Q I have glass doors on my wood-burning fireplace. Because they're dated, I'd like to remove them. But do they actually provide enough insulation to justify keeping them? Is there an alternative?
A Yes, glass doors reduce the amount of warm air leaking from your house when the fireplace is not in use. Fireplace dampers, when closed, do that, too. But they're a crude air seal compared with good glass doors. Dampers permit a good deal of heated air (think dollar bills) to escape up the chimney over the winter.
Gas inserts and EPA-rated wood-burning inserts can provide a tighter seal and improve the efficiency and comfort of the fireplace as a heating appliance. And they can give your fireplace that updated appearance you're looking for.
An alternative to the doors for use when there's no fire is the Chimney Balloon, an inflatable device that sits out of sight in the chimney above the hearth opening (around $48). For more information, go to www.chimneyballoon.us.
Or you can make a decorative cover or "plug" that seals the hearth opening. It's a frame with a decorative room-side surface of antique metal stampings, decorative wood, ceramic mosaics, etc. The other side is the utilitarian, fireproof hearth-side surface. The interior can hold an insulation material such as fiberglass batting. The frame conforms to the opening to the hearth. The hearth-side outer edge needs a gasket to seal to the fireplace walls. It's critical to remove all ash and coals prior to inserting the plug, and permit all fireplace surfaces to drop to room temperature before installing it.
Simply removing the glass doors is likely to increase your heating bill and carbon emissions (soot) in your home. So unless you're upgrading to a gas or EPA-rated wood insert, or adding an alternative, keep the doors.
Includes information from Phil Smith, Minnesota Office of Energy Security.