Whether you have a wood or gas fireplace, some problems may occur when it’s windy outside. It may be anything from hearing the wind blow in your chimney to having trouble lighting your fireplace or smoke back drafting inside the house.
How do these problems occur, and how can you fix them?
Wind Noises
Whether it’s the sound of the wind blowing across the top of your chimney, or the wind rushing down your chimney, you’re in for a good variety of unmelodious acoustics. Luckily, it’s usually a problem that’s easy to fix, and there are many solutions available.
A chimney balloon and a flue blocker are two fast and easy solutions. A chimney balloon is placed inside the chimney and is then inflated. It gets rid of the noise, keeps the cold air out and the warm air inside. A flue blocker works in the same way, except it’s easier to install than the chimney balloon. You push it in the narrow part of the chimney. The one thing to remember with these two options is that you have to remove them before using your fireplace. So, if you plan on using your fireplace at all, these are not options for you.
More permanent solutions to wind noises are the chimney cap and the chimney cowl. Both are fixed to the top of the chimney and are permanent. Every house is submitted to different conditions; what works for one might not work for another. While a chimney cap fixes the problem for some, it can make it worse for others. Sometimes the small holes in the cap act like whistle holes. A chimney cowl rotates with the wind, so it blows the wind in other directions before it even gets in your chimney. Both the chimney cap and the chimney cowl keep the rain out and stop small animals from going down your chimney.
Lighting Your Gas Fireplace
Wind gusts can make it difficult for you to light your gas fireplace, or even to keep it lit. These problems usually occur when there’s an imbalance of gas and oxygen in your unit.
If lighting your fireplace is an issue, listen to the wind gusts and try lighting it between two gusts. It might take a few attempts.
If you really can’t light it, or if, once lit, the flame floats off the burner or doesn’t stay lit, it means there’s too much air getting into your unit.
If the flame is small, transparent and blueish, it means you don’t have enough air in the unit.
All these issues can usually be resolved with a wind guard fixed over the end of your vent. Wind guards allow proper airflow while protecting against high winds and snow.
Back Drafts
Back drafts in wood fireplaces are trickier than the previous issues. It’s all a question of pressure and aerodynamics.
The wind is variable and unpredictable. While wind flowing over the top of a chimney can increase draft and pull gases from the chimney, it can also go down the chimney and produce backdrafts.
There are positive pressure and negative pressure. Positive pressure always goes into the void caused by negative pressure. You can compare negative pressure to a black hole; it sucks in everything around it.
When the wind flows around a house, aerodynamics usually causes positive pressure on the windward side, but negative pressure on the downwind side and both sides of the house parallel to the wind flow. There are three sides of the home surrounded by negative pressure, versus one side where there’s positive pressure. That means that whatever pressure is in your house gets out from leaks on the sides surrounded by negative pressure. More pressure gets out than what comes in, so your home depressurizes, which means that air will be sucked down the chimney. That creates a backdraft, or at the very least, venting problems.
Chimney height also plays a large part in proper venting. Building codes require that the chimney go up at least three feet above the highest point at which the chimney touches the roof. It must also be at least two feet higher than the tallest structure or roof surface within a horizontal distance of ten feet. These are the minimums required by law. They might need to be exceeded to get the desired performance.
If your chimney isn’t high enough, for example, if it’s installed in the single-story section of a two-story house and doesn’t comply with building codes, it can generate problems caused by pressure. When the wind blows against the two-story part of the house, it creates a positive pressure zone around the chimney, which pushes the airflow down the chimney. In cases like these, adding to the height of the chimney usually solves the problem.
Maybe your chimney was of the right height when your house was built but has anything since changed? Are there new trees nearby or have new buildings been added? It might just be that a chimney height change could be in order.
If your chimney is tall enough, installing a chimney cap with baffles will, in many cases, regulate the wind flow and fix the problem.
Be Ready for Winter
There’s nothing like a warm fire on a cold winter night. So, if you have some issues with chimney noises, problems lighting your fireplace or smoke coming into your house, ask a professional to come and take a look. This article simplifies the concept of wind pressure and aerodynamics, but in reality, it’s much more complicated. Many things can affect the pressure in the house. From where your home is situated to how it’s insulated.
The best thing to do when encountering a problem is to call a specialist. They analyze the situation thoroughly and find the solution best fitted to your needs. Once everything is up and going, you can then wait for winter, knowing you’ll have a nice fire when you come home.
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