40
Rev. 05/2020
Firebox Door
Principles of the Firebox Door
The firebox door is HTF cooled to prevent warping of the
door. It also acts like a water jacket, absorbing heat from
the fire, and placing that energy into the HTF. Being HTF
cooled, the front of the firebox door will never be hotter
than the HTF. The cold outside atmospheric air is drawn
over the warm surface of the firebox door, by the
combustion blowers, which is then warmed and forced into
the firebox as warmed combustion air. This lessens the
time needed for the interior of the firebox to reach that high
smoke burning temperature. It is important that the firebox
door seal maintains an airtight seal.
Operation of the Firebox Door
HTF from the main water jacket flows in a loop between
the firebox door and the water jacket by natural thermal
siphoning. Since there is no pump involved, there is very
little pressure. During this process, the HTF cools the door
and the HTF in the door is heated.
Maintenance / Result
A properly adjusted firebox door will not allow smoke to enter or escape the firebox.
Maintain a tight seal all around the perimeter of the firebox door at all times. There may be
times when the perimeter of the firebox door will build up with “creosote strings,” especially
along the bottom.
To keep the perimeter clean, occasionally scrape down to the steel.
Do not cut,
scrape or
disturb the actual soft, pliable seal. Keep the door correctly adjusted on the hinges so that
the pliable seal is being forced against the firebox ledge. Keep all nuts and bolts on the
handle, latch and hinges properly adjusted.
The seal itself consists of a rope in the groove of the firebox door, covered with high
temperature silicone.
Failure to manage and maintain the firebox door could result in premature replacement of
parts and a buildup of creosote.
Firebox Door Handle
Firebox Door Handle
