. Top Dampers with Chimney Caps
Whenever your top damper is open, rain or unwelcome visitors like birds, squirrels, bats, or rats can enter. The best solution is to install a chimney cap that is compatible with your top damper.
If you have neither a chimney cap nor a top damper, the best solution is to install a combination chimney cap damper.
Single Flue Chimney Cap Damper
Single flue chimney caps are attached to the flue pipe by set screws or by a clamp like a hose clamp. The chimney cap needs to be large enough to fit over the damper and its mounting flange, but small enough for the set screws or clamp to secure the chimney cap in place.
You may be able to use a single flue chimney cap if the mounting flange of your damper does not extend outside the edges of the flue pipe. The chimney cap needs to be at least one inch taller than the damper when it is in its open position. For example, if your flue pipe is 13” by 13” and the mounting flange of the damper is no larger than 13’ by 13”, and the height of the damper when open is 7” you can use a single flue cap made for a 13” by 13” flue pipe, with an 8” screen height.
The very popular Lyemance dampers and Lock-Top dampers are available with single flue chimney caps made to fit 8” by 13”, 13” by 13” , 13″ by 17″ or 8” by 18” flue pipes. Each chimney cap damper is made with 24 gauge, 304 alloy stainless steel. They have an 8” screen height and come with a lifetime warranty.
For top mount chimney caps:
In some cases, a single flue chimney cap will not fit over the mounting flange of the damper. This situation calls for a top mount chimney cap. That is, one that fits over the damper and flue and attaches to the chimney crown. You fasten top mount chimney caps to the chimney crown with self-tapping concrete screws.
To select a top mount chimney cap, measure the sides of the damper’s mounting flange and the length and width of the chimney crown. The chimney cap needs to be bigger than the mounting flange of the damper, but smaller than the entire chimney crown, and taller than the damper in its open position. For example, if you’re the mounting flange of your damper measures 13” by 18”, you can use a top mount chimney cap that is at least 14” by 19”.
To get the screen height of the chimney cap, measure from the chimney crown to the top of the damper in its open position. Add an inch of height to make sure the damper can operate freely. The screen height needs to be taller than the height of the flue pipe plus the height of the damper in its open position. For example, a damper that stands 13” above the chimney crown would need a top mount chimney cap with a 14” screen height.
Do it Yourself with a Chimney Cap Damper:
Installing a chimney cap over your top damper is a very easy DIY project. It requires only ordinary hand tools, a ladder, and common sense safety precautions. Installing a combination chimney cap damper does take a bit longer, but it is also a do-it-yourself project.