18
441 01 2613 05
Specifications are subject to change without notice
Vent dampers on any appliance connected to the common vent
can cause condensation and corrosion in the venting system. Do
not use vent dampers on appliances common vented with this
furnace.
8. Gas Supply and Piping
CARBON MONOXIDE POISONING, FIRE AND
EXPLOSION HAZARD
Failure to follow this warning could result in
personal injury, death, and/or property damage.
Models designated for Natural Gas are to be used
with Natural Gas ONLY, unless properly converted to
use with Propane gas.
!
WARNING
Gas Supply Requirements
•
Use only the type of gas approved for this furnace. See rating
plate for approved gas type.
•
Gas input must not exceed the rated input shown on the rating
plate. Overfiring will result in failure of heat exchanger and
cause dangerous operation.
•
Do not allow minimum supply pressure to vary downward.
Doing so will decrease input to furnace. Refer to
Table 3
for
gas supply. Refer to
Table 6
and
Table 7
for manifold
pressures.
Table 3
Gas Pressures
Gas Type
Supply Pressure
Recommended
Max.
Min.
Natural
7 in wc
(1744 Pa)
14 in wc
(3487 Pa)
4.5 in wc
1121 Pa)
Propane
11 in wc
(2740 Pa)
14 in wc
(3487 Pa)
11 in wc
(2740 Pa)
Gas Piping Requirements
NOTE:
The gas supply line must be installed by a qualified service
technician in accordance with all building codes.
NOTE:
In the state of Massachusetts.
a. Gas supply connections MUST be performed by a
licensed plumber or gas fitter.
b. When flexible connectors are used, the maximum length
shall not exceed 36
″
(914.4mm).
c.
When lever handle type manual equipment shutoff
valves are used, they shall be T
!
handle valves.
d. The use of copper tubing for gas piping is NOT approved.
1. Install gas piping in accordance with local codes, or in the
absence of local codes, the applicable national codes.
2. It is recommended that a manual equipment shutoff valve be
installed in the gas supply line outside the furnace. Locate
valve as close to the furnace as possible where it is readily
accessible. Refer to
Figure 12.
FIRE HAZARD
Failure to follow this warning could result in
personal injury or death.
Use wrench to hold furnace gas valve when turning
elbows and gas line to prevent damage to the gas
valve and furnace.
!
WARNING
ON
OFF
ON
OFF
Use elbows and 3
#
(76.2mm) pipe nipple to con
nect valve to piping when using right side gas
pipe entry.
* Union may be installed inside the cabinet when necessary because of clearances.
Drip Leg and Union, Union* should be outside the
cabinet. Manual shut-off valve MUST be upstream of
dripleg, union, and furnace.
Propane Low
pressure
switch.
25
!
24
!
86
3
#
(76.2mm)
pipe nipple
Manual shut-off
valve
Typical Gas Piping (N8MP)
Figure 12
Representative drawing only, some models may vary in appearance.
National Excelsior Company
www.excelsiorhvac.com
Subject to change without notice.
