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Page 8

To change jumper positions, gently pull the jumper off the
pins and place it on the desired set of pins. The following
section outlines the different jumper selections available
and conditions associated with each one. Refer to figure 4
for identification.

After the CFM for each application has been determined,
the jumper settings must be adjusted to reflect those
given in the tables on page 2. Using the tables, determine
which row of CFM volumes most closely matches the
desired CFM. Once a specific row has been chosen
(NORMAL or –), CFM volumes from other rows cannot
be used. Below are the descriptions of each of the
jumper selections.

Refer to table 4 for factory settings. Refer to the tables on
page 2 for the approximate air volume for each setting.

TABLE 4

MODEL

NUMBER

G25MV3-60

G25MV3-75

VSP2–1 FACTORY SETTINGS

HIGH

LOW

HEAT

1

4

1

2

4

3

ADJUST

NORM

NORM

G25MV5-100

2

4

1

2

4

3

NORM

NORM

G25MV5-120

 

The 

ADJUST

 pins allow the motor to run at normal speed

or approximately 10% lower than normal speed. The
tables on page 2 give two rows (NORMAL and –) with
their respective CFM volumes. The + adjustment setting
is not operable. Notice that the normal adjustment
setting for heat speed position #3 is 2030 CFM (960
L/s). After the adjustment setting has been determined,
chose the remaining speed jumper settings from
those offered in the table.

The TEST pin is available to bypass the VSP2–1 control
and run the motor at approximately 70% to test that the
motor is operational. This is beneficial primarily in
troubleshooting. G must be energized for motor to run.

    

For G25MV units, place the 

   

jumper

across the second and third pins (position #2).

When W1 is energized, the 

jumper selections are

activated. The 

HEAT 

jumper selections are activated

when W2 is energized.

NOTE–In Harmony II zoning applications, HEATING
BLOWER jumper must be in position #2.

 

The 

HEAT

 jumper is used to set the blower speed to

obtain the required CFM as outlined in HEAT SPEED
section of the tables on page 2.

The 

HEAT

 jumper selections are activated with a call for

second-stage heating (W2).

IMPORTANT

Before changing jumper setting, make sure the
motor has completely stopped. Any jumper set-
ting change will not take place while the motor
is running.

 

The 

HIGH

 jumper is used to determine the CFM during

cooling speed. These jumper selections are activated
when G and DS terminals are energized.

 

The 

LOW

 jumper is used to determine CFM during low

speed cooling. These jumper selections are activated
when G is energized. The 

LOW

 jumper may also be used

for low speed heating. See the “HEAT” section for details.

  

Fan “OFF” timings (time that the blower operates after
the heat demand has been satisfied) are determined by
the arrangement of a jumper on the VSP2–1 board. See
figure 6. To adjust fan “OFF” timings, gently disconnect
the jumper and reposition it across pins corresponding
with the new timing. Fan “OFF” time is factory set at
270 seconds. The control has a non–adjustable, factory
preset “on” fan timing (45 seconds).

          
       

FIGURE 6

FAN-OFF TIME ADJUSTMENT

270

210

150

90

To adjust fan–off timings:

Remove jumper from VSP2–1 and

select one of the other pin com-
binations to achieve the desired

time.

TIMING

JUMPER

TIMING PINS (seconds)

Leave jumper off to achieve

330 second fan–off timing.

Fan-off timing is factory

set at 270 seconds

NOTE—If fan “OFF” time is too low, residual heat in
heat exchanger may cause primary limit S10 to trip
resulting in frequent cycling of blower. If this occurs,
adjust blower to longer time setting.

Table 5 outlines the operation of the variable speed
motor in relation to specific modes of operation. Some
information has been repeated from the previous section
to provide an example. Refer to each diagnostic LED or
jumper settings section for more information.

Summary of Contents for G25MV Series

Page 1: ...equipped with an electronic vari able speed VSM fan motor The VSM motor maintains a specified air volume throughout the entire external static range Units may be installed in upflow downflow or horizo...

Page 2: ...er is furnished with kit 2 in x 3 in 51 mm x 76 mm flue adaptor furnished with 60 input furnaces for connection to furnace induced draft blower 2 in x 4 in 51 mm x102 mm flue adaptor furnished with 75...

Page 3: ...LIMITS FRONT LOUVERED PANEL DOOR INTERLOCK SWITCH BURNER CONTROL BOARD TRANSFORMER PRESSURE SWITCHES NOx TURBULATOR VSP2 BOARD FLUE THERMOSTAT VARIABLE SPEED BLOWER MOTOR PRIMARY LIMIT G25MV BLOWER D...

Page 4: ...erating If the combustion air prove switch closes the combustion air blower continues to operate for 30 seconds pre purge before allowing ignition Pre purge allows the heat exchanger to be cleared of...

Page 5: ...Switch Open Failed to Prove Combustion Blower Operation or Blocked Vent Repair or Replace as Necessary Four Flashes Open Limit Check Primary Limit Rollout Switches and Secondary Limits Find source of...

Page 6: ...range The unit uses the VSP2 1 variable speed control board located on the blower access door which controls the blower speed and provides diagnostic LEDs The control has both a non adjustable factor...

Page 7: ...Ref V ICM2 reference voltage PIN 11 Heat Tap Heating blower speed programming PIN 12 C 24 VAC common PIN 13 cfm Motor speed diagnostic signal Diagnostic LED Lights ON OFF DS3 indicates there is a dem...

Page 8: ...mony II zoning applications HEATING BLOWER jumper must be in position 2 The HEAT jumper is used to set the blower speed to obtain the required CFM as outlined in HEAT SPEED section of the tables on pa...

Page 9: ...indicate the blower is operating NOTE In Harmony II zoning ap plications HTG BLOWER jumper must be in position 2 HARMONY ZONED APPLICATIONS The blower speed is controlled by the PWM pulse width modula...

Page 10: ...This allows for precise control of motor speed and allows the motor to compensate for varying load conditions as sensed by the controller In this case the controller monitors the static workload on th...

Page 11: ...s down Then the motor will immediately attempt a restart The shutdown feature provides protection in case of a frozen bearing or blocked blower wheel The motor may attempt to start eight times If the...

Page 12: ...oke Coil L13 A choke coil is used on all G25MV units The choke is located on the blower housing and is used to block radio frequency interference Precautions If the G25MV or its electronically control...

Page 13: ...auto reset switches which actuate on a temperature rise The switches are factory set and cannot be adjusted The 1 S21 limit shown on the top opens at 140 F 5 F 60 0 C 2 8 C on a temperature rise and...

Page 14: ...mit located on top of combustion air blower collector box see figure 15 The limit is a N C SPST auto reset limit which opens at 200 F 5 F 93 3 C 2 8 C on a temperature rise and closes at 160 F 8 F 71...

Page 15: ...same type valve must be used 24VAC terminals and gas control knob are located on top of the valve All terminals on the gas valve are connected to wires from the electronic burner control 24V applied t...

Page 16: ...to atmospheric pres sure If the flue becomes obstructed during operation and either switch senses a loss of negative pressure pressure becomes more equal with atmospheric pressure the switch opens th...

Page 17: ...anual shut off valve before pressure testing to isolate furnace from gas supply FIGURE 22 MANUAL MAIN SHUT OFF VALVE GAS VALVE WILL NOT HOLD TEST PRESSURE IN EXCESS OF 0 5 PSIG 14 W C GAS VALVE CAP GA...

Page 18: ...ered panel and disconnect the sensor wire from the flame sensor 2 Place meter in series between flame sensor and sensor wire Connect the positive lead of meter to the sensor wire and the negative lead...

Page 19: ...the return duct as above For systems with non ducted returns leave the other end of the manometer open to the atmosphere 3 With only the blower motor running and the evaporator coil dry observe the ma...

Page 20: ...lly clean piping thor oughly after leak detection has been completed Can cause damage to piping resulting in gas leaks fire or explosion C Supply Air Blower Check and clean blower wheel Motors are pre...

Page 21: ...5 The combustion air blower B6 is energized by A3 If the gas valve is energized on high fire then B6 is energized on high speed if the gas valve is energized on low fire then B6 is energized on low s...

Page 22: ...ANGED THROUGHOUT SEQUENCE THERMOSTAT CALLS FOR COOLING SYSTEM FAN SWITCHES TO HEATING SPEED AFTER SELECTED DELAY ACCA ACCH TERMINALS REMAIN ENERGIZED SYSTEM FAN SWITCHES TO CONTINUOUS SPEED AND ENERGI...

Page 23: ...OCKOUT MAIN VALVE OFF COMBUSTION AND SYSTEM FANS ON RESET OR REPLACE ROLLOUT SWITCH BURNER CONTROL LED 4 flashes MAIN VALVE OFF COMBUSTION SYSTEM FANS ON SEQUENCE HOLDS UNTIL SWITCH CLOSES BURNER CONT...

Page 24: ...NO NO YES YES DOES UNIT OPERATE CHECK 1 UNIT POWER 2 INTERLOCK SWITCH 3 TRANSFORMER 4 LIMIT SWITCH END OF TEST REPLACE THE VSP2 1 HEATING MODE NO YES YES YES AFTER THE SELECTED TIME DOES BLOWER TURN...

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