Form I-VR (10-14), P/N 205202 R14, Page 31
Outside Combustion
Air Pipe Length Table
Combustion Air Inlet
Kit, Option DE2
If the air inlet terminal is located adjacent to the exhaust terminal, the terminals
must be separated by a minimum distance of three feet (.9M). The only excep
-
tion is when the air inlet is located directly below the horizontal vent cap. The
required clearance between an air inlet terminal located directly below the vent
cap is 18 inches (457mm) as illustrated in
FIGURE 27B
. See
FIGURES 26B
and 27B
in Paragraph 6.4.1 for illustrations and clearance requirements of an
air inlet terminal located adjacent to the heater vent terminal.
7.
Electrical and Wiring
All electrical wiring and connections, including electrical grounding MUST
be made in accordance with the National Electric Code NFPA No. 70 (latest
edition) or, in Canada, the Canadian Electrical Code, CSA Standard C22.1.
The installer should also be aware of any local ordinances or gas company
requirements that might apply. The heater must be electrically grounded and
connected to a separately fused circuit with a disconnect as required by the
National Electrical Code.
Check the rating plate on the heater for the supply voltage and current require
-
ments. A dedicated line voltage supply with disconnect switch should be run
1. Air from inside building
-- openings 1 square inch free area per 1000
BTUH. Never less than 100 square inches free area for each opening. See
(1) in
FIGURE 30
.
2. Air from outside through duct
-- openings 1 square inch free area per
2000 BTUH. See (2) in
FIGURE 30
.
3. Air direct from outside --
openings 1 square inch free area per 4000
BTUH. See (3) in
FIGURE 30
.
NOTE: For further details on supplying combustion air to confined space, see
National Fuel Gas Code Z223.1 (latest edition).
If directly piped outside combustion air is required
, use optional inlet air
kit, Option DE2. Follow the instructions included with the kit. The inlet air pipe
should be of a noncorroding material. The maximum length of the inlet air pipe
must not exceed the length shown in the Table below.
If the inlet air pipe passes through moisture-laden air, insulation or double-wall
tubing may be needed to prevent condensation on the outside of the pipe. Use
the combustion air inlet cap supplied with the option kit. A different type of com
-
bustion air inlet cap could cause nuisance problems and/or unsafe operating
conditions.
Maximum Length of Outside Combustion Air Inlet Pipe
Type of Inlet
Air Pipe
BTUH
Size
Hz
Maximum
Length
Equivalent Length for
90° Elbow
45° Elbow
* 4” Smooth Wall
50, 75, 100
50 or 60
80 ft (24.3M)
10 ft (3M)
5 ft (1.5M)
125
60 ft (18.3M)
10 ft (3M)
5 ft (1.5M)
150
60
5” Smooth Wall
150
50
175
50 or 60
200
60
* 4” Corrugated
or Flexible
50, 75, 100
50 or 60
40 ft (12.2M)
N/A
N/A
125
30 ft (9.1M)
N/A
N/A
150
60
5” Corrugated or
Flexible
150
50
175
50 or 60
200
60
*Assumes the use of three feet (.9M) of flexible pipe at the combustion air inlet on the burner/
control box
WARNING: If
you turn off or
disconnect the
electrical power
supply, turn off the
gas. See Hazard
Levels, page 2.