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31-5000731   Rev. 0

Maintenance

At the beginning of each heating season, system should 

be checked as follows by a qualified service technician:

If a high-efficiency filter is being installed as part of this 

system to ensure better indoor air quality, the filter must 

be properly sized. High-efficiency filters have a higher 

static pressure drop than standard-efficiency glass/foam 

filters. If the pressure drop is too great, system capacity 

and performance may be reduced. The pressure drop 

may also cause the limit to trip more frequently during 

the winter and the indoor coil to freeze in the summer, 

resulting in an increase in the number of service calls.
Before  using  any  filter  with  this  system,  check  the 

specifications provided by the filter manufacturer against 

the data given in the appropriate Product Specifications. 

 IMPORTANT

Fire  Hazard.  Use  of  aluminum  wire  with  this  product 

may result in a fire, causing property damage, severe 

injury or death. Use copper wire only with this product.

 WARNING

Failure to use properly sized wiring and circuit breaker 

may result in property damage. Size wiring and circuit 

breaker(s) per Technical Specifications and unit rating 

plate.

 WARNING

1. 

Check wiring for loose connections, voltage at indoor 

unit and amperage of indoor motor.

2. 

Check the condition of the belt and shaft bearings if 

applicable.

3. 

Inspect all gas pipe and connections for leaks.

4. 

Check the cleanliness of filters and change if necessary 

(monthly).

Furnace Cabinet 

Width

Filter Size

Side Return

Bottom Return

14-1/2”

16 x 25 x 1 (1)

14 x 25 x 1 (1)

17-1/2”

16 x 25 x 1 (1)

21”

20 x 25 x 1 (1)

Table 12. 

5. 

Check  the  condition  and  cleanliness  of  burners  and 

heat exchanger and clean if necessary.

6. 

Check  the  cleanliness  of  blower  assembly  and 

clean the housing, blower wheel and blower motor if 

necessary.  The  blower  motors  are  prelubricated  for 

extended bearing life. No further lubrication is needed.

7. 

Inspect  the  combustion  air  inducer  and  clean  if 

necessary.

8. 

Evaluate  the  heat  exchanger  integrity  by  inspecting 

the  heat  exchanger  per  the  AHRI  heat  exchanger 

inspection procedure. This procedure can be viewed 

at www.ahrinet.org.

9. 

Ensure  sufficient  combustion  air  is  available  to  the 

furnace. Fresh air grilles and louvers (on the unit and 

in  the  room  where  the  furnace  is  installed)  must  be 

properly  sized,  open  and  unobstructed  to  provide 

combustion air.

10. 

Inspect  the  furnace  venting  system  to  make  sure 

it  is  in  place,  structurally  sound,  and  without  holes, 

corrosion, or blockage. Vent system must be free and 

clear  of  obstructions  and  must  slope  upward  away 

from the furnace. Vent system should be installed per 

the National Fuel Gas Code.

11. 

Inspect  the  furnace  return  air  duct  connection  to 

ensure  the  duct  is  sealed  to  the  furnace.  Check  for 

air leaks on supply and return ducts and seal where 

necessary.

12. 

Check the condition of the furnace cabinet insulation 

and repair if necessary.

13. 

Perform  a  complete  combustion  analysis  during 

the  furnace  inspection  to  ensure  proper  combustion 

and  operation.  Consult  Service  Literature  for  proper 

combustion values.

14. 

Verify operation of CO detectors and replace batteries 

as required.

Perform  a  general  system  test.  Turn  on  the  furnace  to 

check operating functions such as the start-up and shut-off 

operation.

1. 

Check  the  operation  of  the  ignition  system,  inspect 

and clean flame sensor. Check microamps before and 

after.  Check  controls  and  safety  devices  (gas  valve, 

flame  sensor,  temperature  limits).  Consult  Service 

Manual  for  proper  operating  range.  Thermal  Limits 

should  be  checked  by  restricting  airflow  and  not 

disconnecting the indoor blower. 

2. 

Verify  that  system  total  static  pressure  and  airflow 

settings are within specific operating parameters.

3. 

Clock gas meter to ensure that the unit is operating 

at the specified firing rate. Check the supply pressure 

and the manifold pressure. On two-stage gas furnaces 

check the manifold pressure on high fire and low fire. 

If manifold pressure adjustment is necessary, consult 

the  Service  Literature  for  unit  specific  information 

on  adjusting  gas  pressure.  Not  all  gas  valves  are 

adjustable. Verify correct temperature rise.

Summary of Contents for GE NF80UV

Page 1: ...31 5000731 Rev 0 11 22 GEA NF80UV 80 Upflow Horizontal Two Stage Variable Speed Gas Furnace Service Manual READ CAREFULLY KEEP THESE INSTRUCTIONS...

Page 2: ...l injury or death Electric shock hazard Can cause injury or death Before attempting to perform any service or maintenance turn the electrical power to unit OFF at disconnect switch es Unit may have mu...

Page 3: ...SICAL AND ELECTRICAL DATA Model Input Btuh Output Btuh AFUE ICS Nominal Cooling Capacity Gas Inlet in Volts Hz Phase Max Time Delay Breaker or Fuse Nominal F L A Trans V A Approx Shipping Weight lbs U...

Page 4: ...orm 1977 1773 1759 1405 Norm 2015 1710 1560 1400 1779 1596 1583 1265 1810 1555 1395 1260 Low Fire 25 55 1977 1783 1497 1431 1st Stage 1560 1355 1230 1065 Norm 1797 1621 1361 1301 Norm 1425 1205 1085 9...

Page 5: ...iption Natural to LP Kits 11K48 Two Stage 0 7500 ft 11K47 Two Stage 7500 ft Return Air Base 68W61 14 5 Inch A Width 68W62 17 5 Inch B Width 68W63 21 0 Inch C Width Note For vent length and clearances...

Page 6: ...3 8 137 Right 1 9 16 40 Left 33 838 3 1 8 79 1 15 16 49 14 356 9 16 14 3 76 Right 6 3 4 171 Left 2 FLUE OUTLET Either Side 3 OPTIONAL EXTERNAL SIDE RETURN AIR FILTER KIT Either Side 16 406 14 3 4 375...

Page 7: ...Figure 1 Expanded View HEAT EXCHANGER CABINET COMBUSTION AIR INDUCER BLOWER ASSEMBLY BURNER BOX ACCESS PANELS COMBUSTION AIR INDUCER PRESSURE SWITCH GAS VALVE CONTROL BOX Includes two stage integrate...

Page 8: ...ignition and ignitor durability The control provides gas ignition safety checks and indoor blower control with two stage gas heating The furnace combustion air inducer gas valve and indoor blower are...

Page 9: ...100 CFM count the flashes and multiply by 100 to determine the actual CFM delivered for example 5 flashes x 100 500 CFM Pin Function 1 Gas Valve Second Stage 2 Second Stage Prove Switch 3 Rollout Swit...

Page 10: ...Humidifier 120VAC Line Input 120VAC XFMR Transformer 120VAC EAC Indoor Air Accessory 120VAC Cool Cool Speed 120VAC Park 1 Dead terminal for alternate speed tap Park 2 Dead terminal for alternate spee...

Page 11: ...e bearings MOTOR CONTROLLER J49 J48 Figure 5 GenTeq Blower Motor B3 STATOR WINDINGS OUTPUT SHAFT BEARING ROTOR Figure 6 Blower Motor Components Internal Operation Each time the controller switches a s...

Page 12: ...e motor Jack J48 is the power plug Line voltage must be applied to J48 pins 4 and 5 in order for the motor to operate When using 120VAC pins 1 and 2 must be jumpered Jack J49 connects the unit control...

Page 13: ...AT output from controller to motor windings O volts 325VDC One revolution O volts 325VDC O volts 325VDC WINDING 1 WINDING 2 WINDING 3 O volts 325VDC O volts 325VDC O volts 325VDC WINDING 1 WINDING 2 W...

Page 14: ...Heat Call Figure 10 Indoor Blower Operation High Heat W2 Call Figure 11 Indoor Blower Operation Call for Fan Percentage of High Stage Cooling Figure 12 Indoor Blower Operation Single Stage Cooling Fi...

Page 15: ...ee Figure 14 The limit is a N C SPST manual reset limit When S47 senses rollout the circuit breaks and the ignition control immediately stops ignition and closes the gas valve Rollout can be caused by...

Page 16: ...Page 16 31 5000731 Rev 0 Gaskets Collector Box Orifice Plate Flue Transition Pressure Switch Combustion Air Inducer Manifold And Gas Valve Ignitor Sensor Rollout Switches Figure 14 Heating Components...

Page 17: ...nd Connect Alligator Clip to Flame Sensor Lead Flame Sensor Terminal Remove Sensor Wire from Integrated Control and Connect Alligator Clip to Terminal on Control DIGITAL METER To Control Sensor Termin...

Page 18: ...r probes in order not to damage plug Check voltage during 20 second ignitor warm up period Voltage should read 120 volts 10 If voltage reads below these values check for correct supply voltage to furn...

Page 19: ...combustion air inducer is operating It closes a circuit to the integrated control when pressure inside the combustion air inducer decreases to a certain set point Set points vary depending on unit siz...

Page 20: ...nducer then reinstall the mounting screws See unit Installation Instructions for more detail The combustion air pressure switch must be moved for horizontal discharge air left position IMPORTANT vent...

Page 21: ...nd to move the switch Never use tools If the switch will not turn or if the control switch will not move by hand do not try to repair it Placing the Furnace into Operation These units are equipped wit...

Page 22: ...lock out If the unit locks out again call the service technician to inspect the unit for blockages 10 Is pressure switch closed Obstructed flue will cause unit to shut off at pressure switch Check fl...

Page 23: ...Table 9 for manifold pressures and Table 10 for pressure switch and gas conversion kits Capacity Gas Orifice Size 0 7500 ft 1 Orifice Size 7501 10000 ft Manifold Pressure in w g 0 4500 ft Manifold Pr...

Page 24: ...load indicates a poor or partial ground Compare the readings to Table 11 If the readings exceed the maximum shown in Table 11 make repairs before operating the furnace 2 In addition measure the AC vol...

Page 25: ...F listed on the unit rating plate Supply Air Return Air Supply Duct Temperature Return Duct Temperature _ Temperature Rise Figure 23 Temperature Rise External Static Pressure 1 Tap locations shown in...

Page 26: ...ssary 8 Evaluate the heat exchanger integrity by inspecting the heat exchanger per the AHRI heat exchanger inspection procedure This procedure can be viewed at www ahrinet org 9 Ensure sufficient comb...

Page 27: ...acuum cleaner with a soft brush attachment over the face of burners Visually inspect inside the burners and crossovers for any blockage caused by foreign matter Remove any blockage Figure 26 shows bur...

Page 28: ...Collector Box Orifice Plate Flue Transition Pressure Switch Combustion Air Inducer Manifold And Gas Valve Retention Rings Cross Over Ignitor Flame Sensor Rollout Switches Figure 26 Burner Combustion A...

Page 29: ...TRAL TAP TO NEUTRAL TERMINAL ON IGNITION CONTROL 5 DO NOT CONNECT C COMMON CONNECTION BETWEEN INDOOR UNIT AND THERMOSTAT EXCEPT WHEN REQUIRED BY THE INDOOR THERMOSTAT REFER TO THE THERMOSTAT INSTALLAT...

Page 30: ...Page 30 31 5000731 Rev 0 Figure 28 Wiring Schematic...

Page 31: ...ains energized until the limits are closed Fan On When the thermostat is set for continuous fan operation and there is no demand for heating or cooling a call for fan closes the R to G circuit and the...

Page 32: ...Printed in the U S A All specifications and illustrations subject to change without notice and without incurring obligations...

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