This damper seals at the top of the chimney to prevent air from escaping the home when the fireplace is not in use.
This damper seals at the top of the chimney to prevent air from escaping the home when the fireplace is not in use.

What is a damper? Customers often call in saying that their “flue” is broken or needs to be repaired because it won’t work properly. The flue is actually what lines the chimney, whether that be clay tiles or a stainless steel liner. The damper, however, opens and closes manually to either keep the warm air of the house in when the fireplace is not in use or allow the smoke produced by the fire to exit. This being said, if the damper stops opening and closing properly, you experience problems.

Dampers are the cast iron plates that are attached to hinges at the top of the chimney. While lighting the fire, open the damper, then close it once the fire has gone out. Dampers can be traditional or top sealing and are usually operated by a lever or chain inside the home. Be sure that your damper fits well because any gaps between the damper and the walls of the flue system cause warm air to float up and out of the home, increasing energy costs.

Manual dampers are opened and closed by a handle outside of the flue system. Automatic dampers, conversely are controlled by a thermostat and operated by motors. Although automatic dampers are not necessary, can be expensive, and are not widely popular, it is very likely that they will become more widespread as time goes on seeing that society makes a constant push toward the automatic, hands-off type goods.

Zone dampers are very interesting, they control the flow of air in an HVAC cooling or heating system. By using a zone damper, efficiency and comfort can be improved. Heat can be directed to a particular floor or area of the house. Heating homes this way is the most efficient- heating just the rooms you are in allows you to save heat and energy while still enjoying the comforts of a warm home.

Realize that the damper and the actual building of a fire will function differently based on what conditions exist both outside and inside the home. Having certain windows open while you start a fire or having the damper at a particular angle will cause different results. Weather conditions also affect fires, seeing that barometric pressure is affected by the weather which ultimately affects the general “draw” of your flue system.

It is always prudent to have both a chimney cap and a damper installed in your chimney. A top-sealing damper, such as a Lock-Top system, essentially “plugs” the hole created by your chimney. Expensive air simply rises up the chimney and out of the home without one. A damper works in much the same way. Remember to always start fires with the damper open.

Clay Lamb

Clay Lamb is a Cincinnati Chimney Sweep contractor and the executive producer of the YouTube channel, podcast, and blog Ask the Chimney Sweep. He is also an award-winning educator and public speaker in the chimney and fireplace industry.

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Clay Lamb

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2 thoughts on “Fireplace Dampers

  1. Mr. Lamb,
    I have a wood burning fireplace. My plan was to convert it to a gas fireplace…, then I found out how much that cost. GULP. So, now I’m looking into other options. I wanted a gas fireplace for the convenience; I could turn it off and on and leave the room without worry. My question is, is there some way to do that with a wood burning fireplace? Or have the damper automatically close when the fire goes out? Any information you could provide would be much appreciated.
    Thank you,
    Sarah

  2. First off lets start with the last thing. I’ve never seen anything with wood burning appliances or equipment. (I think you’re a perfect candidate for a direct vent gas fireplace or insert). The price may seem extremely high but your return on investment would be a great value to you. The convenience of a remote control and a beautiful warm flame are well-worth the investment. I have two of them and my wife and I enjoy them constantly. Best to you on your heating journey.

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