Monessen Hearth Vent-Free Fireplace Systems DBX24C* Installation And Operating Instructions Manual page 10

GENERAL INSTALLATION INFORMATION
Figure 3 - Sample Room for Determining the Maximum Heater Rating
The following formula can be used to determine the maximum heater rating per the definition of unconfined space:
Consider two connecting rooms with an open area between, with the following dimensions:
BTU
If there were a door between the two rooms the calculation would be based only on the room with the heater.
If the area in which the heater may be operated is smaller than that defi ned as an
unconfi ned space or if the building is of unusually tight construction, provide adequate
combustion and ventilation air by one of the methods described in the National Fuel
Gas Code, ANSI Z223.1, 1992, Section 5.3 or applicable local codes.
10
(L1 + L2) Ft x (W) Ft x (H) Ft.
/
BTU
=
Hr
L = 15 1 /
1 2
1
/ (15 / + 12) x (12) x (8)
2
=
Hr
1
/ (15 /
BTU
2)
=
Hr
50
Ft., L = 12 Ft., W = 12 Ft., H = 8 Ft.
2
x 1000 = 52800
50
x (12) x (8)
x 1000 = 29760
50
/
BTU
x 1000
Hr
/
BTU
Hr
/
BTU
Hr
33D4047