Desa VMH26TNC Outdoor Fireplace User Manual


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113111-01E 7

construction where:
 -
 




2


and
 
and
   






If your home meets all of the three criteria

Ventilation Air From Outdoors,

If your home does not meet all of the three
  Determining
Fresh-Air Flow For Fireplace Location

The National Fuel Gas Code, ANSI Z223.1.3/
NFPA 54 denes a conned space as a space whose
volume is less than 50 cubic feet per 1,000 Btu
per hour (4.8 m
3
per kw) of the aggregate input
rating of all appliances installed in that space and
an unconned space as a space whose volume is
not less than 50 cubic feet per 1,000 Btu per hour
(4.8 m
3
per kw) of the aggregate input rating of
all appliances installed in that space. Rooms com-
municating directly with the space in which the
appliances are installed*, through openings not
furnished with doors, are considered a part of the
unconned space.
* Adjoining rooms are communicating only if
there are doorless passageways or ventilation grills
between them.
AIR FOR COMBUSTION
AND VENTILATION
Continued
DETERMINING FRESH-AIR FLOW



Use this work sheet to determine if you have a
conned or unconned space.
Includes the room in which you will install
replace plus any adjoining rooms with doorless pas-
sageways 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) = 2560 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: 2560 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 replace ___________ Btu/Hr
Gas water heater* ___________ Btu/Hr
Gas furnace ___________ Btu/Hr
Vented gas heater ___________ Btu/Hr
Gas replace logs ___________ Btu/Hr
Other gas appliances* + ___________ Btu/Hr
Total = ___________ Btu/Hr
* Do not include direct-vent gas appliances. Di-
rect-vent draws combustion air from the outdoors
and vents to the outdoors.
Example:
Gas water heater ____________ Btu/Hr
Vent-free replace + ___________ 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: 51,200 Btu/Hr (maximum the space
can support)
56,000 Btu/Hr (actual amount of
Btu/Hr used)
The space in the above example is a conned space
because the actual Btu/Hr used is more than the maxi-
mum Btu/Hr the space can support. You must provide
additional fresh air. Your options are as follows:
30,000
26,000
56,000
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