Carrier AERO 39MN Installation, Start-Up And Service Instructions Manual page 117

NOTE: See the section Vertically Vented
Duct Furnaces on page 113 for vent pipe
diameters.
(Only dedicated furnace venting permitted. Each furnace must have its own inidivdual vent pipe and terminal.)
GAS SUPPLY, PIPING, AND CONNECTIONS — Installa-
tion of piping must conform with local building codes and ordi-
nances, or in the absence of local codes with ANSI Z223.1, the
National Fuel Gas Code. In Canada, installation must be in ac-
cordance with CAN/CGA-B149.1 for natural gas and B149.2 for
propane units.
Use a pipe sealant resistant to LP gases on gas supply connec-
tions to heater. Gas piping must be sized for the total Btu input of
all furnaces or units serviced by a single supply.
Be sure that gas regulators servicing more than one heater
have the proper pipe and internal orifice size for the total input of
all heating units serviced by the regulator. See Fig. 100.
Individual duct furnaces require a minimum inlet gas pres-
sure as shown in Table 32.
Table 32 — Inlet Gas Pressures
MINIMUM (in. wg):
GAS
50,000 - 400,000
SUPPLY
Btuh MODELS
Natural
5.0
Gas
Propane
11.0
Gas
IMPORTANT: Gas pressure to appliance controls
must never exceed 13.5 in. wg (
The individual duct furnace inlet gas supply pipe connection
size is 3 / in. NPT for gas inputs up to 400,000 Btuh and 1 in.
4
NPT for gas inputs between 401,000 and 600,000 Btuh for all
control systems.
PRESSURE
REGULATOR
GAS
SUPPLY
AIR-HANDLING UNIT
Category III Horizontal Furnace Venting (through Sidewall)
Fig. 99 — Indoor Horizontal Venting
MINIMUM (in. wg):
401,000 AND MAXIMUM
HIGHER Btuh (in. wg)
MODELS
6.0 13.5
12.0 13.5
1 / psig).
2
MAX. 13.5" W.C.
Fig. 100 — Inlet Pressure for Multiple Heaters
5 FT. (1.52 M) MIN.
50 FT. (15.35 M) MAX. EQUIV. LENGTH
1/4 IN. (6 mm) PITCH PER
1 FT. (305 mm) HORIZONTAL
RUN
SEE VENT PIPE
DIAMETER TABLE
FOR
VENT DIAMETER
FIELD FABRICATED
VENT TO EACH
EXHAUST CONNECTION
CONDENSATE
DRAIN
The duct furnace gas piping was leak tested prior to shipping
the furnace. However, during shipping and installation connec-
tions may have loosened. Check for leaks using a soap solution
and correct any leaks before placing furnace in operation.
A drip leg (sediment trap) and a manual shut-off valve must
be provided immediately upstream of the gas control on the heat-
ing unit. To facilitate servicing of unit, installation of a union is
recommended. See Fig. 101.
Pressure Testing — Connect a fitting and pressure gauge suit-
able for measuring gas pressure to
the manual shut-off valve tapping (see Fig. 6) or the inlet side of
the gas valve (Fig. 102A-102C). For multiple heater installa-
tions, measure inlet pressure to each heater serviced by a single
regulator with all heaters in operation. See Fig. 100.
IMPORTANT: When pressure testing at
less, close the manual shut-off valve on the appliance
before testing. When pressure testing the gas supply
line at 1 / psig or greater, close the manual shut-off
2
valve and disconnect the heater from supply line to be
tested. Cap or plug the supply line.
All field gas piping must be pressure and leak-tested prior
to operation. Never use an open flame to check for leaks.
Use a soap solution or other leak detecting solution.
UNIT 1 UNIT 2
116
1 FT.
MIN.
LISTED VENT
TERMINAL
3 FT. MIN. (0.91 m) ABOVE
CONDENSATE
HIGHEST SNOWFALL
DRAIN
EXTERIOR WALL
/ in. NPT tap provided on
1
8
WARNING
MINIMUM INLET PRESSURE
REQUIRED AT LAST HEATER
UNIT 3
a39-4397
/ psig or
1
2
a39-4398