11
Combustion And Ventilation Air
(Indoor Units Only)
The heater must have both combustion and ventilation air.
Minimum requirements for net free air supply openings
are one opening that is 12" (305 mm) from the ceiling for
ventilation, and one opening that is 12" (305 mm) from the
floor for combustion air as outlined in the latest edition of
the National Fuel Gas Code, ANSI Z223.1(Canada-CAN/
CSA-B149) and any local codes that may have jurisdiction.
All Air from Inside the Building:
Each opening shall have a minimum net free area as
noted:
Sq. in. (m²)
399 (0.26 m²)
Table F. Opening Minimum Net Free Requirements -
Indoor Air
All Air from Outdoors:
When air is supplied directly from outside the building, each
opening shall have a minimum net free area as noted:
Unrestricted
Opening
sq. in. (m
²
)
Typical Screened or
Louvered Opening
sq. in. (m
²
)
Typical Screened and
Louvered Opening
sq. in. (m
²
)
100 (0.06)
150 (0.1)
200 (0.13)
Table G. Opening Minimum Net Free Requirements -
Outdoor Air
CAUTION:
Combustion air must not be contaminated
by corrosive chemical fumes which can damage the
heater. Such damage will not be covered by the warranty
Direct Vent and Ducted
Combustion Air Systems
If outside air is drawn through the intake pipe directly to
the unit for combustion:
1.
Install combustion air direct vent as instructed by
"Direct Vent – Horizontal Through-the-Wall" on page
16 or "Direct Vent – Vertical" on page 17 of this
manual.
2.
Provide adequate ventilation of the space occupied
by the heater(s) by an opening(s) for ventilation air
at the highest practical point communicating with the
outdoors.
a.
In the US, the total cross-sectional area shall be
at least 1 in² of free area per 20,000 BTUH (111
mm² per kW) 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 1 in² of free area per 10,000 BTUH (222
mm² per kW) of total input rating of all equipment
in the room when the opening is communicating
with the outdoors through horizontal duct(s).
b. In Canada, there shall be permanent air supply
opening(s) having a total cross-sectional area of
not less than 1 in.² of free area per 30,000 BTUH
(70 mm² per kW) of the total rated input. The
location of the opening(s) shall not interfere with
the intended purpose of the opening(s) for the
ventilation air.
3.
Damper (by others) to prevent the circulation of cold
air through the heater during the
non-operating hours.
Venting
CAUTION:
Proper installation of flue venting is critical
for the safe and efficient operation of the heater.
General
Appliance Categories
Heaters are divided into four categories based on the
pressure produced in the exhaust and the likelihood of
condensate production in the vent.
Category I
– A heater which operates with a non-positive
vent static pressure and with a vent gas temperature that
avoids excessive condensate production in the vent.
Category II
– A heater which operates with a non-positive
vent static pressure and with a vent gas temperature that
may cause excessive condensate production in the vent.
Category III
– A heater which operates with a positive
vent pressure and with a vent gas temperature that avoids
excessive condensate production in the vent.
Category IV
– A heater which operates with a positive vent
pressure and with a vent gas temperature that may cause
excessive condensate production in the vent.
See the table
Table H
for appliance category requirements.
NOTE:
For additional information on appliance
categorization, see appropriate ANSI Z21 Standard
and the NFGC (U.S.), or B149 (Canada), or applicable
provisions of local building codes.
A
WARNING:
Contact the manufacturer of the vent
material if there is any question about the appliance
categorization and suitability of a vent material for
application on a Category IV vent system. Using improper
venting materials can result in personal injury, death or
property damage.
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UNCONTROLLED DOCUMENT IF PRINTED
Summary of Contents for Raypak X94 SR-410
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