Daikin DCG Series Installation And Maintenance Manual page 18

T
O AVOID PROPERTY DAMAGE
FIRE GAS UNIT WITH FLUE BOX COVER REMOVED
NOTE: Except during brief periods when gas pressures are being
measured by qualified service personnel, the furnace access panel
must always be secured in place when the furnace is in operation.
An inspection port in the access panel is provided to monitor the
flame.
The first step in checking out the gas-fired furnace is to test the
gas supply piping to the unit for tightness and purge the system of
air using methods outlined in the latest edition of the National
Fuel Gas Code ANSI Z223.1. Verify that the disconnect switch is in
the "OFF" position. A soapy water solution should be used to check
for gas leaks. Since the unit is subject to considerable jarring dur-
ing shipment, it is extremely important that all gas connections
and joints be tested for tightness. Gas piping downstream from
the unit inlet should be checked for leaks during the subsequent
sequence check.
The supply gas pressure should be adjusted to 7.0" w.c. on natural
gas and 11.0" on LP gas with the gas burners operating. If there is
more than one unit on a common gas line, the pressures should
be checked with all units under full fire. A supply pressure tap is
provided on the upstream side of the gas valve. A manifold pres-
sure tap is provided on the manifold. The normal manifold pres-
sure for full input is 3.5" w.c. on natural gas and 10.0" w.c. for
propane gas. Minimum gas supply pressure is 5.5" w.c. for natural
gas and 11.0" for propane gas. In order to obtain rating, gas supply
pressure must be 11.0" w.c. for propane gas.
The pressure regulator on LP gas models is adjusted for 10.0" w.c.
manifold pressure and is intended to prevent over-firing only. Do
not attempt adjustment of the built-in pressure regulator unless
the supply pressure is at least 7.0" w.c. on natural gas or 14.0" w.c.
on propane gas. Check the location of the ignition electrode and
the flame sensor for correct gap setting.
Ignitor
WARNING
, ,
PERSONAL INJURY OR DEATH DO NOT
.
MAXIMUM NUMBER
INPUT
(BTUH) BURNERS
350,000
400,000
HEAT EXCHANGER AND BURNER ORIFICE SPECIFICATIONS
NOTE: Gas appliances located more than 2000 feet above sea level
must be derated 4% per 1000 feet of total elevation and that
variance in gas heating value and specific gravity require change
in manifold pressure to obtain rating, it is mandatory that the input
be adjusted at the installation site. All installations should be made
as outlined in the latest edition of the National Fuel Gas Code ANSI
Z223.1, section "Procedures To Be Followed To Place An Appliance
in Operation". Refer also to the "User's Information Manual"
supplied with the unit for additional information on the gas furnace.
Gas Supply And Manifold Check
Gas supply pressure and manifold pressure with the burners oper-
ating must be as specified on the rating plate.
Gas Inlet Pressure Check
Gas inlet pressure must be checked and adjusted in accordance to
the type of fuel being consumed.
With Power And Gas Off:
1. Connect a water manometer or adequate gauge to the
inlet pressure tap of the gas valve.
Inlet gas pressure can also be measured by removing the
cap from the dripleg and installing a predrilled cap with a
hose fitting.
With Power And Gas On:
2. Put unit into heating cycle and turn on all other gas
consuming appliances.
NATURAL
PROPANE
NOTE: Inlet Gas Pressure Must Not Exceed the Maximum Value
Shown.
If operating pressures differ from above, make necessary pressure
regulator adjustments, check piping size, etc., and/or consult with
local utility.
Manifold Pressure Check
The gas valve has a tapped opening to facilitate measurement of
the manifold pressure. A "U" Tube manometer having a scale range
from 0 to 12 inches of water should be used for this measure-
Flame
ment. The manifold pressure must be measured with the burners
Sensor
operating.
16
MAXIMUM
of
BTUH/BURNER
NATURAL
7 50,000 #30
8 50,000 #30
INLET GAS PRESSURE
Min. 5.0" W.C., Max. 10.0" W.C.
Min. 11.0" W.C., Max. 14.0" W.C.
GAS ORIFICES
PROPANE (LP)
#48
#48