Installation Guide

21
3. Outlet pressure tap connections:
a. White-Rodgers valve:
Back outlet pressure test screw (outlet pressure Tap) out
one turn (counterclockwise, not more than one turn).
4. Attach a hose and manometer to the outlet pressure Tap.
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 Tap. 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 following Manifold Gas
Pressure table.
Natural Gas 3.2" - 3.8" w.c.
Propane Gas 9.7" - 10.3" w.c.
Manifold Gas Pressure
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 Tap.
12. Replace outlet pressure tap:
a. White-Rodgers 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!
Replace regulator cover screw.
Range Nominal
Natural High Stage 3.2 - 3.8" w.c. 3.5" w.c.
Propane High Stage 9.7 - 10.3" w.c. 10.0" w.c.
Ma nifold Ga s P re ssure
Gas
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 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
This measured input must not be greater than the input
indicated on the unit rating plate.
5. Turn ON gas and relight appliances turned off in step 1.
Ensure all the appliances are functioning properly and that
all pilot burners are operating.
TEMPERATURE R ISE
Air temperature rise is the temperature difference between supply
and return air. The proper amount of temperature rise is usually
obtained when the unit is operated at the rated input with the “as
shipped” blower speed. If the correct amount of temperature rise
is not obtained, it may be necessary to change the blower speed.
An incorrect temperature rise can cause condensing in or
overheating of the heat exchanger. Determine and adjust the
temperature rise as follows. The temperature rise must be within
the range specified on the rating plate or Specification Sheet
applicable to your model. (Please contact your distributor or our
website for the applicable Specification Sheet referred to in this
manual.)
SUPPLY
AIR
RETURN
AIR
Temperature Rise Measurement
1. Operate furnace with burners firing approximately 15
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.
3. Subtract the return air temperature from the supply air
temperature to determine the air temperature rise. Allow
adequate time for thermometer readings to stabilize.