As Anifold Ressure; G I R M (N G O ); As Nput Ate Easurement; Measurement - Goodman *MVM96 Installation Instructions Manual

If supply pressure differs from table, make the necessary adjust-
ments to pressure regulator, gas piping size, etc., and/or consult
with local gas utility.
5. Turn OFF gas to furnace at the manual shutoff valve and
disconnect manometer. Reinstall threaded plug before
turning on gas to furnace.
6. Turn OFF any unnecessary gas appliances stated in step
3.
Gas Line
Gas
Shutoff
Valve
Drip Leg Cap
With Fitting
Manometer Hose
Measuring Inlet Gas Pressure (Alt. Method)
G M P
AS ANIFOLD RESSURE
T
O PREVENT UNRELIABLE OPERATION
GAS MANIFOLD PRESSURE MUST
. G
PLATE AS VALVE IS FACTORY
F . D
IELD ADJUSTMENT O NOT
The manifold pressure must be measured with the burners oper-
ating. To measure the manifold pressure, use the following pro-
cedure:
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: Remove the outlet
pressure tap plug. Install an 1/8" NPT hose barb fitting into
the outlet pressure tap. Refer to gas valve diagram on
preceding page.
4. Attach a hose and manometer to the outlet pressure barb
fitting.
5. Turn ON the gas supply.
6. Turn on power and close thermostat "R" and "W1" contacts
to provide a call for low stage heat.
7. Modulating furnaces light at 80% of max input. For
natural gas, the expected manifold pressure at ignition
will be in a range of 1.8" - 2.5" W.C. For LP gas, the
range will be 5.8" - 6.8" W.C.
NOTE: Measure the gas manifold pressure with the
burners firing. After every time the main power is turned
off and back on, the furnace will enter a calibration
Gas Line
To Furnace
Open To
Atmosphere
Manometer
M
EASUREMENT
CAUTION
OR EQUIPMENT DAMAGE
BE AS SPECIFIED ON THE UNIT
NOT
SET AND DOES REQUIRE ANY
.
ATTEMPT TO ADJUST VALVE
routine on the next call for heat The inducer will ramp
up and down during the calibration routine. After
calibration, the furnace will proceed to ignition cycle.
8. Field Test Mode is intended to help a service person
troubleshoot and check out an installed appliance by
bringing the furnace up to High fire (100% input), by-
passing the normal modulating routing.
To enter Field Test Mode the Fault Recall Push-Button
must be pressed twice within a 5 second period at any
time during a heating cycle, at which time the display
will show "Ft". While the display is showing "Ft",
pressing and holding the Fault Recall Push-Button for
3 seconds will enable the field test mode and override
the normal firing rate sequence at a rate of 100% for 5
minutes or until the end of the call for heat. The display
will show the normal "Hi" while the control is firing at
100%. If the Fault Recall Push-Button has not been
pressed within 5 seconds of displaying "Ft" the display
will revert back to normal.
NOTE: Gas valve is factory set and does NOT require
any field adjustment. Do NOT attempt to adjust valve.
9. Turn off all electrical power and gas supply to the system.
10. Remove the manometer hose from the hose barb fitting.
11. Remove the 1/8" NPT hose barb fitting from the outlet
pressure tap. Replace the outlet pressure tap plug and
seal with a high quality thread sealer.
12. Turn on electrical power and gas supply to the system.
13. Close thermostat contacts "R" and "W1/W2" to energize
the valve.
,
Using an approved liquid gas leak detector solution, check for
THE
leaks at outlet pressure tap plug. Bubbles forming indicate a leak.
RATING
SHUT OFF GAS AND REPAIR ALL LEAKS IMMEDIATELY!
Natural
Propane
G I R
AS NPUT
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 at high fire rate, time and
record one complete revolution of the smallest gas meter
dial.
3. Calculate the number of seconds per cubic foot (sec/ft
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
40
Manifold Gas Pressure
Gas
Range
High Stage 3.2 - 3.8" w.c.
High Stage 9.5 - 10.5" w.c.
M (N
ATE EASUREMENT ATURAL
Nominal
3.5" w.c.
10.0" w.c.
G O )
AS NLY
3
) of