www.desatech.com
113900-01D
6
AIR FOR COMBUSTION
AND VENTILATION
Continued
WARNING: If the area in
which the firebox and gas log
heater may be operated is
smaller than that defined as
an unconfined 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/NFPA 54 Section 5.3
or applicable local codes.
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoin-
ing unconfined space. When ventilating to
an adjoining unconfined space, you must
provide two permanent openings: one within
1" of the ceiling and one within 1" of the
floor on the wall connecting the two spaces
(see options 1 and , Figure 4). You can also
remove door into adjoining room (see option
3, Figure 4). Follow the
National Fuel Gas
Code ANSI Z223.1/NFPA 54, Section 5.3, Air
for Combustion and Ventilation
for required
size of ventilation grills or ducts.
Figure 4 - Ventilation Air from Inside
Building
Or
Remove
Door into
Adjoining
Room,
Option
3
Ventilation Grills
Into Adjoining Room,
Option 2
Ventilation
Grills
Into Adjoining
Room,
Option 1
12"
12"
3. Add the Btu/Hr of all fuel burning appliances
in the space.
Vent-free heater
__________ Btu/Hr
Gas water heater*
__________ Btu/Hr
Gas furnace
__________ Btu/Hr
Vented gas heater
__________ Btu/Hr
Gas fireplace logs
__________ Btu/Hr
Other gas appliances* + ________ Btu/Hr
Total = ________ Btu/Hr
* Do not include direct-vent gas appliances.
Direct-vent draws combustion air from the
outdoors and vents to the outdoors.
Example:
Gas water heater
_________ Btu/Hr
Vent-free fireplace
+ ________ Btu/Hr
Total = ________ Btu/Hr
4. Compare the maximum Btu/Hr the space
can support with the actual amount of Btu/Hr
used.
_______ Btu/Hr (maximum the space can
support)
_______ Btu/Hr (actual amount of Btu/Hr
used)
Example:
51,00 Btu/Hr (maximum the
space can support)
79,000 Btu/Hr (actual amount of
Btu/Hr used)
The space in the above example is a confined
space because the actual Btu/Hr used is more
than the maximum Btu/Hr the space can sup-
port. You must provide additional fresh air. Your
options are as follows:
A. Rework worksheet, adding the space of an
adjoining room. If the extra space provides
an unconfined space, remove door to adjoin-
ing room or add ventilation grills between
rooms. See
Ventilation Air From Inside
Building
below.
B. Vent room directly to the outdoors. See
Ventilation Air From Outdoors
.
C. Install a lower Btu/Hr heater, if lower
Btu/Hr size makes room unconfined.
If the actual Btu/Hr used is less than the
maximum Btu/Hr the space can support, the
space is an unconfined space. You will need
no additional fresh air ventilation.
40,000
39,000
79,000
