Five Ways To Stop A Cold Downdraft In Your Fireplace

Hearthstone Clydesdale Wood Insert


January 12, 2017

This time of year we get a lot of calls regarding cold air coming into homes from the fireplace. Before we talk about solutions to this very common problem, its important to understand why this happens


A home has a way of breathing where hot air rises and cold air comes in by the way of least resistance and natural pressure. The hot air that rises creates a higher pressure at the top of your home, and lower pressure at the bottom of your home. In these low-pressure areas at the bottom of your home, air will try to find a way in. Fireplaces are a common source of least resistance, especially when they are in the basement due to it being a low point in the home and again the hot air rising.

Also affecting pressure are appliances like furnaces, hot water heaters, fans, and central vacuum systems. Operating these may reduce inside air pressure, especially when they are not properly vented.

Now that we know the cause of this, what can you do to stop air from coming down your chimney?

5 Solutions For Chimney Air Leaks

  1. Make sure there is sufficient air supply to your furnace and water heater. If your appliances are not vented to the outside, you may be reducing the air pressure making the problem worse.
  2. Install an energy-efficient damper like a top mounting damper to seal off the flue completely when not in use, Note: These are not recommended on gas log sets.
  3. If the fireplace has a rear vent make sure it is sealed off when not in use.  These vents are installed for secondary air intake and make sure there is enough oxygen for combustion in your fireplace.  A lack of oxygen will often create a backdraft that allows smoke to come into the home, so make sure you unseal these when you are ready to light a fire!
  4. Seal all broken window caulking and door seals. This will help the pressure inside your home.
  5. Last, make sure your damper is closed 🙂 

Written By Steve May

Steve May founded Chimney Works And Rocky Mountain Stoves in October of 2001. Steve is an entrepreneur at heart, and avid outdoorsman, and a proud father of 5.

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