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Bad Draw: What it is, and How to Improve Chimney Draw

A bad draw is often caused by a faulty connector or flue. Check that all existing valves in the connecting pipe are in the correct (open) position.

When smoke comes back into the room, this can be because the flue is not yet warmed up. The chimney only has a good draw if the smoke is warmer than the outside air. Heat up the flue by rolling up a piece of newspaper into a torch and keep it in the flue until the smoke is going in the right direction. Chimneys that run along the outside of the house, particularly, require some preheating.

Improve the draw of a chimney

Factors Influencing The Draw

The Build Of The Flue

- The diameter of the chimney must not be smaller than the diameter of the outlet of the stove.

- A higher chimney means a better draft. If the draft is not sufficient sometimes, a higher chimney is sufficient to improve the draw.

- A chimney with a round insert pipe normally gives a better draft than a square.

- The use of elbows in the pipe reduces the pull. If there are bends to be used, 2 x 45 ° is preferred over 1 x 90 °.

The Supply Of Combustion Air Is Of Essential Importance For The Tensile

An open fireplace needs about 300 m3 of air per hour, and a "closed" fireplace needs approximately 30 m3 per hour.

A kitchen fan or hood sucks much more air than a chimney. This can lead to a kickback. In other words, the kitchen hood draws air into the room coming from the chimney, thereby drawing smoke into the room.

Opening a window should solve this problem immediately.

Influence Of The Wind

The draw can be disrupted by:

- high trees

- cliffs

- high buildings

This problem can usually be solved by making the chimney higher. In extreme cases, an exhaust fan can be installed. A draft regulator can stabilize the draft of the chimney.

Reduction Of Draw

At high temperatures, the fireplace provides a strong pull. The best results are achieved when the height and diameter of the chimney are aligned with the device in use. If the pull is too strong, the heat can quickly be sucked into the chimney. A draft that is too strong can be adjusted with valves, draft regulators (insert pipe or chimney), or restrictors. The use of multiple bends in the flue pipe reduces the pull.

Potential Results of a Bad Draw

Why is a bad chimney draw a problem? There are many potential effects if your chimney isn't drawing properly, including the following:

  • Smoke Backflow - In the case of a bad draw, smoke may sometimes flow back into the room rather than out the chimney. Naturally, this is undesirable for a range of different reasons, including safety concerns.

  • Incomplete Combustion - A bad draw may lead to the stove not burning the fuel as completely as it otherwise would. 

  • Reduced Heating Efficiency - Because of the incomplete combustion, the stove may not heat as efficiently as it would when functioning correctly. 

  • Creosote Buildup - Creosote is a toxic byproduct resulting from combustion. Under these conditions, it may build up in the chimney flue or, worse still, start building up in the room itself.

  • Carbon Monoxide Exposure - Carbon monoxide is an odourless and colourless gas that can be fatal. If a chimney isn't drawing properly, carbon monoxide can easily build up within a room.

  • Damage to the Appliance - A bad draw can even result in damage to your wood stove. Consistent problems with airflow can damage various system parts, leading to a broken appliance.

  • Excessive Creosote Odors - A bad draw can lead to a buildup of undesirable scents.

  • Condensation Issues - When the chimney draw isn't as good as it should be, there may be issues with condensation buildup.

  • Environmental Impact - When there's a problem with the chimney's draw, the lack of proper burning and several other aspects leads to a greater environmental impact. For instance, when the wood isn't burning properly, it creates more greenhouse gases than it would when working properly.

  • Increased Fuel Consumption - Naturally, when your wood stove isn't burning fuel properly, you need to use more fuel to achieve similar results. This can increase the cost of running the applications significantly.

How To Improve Chimney Draw

Once you've identified that you have problems with your chimney draw, it's time to look towards remedying the problem. Here are several ways you can improve the bad draw from your chimney.

  1. Ensure Proper Sizing - Confirm that the chimney's diameter isn't smaller than the stove's output.

  2. Check for Obstruction - Ensure that the stovepipe and chimney are free of obstructions.

  3. Maintain Cleanliness - Ensure that you have scheduled regular cleanings for your chimney to prevent dirt buildup.

  4. Use Dry, Seasoned Woods - Only burn dry, seasoned woods to ensure that you don't have buildups of smoke. 

  5. Preheat the Flue - Before starting a fire, roll a piece of newspaper or cardboard into a torch and burn it. Hold it up to preheat the flue, which can get the desired airflow started.

  6. Optimize Chimney Height - Taller chimneys lead to better draw. If at all possible, extend the height of your chimney to help improve the chimney draw.

  7. Consider Using a Chimney Cap - A chimney cap helps to prevent debris buildup and downdrafts caused by adverse weather conditions.

  8. Use draft regulators - Installing draft regulators helps improve and control drawing.

  9. Eliminate Competing Air Sources - Ensure that other appliances, like fans, do not compete with the chimney for airflow. You’ll also need to switch off the air extraction in the kitchen.

  10. Use Adjustable Air Vents - If your chimney or stove has adjustable air vents, adjusting them can help to improve the draw.

Final Thoughts

A bad draw from your chimney can be a serious problem and is not to be underestimated. However, by following good chimney flue installation practices, you can ensure that you get a good draw from your chimney.

As a closing thought, insufficient fresh air entering the room results in underpressure in the room: open a window to see if that solves the problem of the poor draft.

In this article, we've looked at several things related to bad draws. If you still have a problem and want expert advice, feel free to contact us.