Damper install a DIY deal
A fireplace certainly is a pleasant and attractive feature for a home, but it can allow many unwanted things to enter through the chimney. Cold air and, depending where you live, an occasional bat are common.
Most fireplaces have a damper in the throat of the chimney just above the firebox. This is designed to keep out pests and keep cold air from leaking into your home when a fire is not burning and the damper is closed. If installed properly, it can be quite effective. The problem is after it gets old, it no longer seals well. This can be caused by creosote or other deposits where the damper sits in its frame. Also, when a damper gets very old, it can rust through, leaving gaps large enough for a bat or insects to squeeze through.
It is possible to replace a chimney throat damper, but installing a flue-top damper makes more sense and is a relatively easy do-it-yourself project. A good quality flue-top damper costs between $150 and $300, depending on the size of the flue opening at the top of the chimney.
There are two basic damper designs.
One is a pop-up design and the other is a hinged design. When they are closed, they seal well and prevent animals from entering the chimney.
Both designs include a stainless steel cable, which runs down the chimney into the firebox. This cable is used to open and close the damper. The cable should last many years and can easily be replaced when it wears out. A stainless steel cable is available at hardware stores or boating supply outlets. If the cable breaks, the damper automatically moves to the open position.
Damper kits come with a metal frame that is mounted over the top of the chimney flue. They are spring-loaded, so they open when you release the tension on the stainless steel cable.
The pop-up design has diagonal springs, which keeps it level as it opens. Most flue-top damper manufacturers recommend gluing the metal damper frame to the top of the flue with high-temperature silicone sealant. This should be adequate to hold it in place. However, if you prefer to screw it to the flue with brackets, use stainless steel brackets and screws.
When working with flue tile, keep in mind it is brittle. Use a tiny masonry drill to make a pilot hole for the bracket screws. Follow this with a 1/4-inch drill bit to finish the holes. Don't tighten the screws that hold the brackets to the flue too much. Apply ample silicone sealant and press the damper frame down into the sealant, eliminating all voids. Attach the damper housing to the brackets to secure the damper assembly in place.
See, that didn't take too much effort. And now that your new flue top is in place, you can begin enjoying the feeling that no unwanted visitors will be making their way down your chimney.
