Desa Vanguard VMH26TPC Owner's Operation And Installation Manual page 7

AIR FOR COMBUSTION
AND VENTILATION
Continued
Unusually tight construction is defined as
construction where:
a. walls and ceilings exposed to the out-
side atmosphere have a continuous
water vapor retarder with a rating of
one perm (6 x 10
or less with openings gasketed or
sealed and
b. weather stripping has been added on
openable windows and doors and
c. caulking or sealants are applied to ar-
eas such as joints around window and
door frames, between sole plates and
floors, between wall-ceiling joints, be-
tween wall panels, at penetrations for
plumbing, electrical, and gas lines, and
at other openings.
If your home meets all of the three criteria
above, you must provide additional fresh
air. See Ventilation Air From Outdoors ,
page 8.
If your home does not meet all of the three
criteria above, proceed to Determining
Fresh-Air Flow For Fireplace Location .
Confined and Unconfined Space
The National Fuel Gas Code, ANSI Z223.1.3/
NFPA 54 defines a confined space as a space whose
volume is less than 50 cubic feet per 1,000 Btu
3
per hour (4.8 m per kw) of the aggregate input
rating of all appliances installed in that space and
an unconfined space as a space whose volume is
not less than 50 cubic feet per 1,000 Btu per hour
3
(4.8 m per kw) of the aggregate input rating of all
appliances installed in that space. Rooms commu-
nicating directly with the space in which the ap-
pliances are installed*, through openings not fur-
nished with doors, are considered a part of the un-
confined space.
* Adjoining rooms are communicating only if there
are doorless passageways or ventilation grills be-
tween them.
113111-01B
-11
kg per pa-sec-m
www.desatech.com
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 doorless pas-
sageways or ventilation grills between the rooms.
2
)
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. (vol-
ume of space)
If additional ventilation to adjoining room is sup-
plied 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 fireplace
Gas water heater*
Gas furnace
Vented gas heater
Gas fireplace logs
Other gas appliances* + __________ Btu/Hr
Total
* 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
Vent-free fireplace ______________ Btu/Hr
Total
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 confined space
because the actual Btu/Hr used is more than the maxi-
mum Btu/Hr the space can support. You must pro-
vide additional fresh air. Your options are as follows:
__________ Btu/Hr
__________ Btu/Hr
__________ Btu/Hr
__________ Btu/Hr
__________ Btu/Hr
= __________ Btu/Hr
30,000
______________ Btu/Hr
+ 26,000
= 56,000
______________ Btu/Hr
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