“When I turn on the stove in the morning, smoke enters my living room. But as soon as the stove is properly lit, everything works normally. What’s the reason for this? Is my stove broken or my chimney?”
Neither of them has to be bad.
One of the most common causes is a cold chimney in which insufficient draft has yet been generatedThe problem can occur especially when the oven is lit for the first time after a long break, or in autumn when it is not yet very cold outside.
Weather conditions, negative pressure in the house, or unsuitable fuel can also play a role.
However, the fact that smoke returns to the room is something that should not be regularly ignored.
1. Why does a cold chimney have poor draft?
The chimney draft is mainly caused by the density difference between the hot flue gases in the chimney and the cooler outside air.
If both the oven and the chimney are cold, this difference may be small.
In some cases, a column of cold air also forms in the chimney, which flows downwards.
After lighting the lighter, the flue gases may not be able to escape properly through the chimney and some of the smoke may re-enter the room.
Once the chimney has warmed up sufficiently and the correct draft is present, the problem can disappear.
However, this in itself does not prove that the exhaust system is technically sound.
2. Why does the oven smoke mainly in autumn or spring?
“My stove works perfectly in January, but I still have problems with it in October.”
There is a logical explanation for this.
In winter, the outside air is significantly colder, therefore a sufficiently heated chimney usually creates more favorable conditions for the chimney draft.
In autumn or spring, it can be almost as warm outside as inside.
The temperature difference is smaller, and the chimney can start up more slowly when lit.
Wind, the location of the chimney and the pressure conditions in the house can also play a role.
3. Can chimney draft influence the weather?
“Yesterday my oven was working perfectly, but today it’s foggy and rainy, and I can’t get it properly warm. And I haven’t changed anything at all.”
Yes, the weather can also affect the chimney draft.
Problems can occur particularly in foggy, rainy or unusually warm weather, when unfavorable temperature and pressure conditions coincide.
For example, during autumn fog it is usually quite warm outside, there is almost no wind, and the chimney can be cold after a while. The temperature difference may then not be sufficient to quickly create the necessary chimney draft.
Wind can also affect chimney draft. Depending on its direction, strength, and surrounding buildings, it can promote it, but sometimes it can also impede it.
Important: It is not true that a chimney automatically draws poorly in rain or fog. The decisive factor is the combination of weather conditions, chimney design, and operating conditions.
However, should the problems recur under certain weather conditions, a professional inspection of the chimney draft is recommended. It may turn out that the flue system only functions reliably under favorable conditions.
4. Is it the hood or the new, tightly fitting windows?
Yes, and sometimes, surprisingly, it is the main cause.
Imagine you have new, tightly sealed windows, the extractor hood is switched on, and you want to cause a flood.
The extractor hood vents the exhaust air from the house to the outside. If not enough fresh air is supplied, negative pressure can develop in the room.
This can disrupt the chimney draft and, under certain circumstances, cause a reversal of the flow direction in the exhaust gas path.
Other exhaust fans or incorrectly adjusted ventilation systems can also have a similar effect.
If you suspect this is the problem, turn off the exhaust system and have it checked to ensure that sufficient combustion air is being supplied.
Slightly opening the window can help in troubleshooting and identifying a problem with the vacuum cleaner. However, it is not a permanent substitute for a properly designed air supply..
5. Could the problem lie in the wood?
Naturally.
Wood that is too damp is harder to ignite and requires some of the heat to evaporate the water.
The exhaust gases can then have a lower temperature and the chimney heats up more slowly.
At the same time, increased amounts of smoke and unburned substances can be produced.
To light the oven, use a suitable lighter, dry, small wood shavings, and firewood recommended by the oven manufacturer.
Quickly and properly lighting the fire can help create suitable conditions for the chimney draft.
6. What happens if the chimney is blocked?
“The oven worked perfectly all last winter. Now, after the summer, it’s suddenly smoking.”
The cause could also be a limited exhaust gas flow rate.
There may be deposits, bird nests, or other blockages in the chimney.
The problem could also be due to a blocked vent or a mispositioned deflector in the oven.
If the oven behaves differently than before, do not try to remedy the lack of draft by adding more fuel.
Have the flue system checked by a chimney sweep, and if necessary, also the oven itself.
7. How do you properly light a stove so that it doesn’t smoke?
First, check that the oven and extractor fan are working properly.
Then follow the manufacturer’s instructions.
Many modern wood-burning stoves use top-down combustion:
- Place an appropriate amount of dry wood in the firebox.
- Add small wood shavings and a suitable firelighter.
- Adjust the combustion air supply according to the instructions.
- Light the lighter and operate the door exactly as described by the manufacturer.
- Let the fire burn and make further adjustments according to the instructions.
If you notice that the smoke is not escaping properly while lighting the fire, do not continue lighting the fire and do not try to fix the problem with a large fire.
If you have a recurring problem with a cold chimney, it is advisable to consult a chimney sweep who can assess the draft and recommend a safe course of action.
8. When should I call a chimney sweep?
Special caution is advised if:
- Each time the flame is lit, smoke regularly escapes into the room.
- The problem occurred suddenly, even though the stove had previously worked perfectly.
- Even after everything has burned down, the smoke returns.
- They suspect a blocked chimney or flue.
- The stove only works when the window is open.
- The problem worsens when the extractor hood or ventilation is switched on.
Repeated smoke emissions are not a normal operating characteristic that you have to accept.
Flue gases can contain carbon monoxide, which is neither visible nor odorless.
If smoke enters the living space, do not light a fire and follow the manufacturer’s safety instructions. If you suspect carbon monoxide poisoning or experience health problems, activate a carbon monoxide detector. Leave the building and call emergency services from a safe location: 112, 112, or 150.
What can you take away from this?
If the stove only smokes when lit and functions properly after lighting, the cause could be a cold chimney and insufficient initial draft.
However, similar symptoms can also be caused by weather conditions, negative pressure in the house, unsuitable fuel, or a problem with the exhaust system.
Just because the stove stops smoking after heating up doesn’t mean everything is okay.
If the problem occurs regularly, the cause should be investigated. A properly functioning oven should safely vent exhaust gases not only during normal heating operation, but also when lighting the fire.