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Fuel Gas Code (ANSI Z223.1).
A manual gas shut off valve must be field installed external to
the roof top unit. In addition, a drip leg must be installed near
the inlet connection. A ground joint union connection is required
between the external shut off valve and the unit connection to
the gas valve to permit removal of the burner assembly for ser-
vicing.
1. Route gas piping to unit so that it does not interfere with
the removal of access panels. Support and align piping to
prevent strains or misalignment of the manifold assembly.
2. All units are furnished with standard female NPT pipe
connections. Connection pipe size is 1/2" NPT on 045
to 140 mBH units. The size of the gas supply piping to
the unit must be based on length of run, number of units
on the system, gas characteristics, BTU requirement
and available supply pressure. All piping must be done
in accordance with local codes or, in the absence of lo-
cal codes, with the latest edition of the National Fuel Gas
Code (ANSI Z223.1).
NOTE:
The gas connection size at the unit does NOT
establish the size of the supply line.
3. These units are designed for either natural or propane
(LP) gas and are specifically constructed at the facto-
ry for only one of these fuels. The fuels are NOT inter-
changeable. However, the furnace can be converted in
the field from natural gas to LP gas with the appropriate
factory kit (see unit Technical Manual for the appropriate
kit). Only a qualified contractor, experienced with natural
and propane gas systems, should attempt conversion. Kit
instructions must be followed closely to assure safe and
reliable unit operation.
4. With all units on a common line operating under full fire,
natural gas main supply pressure should be adjusted to
approximately 7.0" w.c., measured at the unit gas valve.
If the gas pressure at the unit is greater than 10.5" w.c.,
the contractor must furnish and install an external type
positive shut off service pressure regulator. The unit will
not function satisfactorily if supply gas pressure is less
than 5.5" w.c. or greater than 10.5" w.c..
NOTE:
A minimum horizontal distance of 48" between
the regulator and the furnace flue discharge is required.
5. With all units on a common line operating under full LP
gas main supply pressure should be at least 11.0" w.c.
and must be no greater than 13.0" w.c., measured at the
unit gas valve. Unit will not function satisfactorily if supply
gas pressure is less than 11.0" w.c. or greater than 13.0"
w.c..
6. All pipe connections should be sealed with a pipe thread
compound, which is resistant to the fuel used with the fur-
nace. A soapy water solution should be used to check all
joints for leaks. A tap is located on the entering side of the
gas valve for test gauge connection to measure supply
(main) gas pressure. Another tap is provided on the mani-
fold side of the gas valve for checking manifold pressure.
T
HIS UNIT AND ITS INDIVIDUAL SHUTOFF VALVE MUST BE
DISCONNECTED
FROM THE GAS SUPPLY SYSTEM DURING ANY
PRESSURE TESTING OF THAT SYSTEM AT TEST PRESSURES IN
1/2 PSIG (13.8"
EXCESS OF
T
ISOLATED
HIS UNIT MUST BE
SYSTEM BY CLOSING ITS INDIVIDUAL MANUAL SHUTOFF VALVE
DURING ANY PRESSURE TESTING EQUAL TO OR LESS THAN
PSIG.
7. There must be no obstruction to prevent the flow of com-
bustion and ventilating air. A vent stack is not required
and must never be used. The power venter will supply
an adequate amount of combustion air as long as the air
passageways are kept free of any obstructions and the
recommended external unit clearances are maintained.
CIRCULATING AIR AND FILTERS
d
uctwOrk
The supply duct from the unit through a wall may be installed
without clearance. However, minimum unit clearances must
be maintained (see "Clearances" section). The supply duct
should be provided with an access panel large enough to
inspect the air chamber downstream of the heat exchanger.
A cover should be tightly attached to prevent air leaks.
Ductwork dimensions are shown in the roof curb installation
manual.
If desired, supply and return duct connections to the unit
may be made with flexible connections to reduce possible
unit operating sound transmission.
NOTE: Venting is self-contained.
On some models, the inductor motor is a dual voltage motor.
It is factory wired for 230 volts. If field supply power is 208V,
the installer must swap the connections to the black and red
leads (located in the control box or burner compartment) to
ensure correct inductor motor operation.
CONDENSATE DRAIN CONNECTION
c
d
c
Ondensate
rain
A 3/4" female NPT drain connection is supplied on the end
of the condensate pan, with an alternate connection on the
bottom of the pan. An external trap must be installed for
proper condensate drainage.
13
WARNING
.
.).
W
C
CAUTION
FROM THE GAS SUPPLY PIPING
VENTING
OnnectiOn
1/2
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