Desa VN600BA Safety Information And Installation Manual page 6

AIR FOR COMBUSTION
AND VENTILATION
Continued
DETERMINING FRESH-AIR FLOW
FOR FIREPLACE LOCATION
Determining if You Have a Confined or
Unconfined Space
Use this work sheet to determine if you have
a confined or unconfined space.
Space: Includes the room in which you will install
fireplace plus any adjoining rooms with door-
less passageways or ventilation grills between
the rooms.
1. Determine the volume of the space (length
x width x height).
Length x Width x Height =__________cu. ft.
(volume of space)
Example: Space size 20 ft. (length) x 16 ft.
(width) x 8 ft. (ceiling height) = 2,560 cu. ft.
(volume of space)
If additional ventilation to adjoining room
is supplied with grills or openings, add the
volume of these rooms to the total volume
of the space.
2. Multiply the space volume by 20 to determine
the maximum Btu/Hr the space can support.
________ (volume of space) x 20 = (Maxi-
mum Btu/Hr the space can support)
Example: 2,560 cu. ft. (volume of space) x
20 = 51,200 (maximum Btu/Hr the space can
support)
3. Add the Btu/Hr of all fuel burning appliances
in the space.
Vent-free heater
Gas water heater*
Gas furnace
Vented gas heater
Gas fireplace logs
Other gas appliances* + _________Btu/Hr
Total
* Do not include direct-vent gas appliances.
Direct-vent draws combustion air from the
outdoors and vents to the outdoors.
Example:
Gas water heater
Vent-free heater
Total
4. Compare the maximum Btu/Hr the space
can support with the actual amount of Btu/Hr
used.
_______ Btu/Hr (maximum can support)
_______ Btu/Hr (actual amount used)
6
__________Btu/Hr
__________Btu/Hr
__________Btu/Hr
__________Btu/Hr
__________Btu/Hr
= _________Btu/Hr
50,000
__________Btu/Hr
10,000
+ _________Btu/Hr
60,000
= _________Btu/Hr
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Example: 51,200 Btu/Hr (maximum the
space can support)
60,000 Btu/Hr (actual amount of
Btu/Hr used)
The space in the example is a confined space
because the actual Btu/Hr used is more than the
maximum Btu/Hr the space can support. 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.
B. Vent room directly to the outdoors. See
Ventilation Air From Outdoors, page 7.
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 maxi-
mum Btu/Hr the space can support, the space
is an unconfined space. You will need no ad-
ditional fresh air ventilation.
WARNING: If the area in
which the heater may be oper-
ated 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 adjoining
unconfined space. When ventilating to an
adjoining unconfined space, you must provide
two permanent openings: one within 12" of the
ceiling and one within 12" of the floor on the
wall connecting the two spaces (see options 1
and 2, Figure 2, page 7). You can also remove
door into adjoining room (see option 3, Figure
2, page 7). 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.
110720-01M