At Chimney Safety Institute of America, we commonly get asked about whether homeowners should leave the glass doors on their fireplace open or closed.
Keep in mind, the glass used with a wood stove is different from that used with a fireplace.
A fireplace uses tempered glass that is resistant to physical shock.
A wood stove uses a pyro-ceramic glass that is resistant to thermal shock.
That is why we DO NOT recommend closing the glass doors on a fireplace while there is a fire.
The glass can shatter, sending hot shards of glass into the room.
It also elevates the temperature of the firebox and flue by greatly reducing the volume of air moving through the venting system.
You can close the glass doors on the fireplace AFTER the firewood has turned into ash or small coals. (And be sure you’re keeping an eye on that wood fire; wait for it to have burned out before heading to bed. A wood fire left untended isn’t safe.)
CSIA also recommends that when in operation, use a gate or protective barrier to keep curious children from touching the hot glass. This protective barrier is commonly referred to as a fireplace screen.
By the way, this is another good opportunity to remind everyone about a new rule in effect (as of Jan. 1, 2015) when all glass-fronted gas hearth appliances – that means gas fireplaces and glass-fronted gas heaters – now require a protective barrier if their glass surface temperature exceeds 172 degrees Fahrenheit (F). Learn more from the Hearth Patio Barbecue Association website.
Please make sure and contact a qualified professional, such as a CSIA Certified Chimney Sweep, to inspect your chimney and appliance before use. Our 1,500 CSIA chimney sweep technicians can also help newcomers with home fireplace use, and diagnose any issues. Go to CSIA.org/search to find a sweep in your zip code.