Goodman Mfg GDS8, GHS8, GMS8 instruction manual GAS Manifold Pressure Measurement and Adjustment

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.

WHITE-RODGERS 36F22 GAS VALVE

Only small variations in gas pressure should be made by adjusting 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.Connect a calibrated water manometer (or appropriate gas pressure gauge) at the gas valve outlet pressure tap (refer to gas valve figure in previous section).

3.Turn ON the gas supply and operate the furnace.

4.Measure gas manifold pressure with burners firing. Adjust manifold pressure according to the Manifold Gas Pressure table:

Manifold Gas Pressure

Ga s		Range	Nominal
Natural	3.2	- 3.8" w.c.	3.5" w.c.
Propane	9.7	- 10.3" w.c.	10.0" w.c.

6.Remove regulator screw cover. Turn regulator screw either clockwise to increase pressure or counterclockwise to decrease. Always adjust regulator to provide the correct pressure according to the original equipment manufacturer specifications listed on the appliance rating plate.

7.Replace regulator screw cover and finger-tighten securely.

8.Turn OFF all electrical power to the system.

9.Remove manometer and hose from outlet pressure tap.

10.Tighten outlet pressure tap clockwise 7 in-lbs minimum to seal port.

11.Turn ON system power and set thermostat to call for heat.

12.Using a leak detection solution or non-chlorine soap suds, check for leaks at hose connection. Bubbles forming indicate a leak. SHUT OFF GAS AND FIX ALL LEAKS IMMEDIATELY!

Measure gas manifold pressure with burners firing. Adjust manifold pressure per the Manifold Gas Pressure table.

Manifold Gas Pressure

Gas		Range	Nominal
Natural	3.2	- 3.8" w.c.	3.5" w.c.
Propane	9.7	- 10.3" w.c.	10.0" w.c.

The final manifold pressure must not vary more than ± 0.3 w.c. from specified manifold pressure.

Any necessary major changes in gas flow rate should be made by changing the size of the burner orifice.

GAS INPUT RATE MEASUREMENT (NATURAL GAS ONLY)

The final manifold pressure must not vary more than ± 0.3 “ w.c. The gas input rate to the furnace must never be greater than that

from the above specified pressures. Any necessary major changes			specified on the unit rating plate. To measure natural gas input
in gas flow rate should be made by changing the size of the burner			using the gas meter, use the following procedure.
orifice.			1.	Turn OFF the gas supply to all other gas-burning
5.	To adjust the gas valve pressure regulator, remove the
				appliances except the furnace.
	regulator cap.
			2.	While the furnace is operating, time and record one
6.	Turn the adjustment screw clockwise to increase the
				complete revolution of the smallest gas meter dial.
	pressure, or counterclockwise to decrease the pressure.
			3. Calculate the number of seconds per cubic foot (sec/ ft3) of
7.	Securely replace the regulator cap.
				gas being delivered to the furnace. If the dial is a one cubic
8.	Turn OFF gas to furnace at the manual shutoff valve and
				foot dial, divide the number of seconds recorded in step 2
	disconnect manometer.
				by one. If the dial is a two cubic foot dial, divide the number
9.	Reinstall gas valve outlet pressure tap plug before turning
				of seconds recorded in step 2 by two.
	on gas to furnace.		4. Calculate the furnace input in BTUs per hour (BTU/ hr).
WHITE-RODGERS 36G22 GAS VALVE
				Input equals the sum of the installation’s gas heating value
This valve is shipped from the factory with the regulator preset				and a conversion factor (hours to seconds) divided by the
				number of seconds per cubic foot. The measured input
(see control label).
				must not be greater than the input indicated on the unit
Consult the appliance rating plate to ensure burner manifold
				rating plate.
pressure is as specified.		If another outlet pressure is required,		EXAMPLE:
follow these steps.				Installation’s gas heating (HTG) value: 1,000 BTU/ft3
1.	Turn OFF all electrical power to the system.			(Obtained from gas supplier)
2.	Using a 3/32 inch hex wrench, loosen outlet pressure tap			Installation’s seconds per cubic foot: 34 sec/ ft3
	screw one turn. Do not remove screw.			Conversion Factor (hours to seconds): 3600 sec/hr
3.	Connect a calibrated water manometer and 5/16 inch hose			Input = (Htg. value x 3600) ÷ seconds per cubic foot
	to the gas valve outlet pressure tap. Hose should overlap			Input = (1,000 BTU/ft3 x 3600 sec/hr) ÷ 34 sec/ ft3
	tap by 3/8 inch.			Input = 106,000 BTU/hr
4.	Turn ON system power and set thermostat to a call for
				This measured input must not be greater than the input
	heat.
				indicated on the unit rating plate.
5.	Using a leak detection solution or non-chlorine soap suds,
			5. Turn ON gas and relight appliances turned off in step 1.
	check for leaks at hose connection. Bubbles forming
				Ensure all the appliances are functioning properly and that
	indicate a leak. SHUT OFF GAS AND FIX ALL LEAKS
				all pilot burners are operating.
	IMMEDIATELY!
IO-242C		24		05/05