25
15. Turn on system power and energize valve.
16. Using a leak detection solution or soap suds, check for leaks
at pressure boss screw. Bubbles forming indicate a leak.
SHUT OFF GAS AND FIX ALL LEAKS IMMEDIATELY.
NOTE:
For gas to gas conversion, consult your dealer for
appropriate conversion.
Gas
Rate
Range
Nominal
High Stage
3.2 to 3.8" w.c.
3.5" w.c.
Low Stage
1.6 to 2.2" w.c.
1.9" w.c.
High Stage
9.7 to 10.3" w.c. 10.0" w.c.
Low Stage
5.7 to 6.3" w.c.
6.0" w.c.
Manifold Gas Pressure
Natural
Propane
G
AS
I
NPUT
R
ATE
M
EASUREMENT
(N
ATURAL
G
AS
O
NLY
)
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
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.
T
EMPERATURE
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 Product Data Book
applicable to your model*.
RISE =
SUPPLY
AIR
RETURN
AIR
HEAT EXCHANGER
RADIATION "LINE OF SIGHT"
T
RETURN
T
SUPPLY
T
SUPPLY
-
T
RETURN
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.
4. Adjust temperature rise by adjusting the circulator blower
speed. Increase blower speed to reduce temperature rise.
Decrease blower speed to increase temperature rise. Refer
to the following section for speed changing details.
C
IRCULATOR
B
LOWER
S
PEED
A
DJUSTMENT
WARNING
T
O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRICAL SHOCK, TURN
OFF
POWER TO THE FURNACE BEFORE CHANGING SPEED TAPS.
All furnaces are shipped with heating speed set at “B” and cooling
speed set at “D”. Use the following procedure to select the heating
and cooling speed needed for your unit.
Use the CFM LED (green), adjacent to the integrated control
module fuse to verify airflow quantity. The green CFM LED
blinks once for each 100 CFM of airflow.
1. Determine the tonnage of the cooling system installed with
the furnace. If the cooling capacity is in BTU/hr divide it by
12,000 to convert capacity to TONs.
Example:
Cooling Capacity of 30,000 BTU/hr.
30,000/12,000 = 2.5 Tons
2. Determine the proper air flow for the cooling system. Most
cooling systems are designed to work with air flows between
350 and 450 CFM per ton. Most manufacturers recommend
an air flow of about 400 CFM per ton.
Example:
2.5 tons X 400 CFM per ton = 1000 CFM
The cooling system manufacturer’s instructions must be checked
for required air flow. Any electronic air cleaners or other devices
may require specific air flows, consult installation instructions of
those devices for requirements.
