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UNVENTED PROPANE GAS LOG HEATER
DETERMINING 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
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 open-
ings, add the volume of these rooms to
the total volume of the space.
2. Divide the space volume by 50 cubic
feet to determine the maximum Btu/Hr
the space can support.
__________ (volume of space) ÷ 50
cu. ft. = (Maximum Btu/Hr the space
can support)
Example:
2560 cu. ft. (volume of
space) ÷ 50 cu. ft. = 51.2 or 51,200
(maximum Btu/Hr the space can sup-
port)
3. Add the Btu/Hr of all fuel burning ap-
pliances 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
Example:
Gas water heater 40,000 Btu/Hr
Vent-free heater + 33,000 Btu/Hr
Total = 73,000 Btu/Hr
* Do not include direct-vent gas appli-
ances. Direct-vent draws combustion
air from the outdoors and vents to the
outdoors.
PROVIDING ADEQUATE
VENTILATION
The following is exerpts from National Fuel
Gas Code. NFPA 54/ANSI Z223.1, Section
5.3, Air for Combustion and Ventilation.
All spaces in homes fall into one of the three
following ventilation classifications:
1. Unusually Tight Contruction; 2. Uncon-
fined Space; 3. Confined Space.
The information on pages 4 and 5 will help
you classify your space and provide ad-
equate ventilation.
Confined and Unconfined Space
The National Fuel Gas Code (ANSIZ2123.1,
1992 Section 5.3) 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 in-
stalled*, 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 ventila-
tion grills between them.
AIR FOR
COMBUSTION AND
VENTILATION
Today’s homes are built more energy effi-
cient than ever. New materials, increased
insulation, and new construction methods
help reduce heat loss in homes. Home own-
ers 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 pos-
sible.
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 com-
bustion and ventilation.
Exhaust fans, fireplaces, clothes dryers, and
fuel burning appliances draw air from the
house to operate. You must provide ad-
equate fresh air for these appliances. This
will insure proper venting of vented fuel-
burning appliances.
Continued
WARNING: This heater shall
not be installed in a confined
space unless provisions are pro-
vided for adequate combustion
and ventilation air. Read the fol-
lowing instructions to insure
proper fresh air for this and other
fuel-burning appliances in your
home.
Unusually Tight Construction
The air that leaks around doors and win-
dows 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 de-
fined as construction where:
a. walls and ceilings exposed to the
outside atmosphere have a con-
tinuous 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, be-
tween sole plates and floors, be-
tween wall-ceiling joints, be-
tween wall panels, at penetra-
tions for plumbing, electrical, and
gas lines, and at other openings.
If your home meets all of the three
criteria above, you must provide ad-
ditional fresh air. See
Ventilation Air
From Outdoors
, page 5
.
If your home does not meet all of the
three criteria above, proceed to
De-
termining Air Flow For Heater Loca-
tion
.