Armstrong World Industries 302, 243, 242 Service Reference Manual, AHALT390-1 High Altitude Kit

Service Reference Manual ACCESSORIES

7-15

AHALT390-1 High Altitude Kit

The AHALT390-1 kit contains the following parts to convert the 26, 38, 51 and 64HW/HWC series units to high altitude for natural or propane gas. If the field conversion is for high altitude propane gas, be sure to install the appropriate gas valve conversion kit (see page 7-14).

TABLE 7-7	AHALT390-1 Parts List
	Part	Quantity
	Installation Instructions	1
High Altitude Conversion Plate		1
Air Shutter Adjustment Label		1
Burner Orifices #55 (Natural Gas)		3
Burner Orifices #54 (Natural Gas)		5
Burner Orifices #53 (Natural Gas)		6
Burner Orifices #65 (Propane Gas)		3
Burner Orifices #64 (Propane Gas)		4
Burner Orifices #63 (Propane Gas)		6

Regulator - Natural Gas

The minimum permissible gas supply pressure is 5.0" W.C. for purpose of input adjustment. Gas input must never exceed the input capacity shown on the rating plate. The furnace is equipped for rated inputs with manifold pressure of 3.5" W.C. for natural gas. Only small variations in gas input may be made by adjusting the regulator. In no case should the final manifold pressure vary more than 0.3" W.C. from the specified pressure.

To check this pressure:

1.Turn off the gas valve.

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

3.Install a water manometer.

Turn gas valve “ON”. If manifold pressure must be adjusted, remove cap from pressure regulator and turn adjustment screw clockwise to increase pressure, counterclockwise to reduce pressure. After checking pressure, turn gas off, remove the manometer fitting and replace the pipe plug and regulator cap. Put furnace in operation and leak check plug for leaks using a soapy solution.

Check the furnace rate by observing the gas meter, when available, making sure all other gas appliances are turned off. The test hand on the meter should be timed for at least one revolution. Note the number of seconds for one revolution.

SRM-HW/HWC 8/99