On the one hand we want the fireplace to work properly when there’s a fire in it, drawing the smoke out through the chimney and not spilling smoke into the house; and on the other hand we want the chimney to stop drawing when there’s no fire, so we don’t lose a lot of heat. Chimney fans and top-sealing dampers help provide a solution.
What's wrong with traditional dampers?
Traditional construction of brick or stone fireplaces includes a “throat damper” just above the firebox. This is an iron or steel frame with a plate that opens by pushing a handle or turning a knob. You might think of it as the lid of a cast-iron pot, in the sense that it closes, but not tightly. Some fireplaces have no damper at all.
The chimney is designed to draw warm air up and out. If you close a throat damper when you’re not using the fireplace you’ll cut heat loss, but you’ll still lose a lot of heat. After all, it’s just a rough-cast metal plate resting over the opening. There’s no seal. Around this loose-fitting closure, the chimney draws warm air up and out all winter long.
The Top-Sealing Damper.
A top-sealing damper is just what it sounds like: a damper installed at the top of the chimney, with a high-temperature gasket to keep warm air in and cold air out. A stainless-steel cable connects to a handle in the fireplace, so it’s easy to open and close the damper. It’s also easy to see if it’s open or closed.
Conservation efforts have resulted in a range of much improved construction products such as doors an windows designed to minimize heat loss (and in the summer to help keep the house cool). If the throat damper is like a rough-fitting iron lid, the top-sealing damper is like a pressure-cooker lid with a high-temperature rubber seal. A top-sealing damper reduces heat loss, saves you money, and helps make your house more comfortable.
Why have the damper at the top of the chimney?
Closing the chimney at the top, instead of at the “throat” of the fireplace, reduces water damage by keeping water out of the flue when the fireplace isn’t in use, and blocks entry of animals (birds, raccoons, etc.). And maybe best of all, when it’s time to start a fire the flue tends to be a bit warmer, because winter air hasn’t been circulating in an open flue above the throat. This means it’s a little easier to get the fire going: a little less work to get an upward flow of air.
What if my fireplace spills smoke into the room?
Saving energy is all well and good. But the other part of the picture, enjoying a nice fire on the hearth, is sometimes a bit more complicated. If all the pieces fit together nicely flue size, chimney height, firebox dimensions and so on the fireplace does its job: The fire burns, the smoke is drawn out, and you can sit by the fire and get warm. But sometimes the conditions aren’t perfect. If your fireplace spills smoke into the room, or seems sluggish, as if there just isn’t enough air flow to run a fire, an Exhausto Chimney Fan might be the solution.
A chimney fan is installed at the top of the chimney. Its variable-speed motor allows you to maintain an ideal draft, drawing all the smoke out. Simple and easy.
As part of a regular chimney inspection we will check your fireplace, identify what’s there now, and suggest the best options for improving energy efficiency and fireplace operation. Call (781) 585-5990 or Email us for an appointment to inspect your chimney.