Filter
Top Products
area per 20,000 BTUH (111 mm
2
per kW) of total
input rating of all equipment in the room when the
opening is communicating directly with the out-
doors or through vertical duct(s). The total
cross-sectional area shall be at least 1 in.
2
of free
area per 10,000 BTUH (222 mm
2
per kW) of total
input rating of all equipment in the room when the
opening is communicating with the outdoors
through horizontal duct(s).
3. In cold climates, and to mitigate potential freeze-
up, Raypak highly recommends the installation of
a motorized sealed damper to prevent the circula-
tion of cold air through the heater during
non-operating hours.
Conventional Combustion Air
Supply
U.S. Installations
All Air from Inside the Building
The confined space shall be provided with TWO per-
manent openings communicating directly with an
additional room(s) of sufficient volume so that the com-
bined volume of all spaces meets the criteria for an
unconfined space. The total input of all gas utilization
equipment installed in the combined space shall be
considered in making this determination. Each open-
ing shall have a minimum free area of 1 in.
2
per 1,000
BTUH (22 cm² per kW) of the total input rating of all
gas utilization equipment in the confined space, but
not less than 100 in.² (645 cm²). One opening shall
commence within 6-3/4 in. of the top, and one opening
shall commence within 6-3/4 in. of the bottom, of the
enclosure. The minimum dimension of air openings
shall be not less than 3 in. (8 cm) in any direction.
All Air from Outdoors
The confined space shall communicate with the out-
doors in accordance with methods 1 or 2 below. The
minimum dimension of air openings shall not be less
than 3 in. (8 cm) in any direction. Where ducts are
used, they shall be of the same cross-sectional area
as the free area of the openings to which they connect.
1. Two permanent openings, one commencing
within 12 in. (30 cm) of the top, and one commenc-
ing within 12 in. (30 cm) of the bottom, of the
enclosure shall be provided. The openings shall
communicate directly, or by ducts, with the out-
doors or spaces (crawl or attic) that freely
communicate with the outdoors.
Combustion and Ventilation Air
Combustion Air Filter
This heater is supplied with an integral combustion air
filter. This filter will reduce the amount of particulates
passed through the combustion system and heat
exchanger but will not protect against chemical inside
air contamination (See Appendix). The filter must be
checked periodically to verify that adequate combus-
tion air is being supplied to the heater. See the
Maintenance section of this manual for information on
checking the filter and establishing service intervals.
Indoor Units
The heater must be supplied with sufficient quantities
of non-contaminated air to support proper combustion
and equipment ventilation. Combustion air can be sup-
plied via conventional means where combustion air is
drawn from the area immediately surrounding the
heater, or via direct vent, where combustion air is
drawn directly from outside. All installations must com-
ply with the requirements of the NFGC (U.S.) and
B149 (Canada), and all local codes.
Direct Combustion Air
If outside air is drawn through the intake pipe directly
to the unit for combustion:
1. Install combustion air direct vent in accordance
with the venting section of this manual.
2. Provide adequate ventilation of the space occu-
pied by the heater(s) by an opening(s) for
ventilation air at the highest practical point com-
municating with the outdoors. The total
cross-sectional area shall be at least 1 in.
2
of free
CAUTION: Combustion air must not be
contaminated by corrosive chemical fumes which
can damage the heater and void the warranty. (See
the Appendix.)
These clearances are required when the outdoor
vent cap is used. If installing the heater outdoors
with a vent stack, the indoor clearances may be
utilized.
The combustion air intake hood MUST be used for
outdoor installations. The hood is shipped loose and
installed on the side of the heater over the filter box at
the job site.
11