Checking Gas Pressure - Daikin DCG Series Service Instructions Manual

SERVICING
The length of Dimension "A" determines the angle of Gas
Stream Defraction, "B".
A dent or burr will cause severe deflection of gas stream.
No resizing should be attempted until all factors are taken
into consideration such as inlet manifold gas pressure,
alignment, and positioning, specific gravity and BTU content
of the gas being consumed.
The only time resizing is required is when a reduction in firing
rate is required for an increase in altitude.
Orifices should be treated with care in order to prevent
damage. They should be removed and installed with a box-
end wrench in order to prevent distortion. In no instance
should an orifice be peened over and redrilled. This will
change the angle or deflection of the vacuum effect or
entraining of primary air, which will make it difficult to adjust
the flame properly. This same problem can occur if an orifice
spud of a different length is substituted.
WARNING
Disconnect gas and electrical power supply.
1. Check orifice visually for distortion and/or burrs.
2. Check orifice size with orifice sizing drills.
3. If resizing is required, a new orifice of the same physical
size and angle with proper drill size opening should be
installed.
S-307 CHECKING GAS PRESSURE
Gas inlet and manifold pressures should be checked and
adjusted in accordance to the type of fuel being consumed.
WARNING
Disconnect gas and electrical power supply.
1. Connect a water manometer or adequate gauge to the
inlet pressure fitting of the gas valve.
2. Remove the pressure tap fitting at the manifold if provided
or check at the gas valve outlet fitting and connect
another manometer or gauge.
DENT OR
BURR
GAS
STREAM B
INLET (SUPPLY) PRESSURE MANOMETER
(FIELD SUPPLIED)
NOTE! SUPPLY PRESSURE
IS TO BE BETWEEN 5.0 & 7.0 INCHES NATURAL
AND 11.0 & 14.0 INCHES L.P. WITH THE FURNACE
OPERATING.
TWO-STAGE H VALVE
MEASURING INLET AND MANIFOLD GAS PRESSURE
With Power ON:
WARNING
Line Voltage now present.
3. Put unit into heating cycle and turn on all other gas
consuming appliances.
For NATURAL GAS:
a. Inlet pressure should be a nominal 7" w.c.
b. Manifold pressure for 2 stage heat models on low
stage should be
c. Manifold pressure for 2 stage heat models on
high stage should be 3.5" ± .3"w.c.
For PROPANE GAS:
a. Inlet pressure should be a nominal 11" w.c.
b. Manifold pressure for 2 stage heating models on
low stage should be 6" w.c.
c. Manifold pressure for 2 stage heat models on
high stage should be 10" w.c.
OUTLET (MANIFOLD)
PRESSURE MANOMETER
(FIELD SUPPLIED)
NOTE!
MANIFOLD PRESSURE
IS TO BE BETWEEN
3.2 & 3.7 NATURAL AND
10.0 & 11.0 INCHES L.P.
HIGH FIRE OR
SINGLE STAGE AND
BETWEEN
1.7 AND 2.3 INCHES
NATURAL
7.0 & 8.0 INCHES
LOW STAGE
2.0" w.c. ± .3"w.c.
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