1.Turn OFF gas to furnace at the manual gas shutoff valve external to the furnace.
2.Connect a calibrated water manometer (or appropriate gas pressure gauge) at either the gas valve inlet pressure boss or the gas piping drip leg.
Gas Line
Gas
Shutoff
Valve
Gas Line
To Furnace
Open To
Atmosphere
Drip Leg Cap
With Fitting
Manometer Hose
Manometer
Measuring Inlet Gas Pressure (Alt. Method)
NOTE: If measuring gas pressure at the drip leg, a field supplied hose barb fitting must be installed prior to making the hose connection. If using the inlet pressure boss on the gas valve, then use the 36G Valve Pressure Check Kit, Goodman Part No. 0151K00000S.
3.Turn ON the gas supply and operate the furnace and all other gas consuming appliances on the same gas supply line.
4.Measure furnace gas supply pressure with burners firing. Supply pressure must be within the range specified in the Inlet Gas Supply Pressure table.
Inlet Gas Supply Pressure
Natural Gas | Minimum: 5.0" w.c. | Maximum:10.0" w.c. |
Propane Gas | Minimum: 11.0" w.c. | Maximum:13.0" w.c. |
If supply pressure differs from table, make the necessary adjust- ments to pressure regulator, gas piping size, etc., and/or consult with local gas utility.
5.Turn OFF gas to furnace at the manual shutoff valve and disconnect manometer. Reinstall plug before turning on gas to furnace.
6.Turn OFF any unnecessary gas appliances stated in step 3.
GAS MANIFOLD PRESSURE MEASUREMENT AND ADJUSTMENT
CAUTION
TO PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE, THE GAS MANIFOLD PRESSURE MUST BE AS SPECIFIED ON THE UNIT RATING PLATE. ONLY MINOR ADJUSTMENTS SHOULD BE MADE BY ADJUSTING THE GAS VALVE PRESSURE REGULATOR.
Only small variations in gas pressure should be made by adjust- ing the gas valve pressure regulator. The manifold pressure must be measured with the burners operating. To measure and adjust the manifold pressure, use the following procedure.
1.Turn OFF gas to furnace at the manual gas shutoff valve external to the furnace.
2.Turn off all electrical power to the system.
3.Back outlet pressure test screw (inlet/outlet pressure boss) out one turn (counterclockwise, not more than one turn).
4.Attach a hose and manometer to the outlet pressure boss of the valve.
5.Turn ON the gas supply.
6.Turn on power and energize main (M) solenoid. Do not energize the HI solenoid.
7.Measure gas manifold pressure with burners firing. Adjust manifold pressure using the Manifold Gas Pressure table shown below.
8.Remove regulator cover screw from the low (LO) outlet pressure regulator adjust tower and turn screw clockwise to increase pressure, or counterclockwise to decrease pressure.
9.Energize main (M) solenoid as well as the HI terminal.
10.Remove regulator cover screw from the HI outlet pressure regulator adjust tower and turn screw clockwise to increase pressure, or counterclockwise to decrease pressure.
11.Turn off all electrical power and gas supply to the system.
12.Remove manometer hose from outlet pressure boss.
13.Turn outlet pressure test screw in to seal pressure port (clockwise, 7
14.Turn on electrical power and gas supply to the system.
15.Turn on system power and energize valve.
16.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.
NOTE: For gas to gas conversion, consult your dealer for appropriate conversion.
| Manifold Gas Pressure |
| ||
| Gas | Range | Nom inal | |
Natural | Low Stage | 1.6 - 2.2" | w .c. | 1.9" w .c. |
| High Stage | 3.2 - 3.8" | w .c. | 3.5" w .c. |
Propane | Low Stage | 5.7 - 6.3" | w .c. | 6.0" w .c. |
| High Stage | 9.7 - 10.3" w .c. | 10.0" w .c. | |
GAS INPUT RATE MEASUREMENT (NATURAL GAS ONLY)
The gas input rate to the furnace must never be greater than that specified on the unit rating plate. To measure natural gas input using the gas meter, use the following procedure.
1.Turn OFF the gas supply to all other
2.While the furnace is operating, time and record one complete revolution of the smallest gas meter dial.
3.Calculate the number of seconds per cubic foot (sec/ft3) of gas being delivered to the furnace. If the dial is a one cubic foot dial, divide the number of seconds recorded in step 2 by one. If the dial is a two cubic foot dial, divide the number of seconds recorded in step 2 by two.
4.Calculate the furnace input in BTUs per hour (BTU/hr). Input equals the sum of the installation’s gas heating value and a conversion factor (hours to seconds) divided by the number of seconds per cubic foot. The measured input must not be greater than the input indicated on the unit rating plate.
EXAMPLE:
Installation’s gas heating (HTG) value: 1,000 BTU/ft3 (Obtained from gas supplier)
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