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3. Connect a calibrated water manometer and 5/16 inch
hose to the gas valve outlet pressure tap. Hose should
overlap tap by 3/8 inch.
3. Turn ON system power and set thermostat to a call for
heat.
4. 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!
5. Remove regulator screw cover. Turn regulator screw
either clockwise to increase pressure or counter-
clockwise to decrease. Always adjust regulator to
provide the correct pressure according to the original
equipment manufacturer specifications listed on the
appliance rating plate.
6. Replace regulator screw cover and finger-tighten se-
curely.
7. Turn OFF all electrical power to the system.
8. Remove manometer and hose from outlet pressure
tap.
9. Tighten outlet pressure tap clockwise 7 in-lbs mini-
mum to seal port.
10. Turn ON system power and set thermostat to call for
heat.
11. 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 using the table below.
Manifold Gas Pressure
Natural Gas
Propane Gas
The final manifold pressure must not vary more
than ± 1.0" w.c. from the natural gas or ± 2.0" w.c. from the
propane gas specified pressures.
Any necessary major changes in gas flow rate should be
made by changing the size of the burner orifice.
3.5" w.c.
10.0" w.c.
35
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 gas-burning
appliances except the furnace.
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/
ft
3
) 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/ft
(Obtained from gas supplier)
Installation's seconds per cubic foot: 34 sec/ ft
Conversion Factor (hours to seconds): 3600 sec/hr
Input = (Htg. value x 3600) ÷ seconds per cubic foot
Input = (1,000 BTU/ft
Input = 106,000 BTU/hr
Minor changes to the input rate may be accomplished
through manifold pressure adjustments at the gas valve.
Refer to Section XIV, Startup Procedure and Adjustment -
Gas Manifold Pressure Measurement and Adjustment for
details. NOTE: The final manifold pressure cannot vary by
more than ± 0.3" w.c. from the specified setting. Consult
your local gas supplier if additional input rate adjustment is
required.
5. Turn ON gas to and relight all other appliances turned
off in step 1. Be certain that all appliances are function-
ing properly and that all pilot burners are operating.
TEMPERATURE RISE
Temperature rise must be within the range specified on the
unit rating plate. An incorrect temperature rise may result in
condensing in or overheating of the heat exchanger. An
airflow and temperature rise table is provided in the speci-
fication sheet. Determine and adjust temperature rise as
follows:
1. Operate furnace with burners firing for approximately
ten minutes. Ensure all registers are open and all duct
dampers are in their final (fully or partially open) posi-
tion.
2. Place thermometers in the return and supply ducts as
close to the furnace as possible. Thermometers must
not be influenced by radiant heat by being able to "see"
the heat exchanger.
x 3600 sec/hr) ÷ 34 sec/ ft
3
3
3
3
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