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Page 24

NO

NO

NO

YES

YES

G25MV VSM BLOWER AND VSP2–1 BLOWER CONTROL BOARD

TROUBLESHOOTING FLOW CHART

DOES UNIT OPERATE?

CHECK:
1–UNIT POWER
2–INTERLOCK SWITCH
3–TRANSFORMER
4–LIMIT SWITCH

REPLACE VSP2–1.

END OF COOLING TEST

CHECK UNIT WIRING

AND IF CORRECT

REPLACE THE

VSP2–1.

COOLING MODE

NO

YES

YES

YES

IS BLOWER ON HIGH SPEED AND ARE DS1 AND

DS3 LIT? DOES THE “CFM” LED–DS4 LIGHT BLINK

ONCE FOR EVERY 100 CFM SELECTED IN THE

TABLES ON PAGE 2?

IN ADDITION TO R AND

G, JUMPER R AND DS.

IS 24 VOLTS PRESENT AT

TERMINAL “VSP2 #12” ON

BURNER CONTROL BOARD?

IS BLOWER ON LOW SPEED AND IS

“ON/OFF” LED–DS3 LIT? “CFM” LED–

DS4 LIGHT SHOULD BLINK ONCE FOR

EVERY 100 CFM SELECTED IN THE

TABLES ON PAGE 2.

CHECK UNIT WIR-

ING AND IF COR-

RECT, REPLACE

VSP2–1.

PLACE JUMPER ACROSS R AND G.

IS 24VAC ACROSS

R AND C?

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 OFF?

PLACE “HTG. BLOWER”

JUMPER IN POSITION #1.

R AND W1 REMAIN JUMPERED.

1–CHECK UNIT WIRING AND IF

CORRECT, REPLACE VSP2–1.

PLACE “HTG. BLOWER” JUMPER IN POSITION #2.

PLACE JUMPER ACROSS R AND W1. WAIT 75

SECOND FOR PREPURGE AND FAN“ON” DELAY.

IS 24VAC ACROSS

R AND C?

2–BREAK AND REMAKE JUMPER

(R TO W1).

3–AFTER 30–35 SECOND

PURGE, IS 24VAC PRESENT
AT GAS VALVE?

REPLACE VSP2–1.

REMOVE JUMPERS

YES

NO

CHECK UNIT WIRING

AND IF CORRECT,

REPLACE VSP2–1.

NO

IS BLOWER ON LOW SPEED AND IS “ON/OFF” LED–

DS3 LIT? “CFM” LED–DS4 LIGHT SHOULD BLINK

ONCE FOR EVERY 100 CFM SELECTED IN THE

TABLES ON PAGE 2.

DOES BLOWER SHIFT TO HEAT SPEED

AND IS “HEAT” LED–DS2 ON? DOES

THE “CFM” LED–DS4 LIGHT BLINK

ONCE FOR EVERY 100 CFM SELECTED

IN THE TABLES ON PAGE 2?

NO

IS 24 VOLTS PRESENT AT

TERMINAL “VSP2 #12” ON

BURNER CONTROL BOARD?

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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