If you wish to install some glass in your direct vent fireplace, then you have a choice between fitting ceramic glass and tempered, or safety glass. There are positives and negatives to installing both types of glass, and your decision should be between a primary source of heat for your room, or a simple decoration to brighten up your room. Before you choose between these types of glasses, you should take a little time to learn as much as you can about them.
This glass is probably the stronger of the two types of glass. It is able to withstand very high temperatures, up to around 1000 degrees centigrade, but it is also able to survive repeated changes between hot and cold, which is ideal in a fireplace. The glass also has little glare, and it is also possible to make the ceramic glass virtually transparent. Ceramic glass will show what is behind it, such as the flames and logs of a fireplace, but it will not be visible itself. It was originally used in telescopes and mirrors, so the material is definitely hard-wearing and long lasting. Ceramic glass is also used in other domestic appliances, including stove cooking tops, and pots, pans and dishes.
Tempered or Safety Glass
This glass is tempered through repeated heating and cooling. Swords were tempered by heating in a fire, and then plunging it into water, and tempered glass is made in much the same way. This makes it extremely tough, around five times harder than typical glass used in windows. It is also extremely resistant to heat. This kind of safety glass is used in ovens and on shower doors, and is well known for the unique way that it breaks by shattering into small oval-shaped pebbles. Tempered glass is also more opaque than ceramic glass, so any detailing on it can clearly be seen.
Choosing Ceramic or Tempered
The difference between the two glasses does lie very much in function and appearance. If you are looking for the ideal glass for the front of a functioning fireplace, then ceramic glass will probably be the best solution. Tempered glass will not allow heat to pass though it, while ceramic glass is able to allow more of the heat produced by your fireplace to reach into the room. Ceramic glass is more likely to transfer heat to you, rather than hold it in the fireplace.
However, if you are looking for something which is more decorative than useful, then tempered glass will probably be your preferred option. Tempered glass is rather reflective, so you will see it more easily on the fireplace, while ceramic will give you an clearer view of the fire and any vented logs. Tempered glass is also much cheaper than ceramic glass, so if you are looking for something just to give a better look to a fireplace, then it makes more sense to go with the one which is cheaper. There does not seem much sense in installing a glass which is both much more expensive, and much less visible on a fireplace which will be mostly decorative in function.