AAON M2-036 - Manual (Page 58)

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minimize the number of elbows or turns in
vent pipe.
Gas Supply, Piping and Connections
Gas piping must be installed in accordance
with local codes, or in the absence of local
code, installation must conform to the
current (United States) National Fuel Gas
Code ANSI-Z223.1/NFPA 54 or the current
(Canada) National Fuel & Propane
Installation Code CSA B149.1 or B149.2.
1. Gas piping must be sized for the total Btu
input of all units (heaters) serviced by a
single supply.
2. Be sure that gas regulators servicing more
than one heater have the proper pipe and
internal orifice size for the total input of all
heaters serviced by the regulator.
3. Duct furnaces require a minimum inlet
gas pressure of 5.0 “w.c and limited to a
maximum inlet gas pressure of 13.5” w.c.,
with the furnace operating.
4. A 1/8” NPT tap is provided on the inlet
side of the gas valve to the heater. A fitting
suitable for connection to a pressure gauge
capable of measuring gas pressure should be
connected to each heater serviced by a
single regulator so that gas pressure at each
heater can be measured with all heaters in
operation.
5. A drip leg (sediment trap) and a manual
shut off valve must be provided immediately
upstream of the gas control on the heating
unit. To facilitate servicing of unit,
installation of a union is recommended.
Figure 21 - Sediment Trap
1. All field gas piping must be
pressure / leak tested prior to
operation. NEVER use an open flame
to check for leaks. Use a soap
solution or other leak detecting
solution for testing.
2. Gas pressure to appliance controls
must never exceed 13.5” w.c. (1/2
psi)
WARNING
1. When pressure testing at 1/2 psi or
less, close the manual shutoff valve
on the appliance before testing.
2. When pressure testing gas supply
line at 1/2 psi or higher, close manual
gas valve and disconnect heater from
supply line to be tested. Cap or plug
the supply line.
WARNING