Damper Choices

All fireplace doorsets normally come with some provision for allowing and controlling some room air to go into the firebox, so the fire has the air it needs to burn. That is called the damper. In relatively new homes (built after around 1985), houses have been built so extremely "tight" that very little air can leak into the house anywhere, something called infiltration. With that situation, many fireplaces did not work very well, because, in order for smoke and air to go up the chimney and out, other air had to infiltrate into the house to replace it. Because of that situation, nearly every fireplace in houses newer than that, probably have their own "outside combustion air intake" where the fire actually gets the air it needs directly from outdoors and not from the room. In this situation, whatever damper is in the fireplace doorset could permanently be left closed! In principle, a damper would not even need to be included in a doorset for such a fireplace.

The three common possibilities are: (they are not always all offered on any specific door model or by a specific manufacturer).

Hidden Damper. In recent years, this is by far the most common, and is the most likely standard damper on many "stock" door models. Where long ago, customers LIKED filigree areas, nowadays people want very narrow frames and the most glass as possible instead. With no filigrees to use as air intakes, the door manufacturers came up with "hidden dampers".
They're actually not quite hidden at all! If you look VERY closely at many of the photos, you will notice that the main door frame piece across the bottom is a fraction of an inch UP from where the side rails go. If that was 1/4" high, by 32" wide, that's 8 square inches of available opening, PLENTY for the air for a fire! (The SECRET of the hidden damper has been exposed!!!)
Non-Hidden Damper. (There is no actual name for it!) If you choose a door model that DOES include one or more filigree areas, that area is generally used for the air inlet area, and the damper is behind it to control that airflow. So, for doorsets WITH filigree areas, this is usually the STANDARD damper.
No Damper. The vast majority of STOCK doorsets include one of the above damper choices as a standard feature. You would just need to leave it closed! The CUSTOM doorsets also include a damper as standard, but usually offer an option of NOT having a damper installed. In that case, the fire could ONLY get its air from its separate air source, and would have no way of using room air unless the doors were opened!

JUCA's Built-In Fireplace Home Page is at: http://mb-soft.com/juca/indexf.html
JDoor's Fireplace Door Selector Page is at: http://mb-soft.com/juca/info/doors/firedoor.html

E-mail to: JDoor1@mb-soft.com