Procom FBD400RTCC-M-HC/MO Owner's Operation And Installation Manual page 8

AIR FOR COMBUSTION AND VENTILATION
The air that leaks around doors and windows
may provide enough fresh air for combustion
and ventilation. However, in buildings of un-
usually 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 kg per pa-sec-m
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openings gasketed or sealed and
b. weather stripping has been added on
openable windows and doors and
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/hr (4.8 m
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/hr (4.8 m
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 20 ft. (6.1 m)
(length) x 16 ft. (4.88 m) (width) x
8 ft. (2.44 m) (ceiling height) = 2560 cu.
ft. (72.49 m ) (volume of space)
3
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 deter-
mine the maximum Btu/Hr the space can
support.
________(volume of space) x 20 =
(Maximum Btu/Hr the space can support)
Example: 2560 cu. ft. (72.49 m
of space) x 20 = 51,200 (maximum Btu/
Hr the space can support)
8
Unusually Tight Construction
) or less with
2
Confined and Unconfined Space
per kw) of the aggregate
3
per kw) of the aggregate
3
) (volume
3
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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
panels, at penetrations for plumbing, elec-
trical and gas lines and at other openings.
If your home meets all of these three criteria,
you must provide additional fresh air. See
Ventilation Air From Outdoors, page 9.
If your home does not meet all of the three
criteria above, proceed to Determining Fresh-
Air Flow For Heater Location.
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.
3. Add the Btu/Hr of all fuel burning appli-
ances 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 appli-
ances. 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)
Example: 51,200 Btu/Hr (maximum the
space can support)
56,000 Btu/Hr (actual amount
of Btu/Hr used)
_________ Btu/Hr
_________ Btu/Hr
_________ Btu/Hr
_________ Btu/Hr
_________ Btu/Hr
= ________ Btu/Hr
30,000
__________ Btu/Hr
26,000
+ _________ Btu/Hr
56,000
= _________ Btu/Hr
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