If you’re not careful, the answer is ‘yes’, the glass on your fireplace or stove can crack or break. It’s important to keep the glass clean, maintain the gasket in good repair and be careful and avoid breaking or cracking the glass when reloading the fireplace. Here’s why…
TWO TYPES OF GLASS:
Your fireplace (or stove) will have one of two types of glass; tempered or ceramic. The bi-fold doors on your zero clearance (ZC) wood burning fireplace are likely tempered glass. The gasketed door on an EPA certified insert, stove or ZC fireplace uses ceramic glass. So, what’s the difference between the two? Among other things, the price! Ceramic glass is significantly more expensive than tempered glass.
Both types of glass will take the high temperatures of a wood burning fire. But ceramic glass is much stronger than tempered glass of the same thickness. Ceramic glass can withstand very rapid thermal changes and temperatures of 1000°F.
EPA certified appliances use sealed, ceramic glass to help control the burn rate or the amount of combustion air allowed to the fire. There should be no air leaking around the edge of the glass. All combustion air is supplied to the fire via the primary air control and/or an appropriate outside air kit.
A QUICK SIDEBAR:
Never attempt to force a 16” log into a 15” firebox. When you’re cutting wood, it’s always a good idea to go a couple of inches smaller. If your fireplace or stove can take a 20” log, you’re smart to go with an 18” log length. If the specs say 16” logs, cut it 14”. You get the idea!
Never allow any burning wood to contact the glass on your fireplace. Under no circumstances, never force the door closed after refueling the appliance. Ceramic glass is expensive. It’s strong, but it can and will break, so be careful with it.
WHAT IS MEANT BY “SEALED AND GASKETED”?
If the glass on your fireplace cracks or breaks, order the correct replacement glass from your WE LOVE FIRE dealer. We will help direct you to the proper type of glass and will order the correct size for your door(s). Replacement glass is usually supplied by the manufacturer of the fireplace. It will be cut specifically for your model to fit perfectly.
When replacing ceramic glass, it must be sealed to the door frame. This can be done either at your WE LOVE FIRE dealership or, with the correct materials, by the do-it-yourselfer at home.
Graphite impregnated, ceramic fiber rope gasket is the most common type of gasketing material used for wood burning fireplaces, stoves and inserts. It comes in several sizes from ¼” to 1” diameter. Most doors will have a channel or groove where the rope gasket must be positioned. A gasket cement or silicone is applied in this channel to keep the rope gasket secured in place.
The main function of the gasket is to seal the room air from the firebox. The air for combustion on wood burning fires is carefully measured by the equipment’s primary air control. There should be no leakage around the glass or the gasketed door on your fireplace, stove or insert.
WOOD VS GAS:
Ceramic glass is not limited to wood burning appliances. Most gas fireplaces, stoves and inserts use ceramic glass, too. The ceramic glass is typically sealed to a steel frame by an adhesive backed gasket. Since direct vented gas appliances use 100% outside air for combustion, it is important to inspect the gasket material occasionally and replace it as needed. The best time to do this is when cleaning the inside of the glass.
CLEAN THE GLASS!
And speaking of cleaning the glass, whether it’s ceramic or tempered glass, keeping the inside of the glass clean is important. Both ceramic and tempered glass get dirty. By keeping it clean, you will be able to regularly inspect the gasket seal. And, in addition to that soothing heat, you will enjoy a beautiful view of the fire.
There are separate glass cleaners available for wood burning appliances and gas equipment. A bottle will last a long time and is inexpensive. Your WE LOVE FIRE dealer has it in stock.
Remember the ceramic glass on your fireplace, stove or insert can be quite expensive to replace. $200 – $300.00 is not uncommon. So, easy does it!
Joseph G. Bodden is a Wisconsin native and is semi-retired after 40+ years in marketing, sales and technical customer service work. Over 28 of those years have been in the fireplace industry, many as the Hearth Division Manager in an organization that operates two retail shops. During that time, Bodden was certified by the National Fireplace Institute in wood & gas technologies. He was also selected several times by Hearth & Home magazine as a judge for the annual VESTA awards that recognize manufacturers creativity and innovation in product design and technology.
One thing that Joe particularly finds fulfilling is explaining fairly complex subjects to fireplace customers and steering them to specific products that will satisfy their objectives. There’s nothing like unsolicited positive feedback from a happy customer!
Bodden lives in the scenic driftless region in southwest Wisconsin with his bride of 48 years. He enjoys the outdoors, playing guitar and spending time with their grandson and five granddaughters.
