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107902-01D
4
For more information, visit www.desatech.com
For more information, visit www.desatech.com
AIR FOR COMBUSTION AND
VENTILATION
WARNING: This heater shall not be installed in a
confined space or unusually tight construction un-
less provisions are provided for adequate combus-
tion and ventilation air. Read the following instruc-
tions to insure proper fresh air for this and other fuel-
burning appliances in your home.
Today’s homes are built more energy efficient than ever. New materi-
als, increased insulation, and new construction methods help reduce
heat loss in homes. Home owners weather strip and caulk around
windows and doors to keep the cold air out and the warm air in. During
heating months, home owners want their homes as airtight as possible.
While it is good to make your home energy efficient, your home
needs to breathe. Fresh air must enter your home. All fuel-burning
appliances need fresh air for proper combustion and ventilation.
Exhaust fans, fireplaces, clothes dryers, and fuel burning appliances
draw air from the house to operate. You must provide adequate fresh
air for these appliances. This will insure proper venting of vented
fuel-burning appliances.
PROVIDING ADEQUATE VENTILATION
The following are excerpts from National Fuel Gas Code, ANSI
Z223.1/NFPA 54, Section 5.3, Air for Combustion and Ventilation.
All spaces in homes fall into one of the three following ventilation
classifications:
1. Unusually Tight Construction
2. Unconfined Space
3. Confined Space
The information on pages 4 and 5 will help you classify your space
and provide adequate ventilation.
Unusually Tight Construction
The air that leaks around doors and windows may provide enough
fresh air for combustion and ventilation. However, in buildings of
unusually tight construction, you must provide additional fresh air.
Unusually tight construction is defined as construction
where:
a. walls and ceilings exposed to the outside atmosphere
have a continuous water vapor retarder with a rating of
one perm (6 x 10
-11
kg per pa-sec-m
2
) or less with open-
ings gasketed or sealed
and
b. weather stripping has been added on openable windows
and doors
and
c. caulking or sealants are applied to areas such as joints
around window and door frames, between sole plates
and floors, between wall-ceiling joints, between wall pan-
els, 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 Out-
doors
, page 5
.
If your home does not meet all of the three criteria above,
proceed to
Determining Fresh-Air Flow For Heater Location
.
Confined and Unconfined Space
The National Fuel Gas Code, ANSI Z223.1/NFPA 54 defines a
confined 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 unconfined 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 communicating directly with the
space in which the appliances are installed*, through openings not
furnished with doors, are considered a part of the unconfined space.
* Adjoining rooms are communicating only if there are doorless
passageways or ventilation grills between them.
DETERMINING FRESH-AIR FLOW FOR
HEATER 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 heater plus any adjoining
rooms with doorless 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 22 ft. (length) x 18 ft. (width) x 8 ft. (ceiling
height) = 3168 cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with grills or open-
ings, 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 = (Maximum Btu/Hr the space
can support)
Example:
2560 cu. ft. (volume of space) x 20 = 51,200 (maximum
Btu/Hr the space can support)
AIR FOR COMBUSTION AND VENTILATION
Providing Adequate Ventilation
Determining Fresh-Air Flow For Heater Location