Daikin DBG Series, Инструкция по эксплуатации

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SYSTEM OPERATION
15
Roof Top Location and Installation
The gas supply piping location and installation for roof top units
must be in accordance with local codes or, in the absence
of locals codes, with ordinances of the latest edition of the
National 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 servicing.
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 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 characteris-
tics, 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 Spec Sheet 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 connec-
tion 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 com -
bustion 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
Ductwork
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.
VENTING
NOTE: Venting is self-contained.
CONDENSATE DRAIN CONNECTION
Condensate Drain Connection
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 condensate piping. An external trap must be installed for
proper condensate drainage.