noise as air is pulled though them,

Ø  Creaking noises: as metal parts expand and contract. These noises usually reduce over time.

Ø  Animals in the chimney – if you don’t have a chimney cap, you can expect to hear noises from birds, bats, or even the amplified buzzing of insects.