Timing The Gas Meter - Goodman GMP Installation & Operating Instructions Manual

EXAMPLE:
Corrected input for a 100,000 Btu/hr. appliance installed at an altitude of 6.000 ft.
utilizing natural gas with a heating value of 1,000 Btu/ft
Corrected Input = 100,000 - (6,000 X .04) X (100,000 /
1,000)
Corrected Input = 100,000 - (240 X 100)
Corrected Input = 100,000 - 24,000
Corrected Input = 76,000
Using the orifices sized as shown in the table for 6,000 feet (#45), a meter time of
48.0 seconds is measured. The actual firing rate of the furnace is
Input = 1,000 (heating value of the gas) X 3600 (constant) / 48.0
3
ft of gas)
Input = 3,600,000 / 48.0
Input = 76,000 Btu/h
In Canada, the series and rating plate input for the furnace apply to installations up to 2,000 feet
(610m) above sea level. Kit HA-02 for natural and LP gases is required to convert furnaces from
elevations of 2,000 to 4,500 feet (610m to 1,370m). Canadian certification applies to the installa-
tions of up to 4,500 feet above sea level. Installations above 4,500 feet are subject to acceptance
by the local authorities having jurisdiction.
BEFORE ATTEMPTING ANY SERVICE OR ADJUSTMENTS - INSURE THAT THE GAS AND
ELCTRICAL SUPPLIES ARE OFF.
Use the following method to determine the firing rate of the furnace. The supply pressure tap
should be located on the field installed piping or gas shut-off valve, or on the combination gas
valve at the location marked "INLET PRESSURE TAP". The manifold pressure tap is located on
the combination gas valve in the furnace and labeled "OUTLET PRESSURE TAP".
• Install a manometer graduated in tenths of an inch of water column on the supply pressure tap
on the gas supply pipe.
• Remove plug at the "Manifold" pressure tap on the gas valve and install a second manometer.
• Determine the size of gas meter used.
• Shut off all other gas fired appliances except for the pilots.
• Place furnace in operation.
• Check the supply pressure regulator until the pressure shown on series and rating plate is ob-
tained. Adjust if necessary.
• After 15 minutes of operation, time the meter with a stop watch for 2 revolutions & divide by 2.
• Use the appropriate column to determine the furnace input.
• If necessary, adjust the manifold pressure at the gas valve by removing the regulator cap and
turning the adjustment screw clockwise to raise the pressure and counterclockwise to reduce
the pressure. The manifold pressure must be between 3.2" W.C. and 3.8" W.C. (3.5" nominal)
for natural gas and 9.5" W.C. to 10.5" W.C. for LP (a field conversion is necessary for LP). The
O137
WARNING

TIMING THE GAS METER

12
3
is determined by-
(meter time for 1