Daikin DCG Series, Installation And Maintenance Manual

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17
To adjust the pressure regulator, remove the adjustment screw or
cover on the gas valve. Turn out (counterclockwise) to decrease
pressure, turn in (clockwise) to increase pressure. Only small varia-
tions in gas flow should be made by means of the pressure regula-
tor adjustment. In no case should the final manifold pressure vary
more than plus or minus 0.3 inches water column from the speci-
fied nominal pressure. Any major changes in flow should be made
by changing the size of the burner orifices. The measured input
rate to the furnace must not exceed the rating specified on the
unit rating plate.
For natural gas, the manifold pressure must be between 3.2 and
3.8 inches w.c. (3.5 nominal) for high fire and between 1.7 and 2.3
inches w.c. (2.0 nominal) for low fire.
For propane gas, the manifold pressure must be between 9.7 and
10.3 inches w.c. (10.0 nominal) for high fire and between 6.7 and
7.3 inches w.c. (7.0 nominal) for low fire.
Gas Input (Natural Gas Only) Check
It is the responsibility of the contractor to adjust the gas input to
the unit.
To measure the gas input use a gas meter and proceed as
follows:
1. Turn off gas supply to all other appliances except the unit.
2. With the unit operating, time the smallest dial on the
meter for one complete revolution. If this is a 2 cubic foot
dial, divide the seconds by 2; if it is a 1 cubic foot dial, use
the seconds as is. This gives the seconds per cubic foot of
gas being delivered to the unit.
3. INPUT=GAS HTG VALUE x 3600 / SEC. PER CUBIC FOOT
Example: Natural gas with a heating value of 1000 BTU per cubic
foot and 34 seconds per cubic foot as determined by Step 2, then:
Input = 1000 x 3600 / 34 = 106,000 BTU per Hour. NOTE:
BTU content of the gas should be obtained from the gas
supplier. This measured input must not be greater than
shown on the unit rating plate.
Adjust input rate by varying the adjustment of the gas pressure
regulator on the gas valve. All adjustments must be made with
furnace operating at high fire and at normal operating tempera-
ture. A manometer should be connected to the gas valve to verify
pressure is within the specified range (see following figures for
manometer connections). Clockwise rotation of the pressure regu-
lator screw increases pressure and gas flow rate. Turn screw coun-
terclockwise to decrease pressure and gas flow rate. After adjust-
ment the furnace temperature rise must be within the range speci-
fied on the unit data plate. NOTE: Thermal efficiency of the fur-
nace is a product efficiency rating determined under continuous
operating conditions independent of any installed system.
Pressure Regulator
Adjustment
(Under Cap Screw)
Gas Valve
On/Off
Selector
Switch
INLET OUTLET
Inlet Pressure
Tap
Outlet Pressure
Tap
WHITE-RODGERS 36G22 - SINGLE STAGE
Inlet
Pressure Boss
Low Fire
Regulator Adjust
Manometer
Manometer
Hose
High Fire Regulator
Adjust
Regulator
Vent
Outlet
Pressure Boss
Open to
Atmosphere
WHITE-RODGERS 36G54 (2-STAGE) CONNECTED TO MANOMETER
PRESSURE ADJUSTMENTS
TO CONNECT MANOMETER TO GAS VALVE:
1. Back outlet pressure test screw (inlet/outlet pressure boss)
out one turn (counterclockwise, not more than one turn).
2. Attach a hose and manometer to the outlet pressure boss
of the valve.
TO REMOVE MANOMETER FROM GAS VALVE:
1. Remove manometer hose from outlet pressure boss.
2. Turn outlet pressure test screw in to seal pressure port
(clockwise, 7 in-lb. minimum).
3. Turn on electrical power and gas supply to the system.
4. Turn on system power and energize valve.
5. Using a leak detection solution or soap suds, check for
leaks at pressure boss screw. Bubbles forming indicate a
leak. SHUT OFF GAS AND FIX ALL LEAKS IMMEDIATELY.
T
O PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE
,
THE
GAS MANIFOLD PRESSURE MUST BE AS SPECIFIED ON THE UNIT
RATING PLATE
. O
NLY MINOR ADJUSTMENTS SHOULD BE MADE BY
ADJUSTING THE GAS VALVE PRESSURE REGULATOR
.
CAUTION