Goodman GCV9 Installation & Operating Instructions Manual - page 29
29
IO-243
6/04
Gas
Rate
Range
Nominal
High Stage 3.0 to 3.6" 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
Propane Gas
Natural Gas
5. For Natural Gas, adjust the gas valve manifold pressure
regulator as follows:
a. High Stage Manifold Pressure Adjustment
Remove the cap screw from the high stage manifold
pressure regulator.
Using an Allen wrench, adjust the high stage manifold
pressureregulator to the required pressure.
Reinstall cap screw and confirm high stage manifold
pressure.
b. Low Stage Manifold Pressure Adjustment
Remove the cap screw from the low stage manifold
pressure regulator.
Using an Allen wrench, adjust the low stage manifold
pressure regulator to the required pressure.
Reinstall cap screw and confirm low stage manifold
pressure.
6. For Propane Gas, adjust the gas valve manifold pressure
regulator as follows:
a. Remove the cap screw from the low stage manifold
pressure regulator.
b. Using an Allen wrench, increase low fire manifold pressure
by adjusting the low stage manifold regulator so the furnace
will light and carryover.
c. Remove the cap screw from the high stage manifold
pressure regulator adjustment location.
d. Using an Allen wrench, adjust the high stage manifold
pressure regulator to the required manifold pressure.
e. Reinstall the high stage manifold regulator cap screw.
Confirm high stage manifold pressure.
f.
Using an Allen wrench, adjust the low stage manifold
regulator, to obtain required manifold pressure.
g. Reinstall low stage manifold regulator cap. Confirm low
stage manifold pressure.
7. Turn OFF gas to furnace at the manual shutoff valve and
disconnect manometer.
8. Reinstall gas valve outlet pressure tap plug before turning on
gas to furnace.
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 us-
ing 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
Minor changes to the input rate may be accomplished through mani-
fold pressure adjustments at the gas valve. Refer to Section XIV,
Startup Procedure and Adjustment - Gas Manifold Pressure Mea-
surement 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 ad-
justment is required.
5. Repeat steps 2 through 4 on high stage.
6. 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.
T
EMPERATURE
R
ISE
Temperature rise must be within the range specified on the unit rat-
ing 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 Product Data Book 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.
RISE =
SUPPLY
AIR
RETURN
AIR
HEAT EXCHANGER
RADIATION "LINE OF SIGHT"
T
RETURN
T
SUPPLY
T
SUPPLY
-
T
RETURN
Temperature Rise Measurement
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 Section XIV, Startup Procedure and Adjustment -Circulator
Blower Speeds for speed changing details.