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12
2. All units are furnished with standard female NPT pipe
connections. Connection pipe size is 3/4" NPT. 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 local 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 factory for
only one of these fuels. The fuels are NOT interchangeable.
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 14.0" 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 14.0" w.c..
6. All pipe connections should be sealed with a pipe thread
compound, which is resistant to the fuel used with the
furnace. A soapy water solution should be used to check
all joints for leaks. A 1/8" NPT plugged tap is located on
the entering side of the gas valve for test gauge connection
to measure supply (main) gas pressure. Another 1/8" tap
is provided on the side of the manifold 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
EXCESS
OF
1/2 PSIG (13.8”
W
.
C
.).
WARNING
T
HIS
UNIT
MUST
BE
ISOLATED
FROM
THE
GAS
SUPPLY
PIPING
SYSTEM
BY
CLOSING
ITS
INDIVIDUAL
MANUAL
SHUTOFF
VALVE
DURING
ANY
PRESSURE
TESTING
EQUAL
TO
OR
LESS
THAN
1/2 PSIG.
CAUTION
7. There must be no obstruction to prevent the flow of
combustion and ventilating air. A vent stack is not required
and must never be used. The power ventor 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 should be provided with an access panel large
enough to inspect the air chamber downstream of the heat ex-
changer. 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.
VENTING
NOTE: Venting is self-contained.
CONDENSATE DRAIN CONNECTION
C
ONDENSATE
D
RAIN
C
ONNECTION
A 1” female NPT drain connection is supplied on the side of the
unit and a 1” male NPT on the bottom of the drain pan for con-
densate piping. An external trap must be installed for proper con-
densate drainage.
UNIT
2" MINIMUM
FLEXIBLE
TUBING-HOSE
OR PIPE
3" MINIMUM
A POSITIVE LIQUID
SEAL IS REQUIRED
DRAIN CONNECTION
Install condensate drain trap as shown. Use 1" drain line and fit-
tings or larger. Do not operate without trap.
H
ORIZONTAL
D
RAIN
Drainage of condensate directly onto the roof may be acceptable;
refer to local code. It is recommended that a small drip pad of
either stone, mortar, wood or metal be provided to prevent any
possible damage to the roof.
C
LEANING
Due to the fact that drain pans in any air conditioning unit
will have some moisture in them, algae and fungus will
grow due to airborne bacteria and spores. Periodic clean-
ing is necessary to prevent this build-up from plugging the
drain.
Summary of Contents for DCG Series
Page 29: ...27 APPENDIX D WIRING DIAGRAMS...