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Troubleshooting - Draft/Fireplace Smoking Problems

Wind-related smoking:

This can usually be solved by installing a Vacustack® cap. However, the problem must be qualified to make sure that it is only the wind being blown down the flue that causes this problem. Usually, the harder the wind blows the worse the problem is. The Vacustack® works by actually creating an updraft due to the way the wind hits the cap.

Wind-loading smoking:

This is a pressure issue that’s caused when the wind hits the side of the house that the fireplace/stove is located on. For instance, the fireplace/stove is located on the wall of the north end of the house. When the wind blows from the house it hits the north side (high pressure side) and circles around the house. On the south side, there’s a negative pressure area which acts as a suction pulling smoke or cold air down the flue. On this side of the house the doors will be hard to open or shut. This can usually be proven by opening a window on the windward side (north). If this is the case, an Air Supply Ventilator may solve the case.

Fireplace Smokes on Start-Up and When Fire Dies Down:

This often happens with a fireplace that’s located on the outside wall of a home. Cold air can usually be felt coming into the home through the fireplace damper. In this instance, the flue usually needs to be pre-warmed. This can be accomplished with a newspaper rolled up, lit, and held near an open damper. A hair dryer is another way to start warm air moving up the flue. Wax firebricks, Gelled Fire Starter, or Firestarter Blocks also help to warm up the flue with little smoke. Another option is installing an Exhausto® Fan which ensures draft on start-up as well as avoiding smoke when the fire dies down and everything cools again.

Fireplace Starts and Burns Fine – then Smokes after a While:

This is usually caused by insufficient oxygen. A fireplace can use the combined air leaks of a 36" circle. Older homes that haven’t been sided, have original leaky windows, and have poor insulation may have this combined “combustion air” available. Modern homes or homes with siding, house wrap, insulation, tight windows and doors only have a combined air leak of 8" which is the size of a dinner plate. That’s not enough for the average fireplace. Usually air must be introduced and sometimes one or more Air Supply Ventilator may be enough to supplement the fireplace. The air requirement can be tested by cracking a window open and gradually opening it to the point where the fireplace stops smoking. An Exhausto® Fan may also be installed. If properly adjusted, it shouldn’t use any more air than when the fireplace is drafting correctly. However, be cautious that it doesn’t remove combustion air that another appliance, such as a furnace or water heater, need to function properly.

Fireplace Smokes all the Time:

A constantly smoking fireplace is usually indicative of a construction issue. The flue should be approximately 1/10th of the fireplace opening. If it’s much smaller, it could cause the fireplace to smoke. A Smoke Guard, installed at the top width of the fireplace opening, may cut down on the opening enough to correct the flue to fireplace ratio. Another instance where the Smoke Guard may help is if the damper is too close to the fireplace opening or if the fireplace is taller than it is wide.

Sometimes, a top sealing damper reduces the flue opening enough to cause an otherwise working fireplace to smoke. Installing a Smoke Guard may remedy the situation.

Our Seal Tight Damper® can allow up to 15% more airflow than other similar dampers. The Energy Top® opens as much as 81% higher than the competition ensuring it’s less restrictive than competitive dampers.

Fireplace Smokes after a New Cap was Installed:

If a cap has insufficient screen height or if the draft is marginal it could cause the fireplace to smoke. A good rule of thumb is that the lid of the cap should be a minimum of 5” taller than the tallest flue tile. Sometimes, when multiple flues are present, a basement stove or fireplace will pull smoke or a smoky smell down into the basement. Usually, only cold air was pulled down previously. With a cap in place, it captures the smoke long enough for the smoke or smell to be present. For a fireplace, a Seal Tight® Damper might fit under the cap. This tight sealing damper usually solves the problem.