Heatmaster/American Gas Log, LLC • 16-1012 • Rev D. 03/2018
5
Asphyxiation Risk
This appliance produces carbon monoxide
(CO).
• The free opening areas (in square inches)
of the chimney damper as shown in the
following tables must be met.
• User must make sure damper is locked
open.
• The installer is responsible to ensure
proper ventilation of flue gases before
appliance is used.
Fire needs to draft properly for safe
operation.
WARNING
Table 1 for Factory Built Fireplaces
Free Opening Area (in square inches) of Chimney Damper for Venting combustion Products from Decorative
Appliances for Installation in Solid Fuel Burning Fireplaces.
Chimney Ht.
(Feet)*
18 in. Log Set
LP Gas
18 in. Log Set
Natural Gas
24 in. Log Set
LP Gas
24 in. Log Set
Natural Gas
30 in. Log Set
LP Gas
30 in. Log Set
Natural Gas
10
28.3
28.3
35.3
not approved
44.2
not approved
15
21.2
21.2
26.4
38.5
32.2
45.4
20
18.1
18.1
22.1
31.2
26.4
37.4
25
15.9
15.9
18.1
27.3
22.9
31.2
30
14.5
14.5
17.3
24.6
20.4
28.3
35
13.2
13.2
15.9
22.1
18.9
25.5
40
12.6
12.6
15.2
20.4
18.1
23.8
Table 2 for Masonry Built Fireplaces
Free Opening Area (in square inches) of Chimney Damper for Venting combustion Products from Decorative
Appliances for Installation in Solid Fuel Burning Fireplaces.
Chimney Ht.
(Feet)*
18 in. Log Set
LP Gas
18 in. Log Set
Natural Gas
24 in. Log Set
LP Gas
24 in. Log Set
Natural Gas
30 in. Log Set
LP Gas
30 in. Log Set
Natural Gas
6
41.7
41.7
49.2
64
56.6
71.4
8
38.7
38.7
45.5
59.7
52.4
66.9
10
35.2
35.2
41.7
54.3
48.2
60.2
15
32.0
32.0
37.7
48.8
43.2
54.1
20
28.8
28.8
34.3
44.4
39.8
49.1
30
26.5
26.5
31.2
40.3
35.9
44.5
* Height is measured from the hearth to the top of the chimney.
Minimum height is 6 ft.
G. Negative Pressure
Negative pressure results from the imbalance of air avail-
able for the fireplace to operate properly. Causes for this
imbalance include:
• Exhaust fans (kitchen, bath, etc.).
• Range hoods.
• Combustion air requirements for furnaces, water heaters
and other combustion appliances.
• Clothes dryers.
• Location of return-air vents to furnace or air
conditioning.
• Imbalances of the HVAC air handling system.
• Upper level air leaks: recessed lighting, attic hatch
opening, duct leaks.
Table 3 for Minimum Fireplace Dimensions
Burner
Style
Front
Opening
Depth
Height
Rear
Width
Natural
BTU
Propane
BTU
SBS18
27 In.
16 In.
18 In.
19 In.
44,000
40,000
SBS24
34 in.
20 in.
18 in.
22 in.
73,000
61,000
SBS30
40 in.
20 in.
18 in.
29 in.
80,000
70,000
SBSIII18
32 in.
23 in.
22 in.
21 in.
88,000
80,000
SBSIII24
34 in.
23 in.
22 in.
22 in.
88,000
80,000
SBSIII30
40 in.
23 in.
22 in.
29 in.
92,000
82,000
