White smoke from furnace exhaust (What does it indicates)

White smoke from furnace exhaust

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White smoke from furnace exhaust is not a bad sign as it is the normal color of smoke resulting from any byproduct. But some furnaces produce a very dense smoke like a cloud. Mainly depends on the heating equipment of your house.

The gray smoke could be an indication of a fuel problem. If your furnace uses oil as fuel, then there are chances that white color fumes will be produced.

Sometimes, it becomes difficult to determine whether the furnace is operating normally or needs some repairing. In this case, better to consult the technician to find the problem.

White smoke from furnace exhaust 

White smoke from furnace exhaust indicates inadequate combustion, which ultimately increases fuel consumption.

So, a high oxygen level is the main reason for the white smoke from exhaust furnace. In this case, excess air present in the furnace uses the heat energy produced in the furnace. 

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Although oxygen helps in combustion, the high oxygen level can be a problem. Moreover, white fumes are produced when water from your vents mixes with the fuel.

So, to avoid this, ensure the fuel is compatible and the air level is optimum.

What does the color of the smoke tell us?

Different furnace emits different color of smoke when there is an issue. We can predict the issue, which can help us to solve the problem.

  • White smoke from furnace exhaust indicates that the air level is high, which causes a disturbance in the normal working of the furnace.
  • Black smoke from furnace exhaust shows that the oxygen ratio is low compared to fuel. This causes incomplete combustion, which increases the fuel cost as most of the fuel will be left unburnt.
  • Grey smoke from furnace exhaust indicates that oxygen ratio and fuel consumption are optimum.

Why does the furnace emit smoke?

But what is the reason why your furnace emits more smoke than usual? Furnace usually emits smoke due to incomplete combustion.

That could be the air level is high or low. Another factor is to avoid the smoke. The furnace should be clean, and there should not be any dirt that can cause hindrance.

Moreover, if you burn anything using fuel, like oil and gas, then certain reactions occur, and smoke is the byproduct of these reactions.

Origin of white smoke.

White smoke is produced when combustion takes place in the chimneys. Normally, if the oxygen level is low, this smoke emits from the vents. In this case, fuel consumption is more as oxygen increases the consumption rate. 

Due to more fuel consumption, dense clouds like smoke will be produced. But this is not always the case. Sometimes, if the smoke is mixed with the water, it emits white condensed smoke.

Composition of white smoke.

The composition of white smoke from furnace exhaust can vary according to the fuel we use in the furnace.

The chemical composition of smoke consists of zinc chloride, hexachloroethane, aluminum, and zinc oxide. These are dangerous for humans if they inhale these materials.

Is white smoke dangerous?

Smoke inhalation is always dangerous for the human body, and affects the lungs critically and ultimately can be fatal for you.

Those chimneys or furnaces which emit white smoke are the major causes of acute lung cancer as it is dangerous for people, and the government should ban those industries. 

White smoke from furnace exhaust

Moreover, the continuous emission from the furnace is not ideal for the environment. According to research, furnace plays a major role in increasing pollution.

Air pollution is not only dangerous for humans, but other animals are also affected by this. We need to take precautionary measures to solve the problem.

What to do to avoid the white color smoke?

After finding the reason for the white color smoke, we should take some preventive measures to avoid this kind of problem. The main reason for the white smoke color is the air level. You should make sure that the oxygen level should be optimum. 

Because a high level of oxygen not only emits white fumes but also increases fuel consumption, which is constantly for the consumer.

Moreover, to avoid the white color fumes, you should check the chimney regularly and see if there are any problems like corrosion. 

Mostly, if your burner is old, then there is a chance that you will face this kind of problem. Dirt is another factor that can cause this problem.

So, to prevent this from happening, you should clean the vents regularly. Change the filters of the furnace regularly to avoid any issues. If you still cannot find the cause of white fumes, the best way is that consult an expert to solve your problem.

Precautions to take to avoid the problem.

  • Our earth has been facing a major pollution issue for a long time, and we are adding more pollution to our earth. Industries are the major cause of pollution; they continuously emit smoke containing harmful elements that can cause severe issues and prove fatal. Authorities need to take precautionary measures to solve the problem. 
  • They must ensure that all industries use filters that absorb harmful materials and ultimately protect the environment. Moreover, as time changes, we need to shift towards those power resources more suitable for the environment, like solar and wind energy.
  • People can use electric heaters to warm their houses instead of burning fuel in a furnace. The industries which emit harmful chemicals should be far away from the public. As in most countries, there is a certain level at which you can operate your industries, but if it increases from that level government take serious action.


White smoke from furnace exhaust indicates that you need to look at your chimney. White smoke density tells the user about the intensity of the problem.

Normally, most experts looking at the white smoke can tell that the air ratio is high in the furnace, and if you want to save fuel, you should keep the air at the optimum pressure.

Sometimes, when smoke mixes with the water, white color fumes will be produced.

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