By Bill & Kevin Burnett
Q: When our house was built in the 1930s, the fireplace was put in without a damper. There is also a glass-door fire screen that can be closed.
We get an odor of ashes even when the fireplace is not being used and has been cleaned. It is especially prevalent when we have a high-pressure layer in the area.
Do you have any suggestions about how to prevent the smell or mask it? We do not want to install a damper because we are afraid it will change the draw of the fireplace.
A: We encourage you to reconsider your decision not to install a damper. If you have a normal firebox, about 3 feet wide and 2 feet deep with a normal flue, you should have no problem with draw when the damper is opened.
Seasonal high-pressure ridges mean clear skies and cold air. Warm air rises and cold air falls. We think you're getting a downdraft through your damperless chimney.
The glass doors on your fireplace are preventing the relatively warmer air in the house from escaping up the flue and counterbalancing the cold air from outdoors. This is good for your heating bill, but results in the smell of ashes from the firebox. The glass doors are not airtight, hence the odor.
You don't have to hire a mason to rip into your 1930s vintage fireplace. We suggest that you install a chimney cap with an integrated damper. You don't have to touch the firebox other than to attach a chain mechanism allowing you to manually open and close the chimney top damper.
A chimney cap/damper is a spring-loaded metal cover that retracts to form a seal on top of the chimney when the fireplace is not in use. A chain is threaded down the chimney and bolted to a lever in the firebox, allowing the damper to be opened and closed from inside.
When you want a fire, simply undo the chain and the cap opens, allowing the smoke to escape. The draft of your fireplace should not be affected; the odor should be gone; and you'll have the added benefit of restricting the flow of warm air up the chimney.
A modern masonry chimney is constructed of two parts. The brick or other material that you see from the ground encases a flue of tile liner that you don't see.
Liners are fire clay pipe segments about 2 feet long that are joined together with mortar. Liners provide another line of defense against the heat of a roaring fire. We've seen chimneys with and without liners. Kevin's 1879 Victorian and Bill's 1920s Craftsman did not have liners in their chimneys. Our childhood home in San Leandro, Calif., did.
Your 1930s home was built early enough that it may not have a liner. It's also old enough that some of the mortar holding the brick could have deteriorated. We suggest you contact a licensed masonry contractor to get an opinion about the condition of your chimney and whether this solution is right for you. Check with a fireplace shop or heating supply company for a local distributor.
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