Allied Air Enterprises 506271-01 Manifold Gas Pressure Adjustment Regulator Natural Gas

Manifold Gas Pressure Adjustment Regulator – Natural Gas

For purpose of input adjustment, the minimum permissible gas supply pressure is 5" w.c. for natural gas.

Gas input must never exceed the input capacity shown on the rating plate. The furnace is equipped for natural gas rated inputs with manifold pressure of 3.5" w.c.

The manifold pressure can be measured by shutting off the gas, removing the pipe plug in the downstream side of the gas valve, and connecting a water manometer or gauge.

Under no circumstances should the final manifold pressure vary more than 0.3" w.c. from the above specified pressures. To adjust the regulator, turn the adjusting screw on the regulator clockwise to increase pressure and input or counterclockwise to decrease pressure and input. See Figure 8 to assist in locating the regulator on the gas valve.

Check the furnace rate by observing the gas meter, making sure all other gas appliances are turned off. The test hand on the meter should be timed for at least one revolution, noting the number of seconds per revolution. The heating value of the gas can be obtained from the local utility.

Example: By actual measurement, it takes 38 seconds for

BTU/HR	=	Cubic Feet Per Revolution x 3600 x Heating
INPUT		# Seconds Per Revolution	Value

the hand on the 1-cubic foot dial to make a revolution with a 100,000 BTU/HR furnace running. The result is 99,750 BTU/ HR, which is close to the 100,000 BTU/HR rating of the furnace.

Manifold Gas Pressure Adjustment Regulator –

LPG/Propane Gas

LPG/propane units require a regulator, and a regulator on the LPG/propane tank is also required.

For purpose of input adjustment, the minimum permissible gas supply pressure (inlet side of gas valve) is 11" w.c. for LPG/propane.

If at any time ignition is slow and burner does not seem to be operating correctly, check manifold pressure (outlet side of the gas valve). It should be 10" to 10.5" w.c. pressure for LPG/propane.

The furnace is designed to obtain rated input at 10" w.c. manifold pressure for propane.

To check this pressure:

1.Turn off gas valve.

2.Remove plug on valve marked “OUTLET PRESSURE.”

3.Install a water manometer.

4.Turn on gas valve and initiate a call for heat. If manifold pressure must be adjusted, remove cap from pressure regulator and turn adjustment screw clockwise to increase pressure or counterclockwise to reduce pressure.

5.After checking pressure, turn gas off, remove manometer fitting, and replace pipe plug and regulator cap.

6.Put furnace in operation and check plug for leaks using soapy solution.

Burner and Burner Orifice Instructions

To check or change burners or burner orifices:

1.Close the main manual gas shutoff valve and turn off all power to unit.

2.Remove the burner access panel.

3.Disconnect the union in the gas supply line upstream of the gas valve and downstream of the manual shutoff valve.

4.Label wires going to the gas valve, then disconnect the wires.

5.To change orifice:

a.Remove 4 screws that fasten the manifold to the burner box assembly and remove the manifold.

b.Remove the orifices, then install replacement orifices.

c.To reassemble: Reverse above steps, making sure orifices are inserted into the orifice holders on the back end of the burners, and that burners are level and centered on each burner opening in the vest panel.

6.To remove or service burners:

a.Label and disconnect the wires to the rollout switch and disconnect the igniter and flame sensor leads at the ignition control.

b.Remove the 4 screws that secure the burner box assembly to the vest panel and remove the assembly from the unit.

c.Remove the 6 screws that fasten the burner rack and bottom shield assembly to the burner box. Burners are now accessible for removal.

d.To Reassemble: Reverse above steps.

506271-01 Issue 0921 Page 9 of 14