Manual

31
HIGHVOLTAGE!
D ISCONNECT  ALL  POWER  BEFORE  SERVICING  OR 
INSTALLING  THIS  UNIT .M ULTIPLE  POWER  SOURCES  MAY 
BE  PRESENT .F AILURE  TO  DO  SO  MAY  CAUSE  PROPERTY 
DAMAGE , PERSONAL  INJURY  OR  DEATH .
WARNING
This valve is shipped from the factory with the regulator preset (see
control label).
Consult the appliance rating plate to ensure burner manifold pres-
sure is as specified. If another outlet pressure is required, follow
these steps.
1. Turn OFF gas to furnace at the manual gas shutoff valve
external to the furnace.
2. Turn OFF all electrical power to the system.
3. Outlet pressure tap connections:
a. Honeywell VR8215 valve:
Remove the outlet pressure boss plug. Install an 1/8”
NPT hose barb fitting into the outlet pressure tap.
b. White-Rodgers 36G22 valve:
Back outlet pressure test screw (outlet pressure boss)
out one turn (counterclockwise, not more than one turn).
4. Attach a hose and manometer to the outlet pressure barb
fitting (Honeywell valve) or outlet pressure boss (White-
Rodgers valve).
5. Turn ON the gas supply.
6. Turn ON power and close thermostat “R” and “W” contacts
to provide a call for heat.
7. Using a leak detection solution or soap suds, check for
leaks at outlet pressure boss plug (Honeywell valve) or
screw (White-Rodgers valve). Bubbles forming indicate a
leak. SHUT OFF GAS AND REPAIR ALL LEAKS
IMMEDIATELY!
8. Measure the gas manifold pressure with burners firing.
Adjust manifold pressure using the Manifold Gas Pressure
table shown below.
Manifold Gas Pressure
Natural Gas 3.5" w.c.
Propane Gas 10.0" w.c.
9. Remove regulator cover screw from the outlet pressure
regulator and turn screw clockwise to increase pressure or
counterclockwise to decrease pressure. Replace regulator
cover screw.
10. Turn OFF all electrical power and gas supply to the system.
11. Remove the manometer hose from the hose barb fitting or
outlet pressure boss.
12. Replace outlet pressure tap:
a. Honeywell VR8215 valve:
Remove the 1/8” NPT hose barb fitting from the outlet
pressure tap. Replace the outlet pressure boss plug and
seal with a high quality thread sealer.
b. White-Rodgers 36G22 valve: Turn outlet pressure test
screw in to seal pressure port (clockwise, 7 in-lb
minimum).
13. Turn ON electrical power and gas supply to the system.
14. Close thermostat contacts to provide a call for heat.
15. Retest for leaks. If bubbles form, SHUT OFF GAS AND
REPAIR ALL LEAKS IMMEDIATELY!
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 installation’s gas heating value multiplied by 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
3
(Obtained from gas supplier)
Installation’s seconds per cubic foot: 34 sec/ ft
3
Conversion Factor (hours to seconds): 3600 sec/hr
Input = (Htg. value x 3600) ÷ seconds per cubic foot
Input = (1,000 BTU/ft
3
x 3600 sec/hr) ÷ 34 sec/ ft
3
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 mani-
fold pressure cannot vary by more than ± 0.3” w.c. from the speci-
fied 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 functioning 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 condens-
ing in or overheating of the heat exchanger. An airflow and tem-
perature rise table is provided in the Specification Sheet applicable
to your model. 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) position.
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.