Setting Gas Pressure - Goodman GRL SERIES Installation Instructions Manual

ORIFICE ORDERING
INFORMATION
Orifice sizes are selected by adding
the 2-digit drill size required in the
orifice part number. Drill sizes
available are 39 through 64; metric
sizes available 1.10mm (-90) and
1.15mm (-91):
Orifice Part Number 62-22175-(drill
size)
Example 1:
# 60 drill size orifice required
Part # 62-22175-60
Example 2:
1.15mm drill size orifice required
Part # 62-22175-91
NOTE: Do not plug or drill out orifices.
TABLE 4
BTU Input (per
Altitude burner) 15000
0 to 2000 ft. 15000
2000'-3000' 13200
3000'-4000' 12600
4000'-5000' 12000
5000'-6000' 11400
6000'-7000' 10800
7000'-8000' 10200
8000'-9000' 9600
9000'-10000' 9000

SETTING GAS PRESSURE

The maximum gas supply pressure
to the furnace should be 10.5" w.c.
natural gas, or 13" w.c. LP gas. The
minimum supply gas pressure to the
gas valve should be 5" w.c. natural
gas or 11" w.c. LP gas. A properly
calibrated U-Tube manometer is
required for accurate gas pressure
measurements.
CAUTION
!
ELEVATIONS ABOVE 2000 FT
REQUIRE THAT THE FURNACE
INPUT RATING BE ADJUSTED AND
THAT THE SIZE OF THE BURNER
ORIFICES BE RE-CALCULATED
BASED ON ELEVATION AND GAS
HEATING VALUE. THE BURNER
ORIFICES MAY (OR MAY NOT)
NEED TO BE CHANGED. SEE THE
SECTION TITLED "HIGH ALTITUDE
INSTALLATIONS" OF THIS BOOK
FOR INSTRUCTIONS.
30
Supply Gas Pressure Measure-
ment. A line pressure tap is on the
input side of the gas valve. See Figure
26.
1. With gas shut off to the furnace at
the manual gas stop outside the
unit, remove the input pressure
tap plug.
2. Connect a U-Tube manometer to
the pressure tap.
3. Turn on the gas supply and
operate the furnace and all other
gas-fired units on the same gas
line as the furnace.
4. Note or adjust the line gas
pressure to give:
A. 5" - 10.5" w.c. for natural gas.
B. 11" - 13" w.c. for LP gas.
5. Shut off the gas at the manual
gas stop and remove the
U-Tube manometer.
6. Replace the pressure tap plug
Orifice
before turning on the gas. Turn
Size
on gas and check for leaks.
1.15 mm
If the supply gas line pressure is
(factory)
above these ranges, install an in-line
1.15 mm
gas regulator to the furnace for natural
1.10 mm
gas units. With LP gas, have the LP
supplier reduce the line pressure at
#58
the regulator.
#59
If supply gas line pressure is below
#60
these ranges, either remove any
#62
restrictions in the gas supply piping or
#63 enlarge the gas pipe. See Tables 3
and 8. With LP gas, have the LP
#64
supplier adjust the line pressure at the
regulator.
FIGURE 25
MANIFOLD PRESSURE TAP
Manifold Gas Pressure
Measurement. Natural gas
manifold pressure should be 3.5"
w.c.; LP gas manifold pressure
should be 10" w.c. Only small
variations on gas pressure should be
made by adjusting the pressure
regulator.
1. With the gas shut off at the
manual gas stop, remove the
pressure tap plug in the gas
manifold or the gas valve outlet.
See Figure 26.
2. Connect a U-Tube manometer to
this pressure tap. See Figure 28.
3. Turn on the gas supply and
operate the furnace in high heat
mode.
4. Note or adjust the manifold gas
pressure to give:
A. 3.5" w.c. for natural gas high
fire.
B. 10" w.c. for LP gas high fire.
5. To adjust the pressure regulator
for high fire, remove the regulator
cap located on the side of the
regulator. See Figure 20.
6. Turn the adjustment screw
clockwise to increasre pressure
or counterclockwise to decrease
pressure.
7. Securely replace the regulator
cap for high fire.
8. Operate the furnace in low
speed.
MANIFOLD
PRESSURE
TAP