Combustion And Ventilation Air - Raypak 751 Installation And Operating Instructions Manual

Fig. 2: Minimum Clearances from Combustible
Surfaces
Outdoor Installations
Raypak Advanced Design Boilers are design certified
by CSA for outdoor installation. Roof water drainage
must be diverted away from boilers installed under
overhangs.
Heater Side
Rear
Right
Left
Top
Vent
Table C: Clearances – Outdoor Installations
WARNING: Combustion air inlet (blower air inlet)
should have 6" minimum clearance from any
obstruction, i.e. walls or other appliances.
Min. Clearance from
Combustible Surfaces
12" (water side)
36"
36"
0"
1"

Combustion and Ventilation Air

Indoor Units
The boiler 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 venting, where combustion air is
drawn from the area immediately surrounding the boil-
er, or via direct vent, where combustion air is drawn
directly from outside. All installations must comply with
the requirements of NFGC for U.S., CSA B149 for
Canada, and all local codes.
NOTE: In calculating free area, the required size of
openings for combustion, ventilation, and dilution air
shall be based on net free area of each opening. If
the free area through a design of louver or grill is
known, it shall be used in calculating the size
opening required to provide the free area specified.
For additional information, refer to the latest NFGC
code requirements.
Direct Vent
If outside air is drawn through a vent pipe directly to
the unit for combustion:
1. Install combustion air direct vent in accordance
with the Venting section of this manual.
2. Provide for adequate ventilation of the space
occupied by the boiler(s) by an opening(s) for ven-
tilation air at the highest practical point
communicating with the outdoors. The total cross
sectional area shall be at least one (1) square inch
of free area per 20,000 BTUH of total input rating
of all equipment in the room when the opening is
communicating directly with the outdoors or
through vertical duct(s). The total cross sectional
area shall be at least one (1) square inch of free
area per 10,000 BTUH of total input rating of all
equipment in the room when the opening is com-
municating 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 boiler during the
non-operating hours.
CAUTION: Remove the screen off the blower inlet
and install a screen (1/2"-3/4" mesh) on the inlet
elbow.
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