I work for a company that makes glass for fireplaces and we often get questions from customers about whether glass bi-fold doors on a fireplace should remain open when the fire is going or should be closed. Is there a safety reason for one or the other? A performance reason?
Is there a safety reason for one or the other? A performance reason?
Be sure to read any documents (instructions or user manual) that came with the doors (if they are a separate product) or stove (if the doors are built in to a product like a wood burner).
Any safety instructions will be in those documents.
As a manufacturer of glass for doors you should be referring those customers with such questions to their documentation or to the manufacturer of the doors.
As for performance:
A popular misconception is that fireplace doors are able to increase the efficiency and heat output of masonry fireplaces.
The purpose of glass doors on a fireplace is not to increase heat output or efficiency of open fires.
Manufacturers of fireplace doors typically state that the doors must be open during and for a while after fires. Studies and research have also shown that closed fireplace doors do not increase either heat output or efficiency
3 Really Good Reasons to NOT Burn a Fire with Your Doors Closed
You will shatter your glass doors. Standard tempered glass is made to withstand temperature up to about 450 degrees. Typical fireplaces reach temperatures between 500 and 1200 degrees. Ceramic glass is designed to withstand temperatures up to about 1400 degrees.
It is not safe. Masonry fireplaces are all brick or stone which absorb and reflect the heat much better than metal prefab fireplaces. Additionally, prefab zero clearance fireplaces are surrounded by wood which can be a combustible fire hazard, therefore have specific regulations regarding the ventilation of fireplace doors.
You lose the fire’s heat. With the doors closed 99% of the heat of your fireplace with go directly up the chimney.