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SERVICE AND TECHNICAL SUPPORT MANUAL

Gas Furnace: N9MSB

Specifications  subject to change without notice.

18

440 04 4412 01

5. Insert the orifices in the support rings of the burners.

NOTE

:  If manifold does not fit flush against the burner, do not

force the manifold on the burner assembly. The burners are not
fully seated forward in the burner assembly. Remove the

manifold and check burner positioning in the burner assembly
assembly before re-installing the manifold.

6. Attach the green/yellow wire and ground terminal to one

of the manifold mounting screws.

7. Install the remaining manifold mounting screws.
8. Check the igniter alignment. See 

Figure 9

Figure 10

and 

Figure 11

.

Figure 10

Igniter Position 

 Top View

A11405

2-1/2-in.

(64.4)

1-1/4-in.

(31.8)

Figure 11

Igniter Position 

 Side View

A12392

2

in.

(2.5 mm

3/8

in.

3/16

in.

, +0.8 -1.5)

(50 mm)

(9.6 mm)

(4.6 mm)

3/32

in., +1/32 -3/64-in.

9. Attach the wires to the roll-out switches.

10. Align the burner  assembly with the openings in the

primary cell inlet panel and attach the burner assembly to

the cell panel.

11. Connect the wire for the flame sensor.

12. Connect the wire for the Hot Surface Igniter.

NOTE

:  Use propane-resistant pipe dope to prevent leaks. Do

not use Teflon tape.

13. Install the gas pipe to the gas valve.

!

WARNING

FIRE OR EXPLOSION HAZARD

Failure to follow this warning could result in personal injury,

death, and/or property damage.
Never purge a gas line into a combustion chamber. Never

test for gas leaks with an open flame. Use a commercially

available soap solution made specifically for the detection of

leaks to check all connections.  A fire or explosion may result

causing property damage, personal injury or loss of life.

14. Check for gas leaks with a commercially available soap

solution made specifically for the detection of leaks.

15. Turn gas on at electric switch on gas valve and at

external shut-off or meter

16. Turn power on at external disconnect, fuse or circuit

breaker.

17. Run the furnace through two complete heating cycles to

check for proper operation

18. Install control door when complete.

Servicing Hot Surface Igniter

The igniter does 

NOT 

require annual inspection. Check igniter

resistance before removal.  Refer to 

Figure 9

Figure 10

 and

Figure 11

.

1. Turn off gas and electrical supplies to furnace.
2. Remove control door.
3. Disconnect igniter wire connection.
4. Check igniter resistance. Igniter resistance is affected by

temperature. Only check resistance when the igniter is at

room temperature.
a. Using an ohm meter, check resistance across both

igniter leads in connector.

b. Cold reading should be between 40 ohms and 70

ohms.

5. Remove igniter assembly.

a. Using a 1/4

in. driver, remove the two screws

securing the igniter mounting bracket to the burner

assembly (See 

Figure 9

)

b. Carefully withdraw the igniter and bracket assembly

through the front of the burner  assembly without

striking the igniter on surrounding parts.

c. Inspect igniter for signs of damage or failure.

d. If replacement is required, remove the screw that

secures the igniter on igniter bracket and remove the

igniter.

6. To replace igniter and bracket assembly, reverse items

5a through 5d.

7. Reconnect igniter harness to the igniter, dressing the

igniter wires to ensure there is no tension on the igniter

itself. (See 

Figure 9

)

8. Turn on gas and electrical supplies to furnace.
9. Verify igniter operation by initiating control board self

test

feature or by cycling thermostat.

10. Replace control door.

Flushing Collector Box and Drainage System

ELECTRICAL SHOCK AND FIRE HAZARD

Failure to follow this warning could result in personal

injury, death, and/or property damage.
Turn off the gas and electrical supplies to the furnace

and install lockout tag before performing any

maintenance or service. Follow the operating

instructions on the label attached to the furnace.

!

WARNING

1. Turn off gas and electrical supplies to furnace.
2. Remove control door.
3. Disconnect pressure switch tube from pressure switch

port.

NOTE

:  Ensure the pressure switch tube disconnected from the

pressure switch is higher than the collector box opening or
water will flow out of tube.

Summary of Contents for N9MSB0401410B

Page 1: ...and or pictures or product labels The signal word WARNING is used throughout this manual in the following manner Safety alert symbol When you see this symbol on the unit and in instructions or manual...

Page 2: ...eath WARNING signifies hazards which could result in personal injury or death CAUTION is used to identify unsafe practices which may result in minor personal injury or product and property damage NOTE...

Page 3: ...am of Furnace Drip Leg Gas Valve turned ON Type of Gas Natural Propane Filter Type and Size Check in box the Blower OFF Delay Jumper Heating Position for Fan Time OFF Setting 1 and 2 2 and 3 3 and 4 5...

Page 4: ...structure through drain tube Vent gases contain carbon monoxide which is tasteless and odorless WARNING 1 Remove upper and middle collector box drain plugs opposite of the condensate trap See Figure...

Page 5: ...e at installed altitude from local gas supplier 2 Obtain average yearly gas specific gravity from local gas supplier 3 Find installation altitude range for your installation in the manifold pressure t...

Page 6: ...manifold pressure is outside this range change main burner orifices h When correct input is obtained replace cap that conceal gas valve regulator adjustment screw Main burner flame should be clear blu...

Page 7: ...24 VAC CONNECTIONS P2 HOT SURFACE IGNITOR HSI INDUCER MOTOR IND CONNECTOR 115 VAC L1 LINE VOLTAGE CONNECTION SPARE1 COM BLUE 115 VAC L2 NEUTRAL CONNECTIONS 24 V THERMOSTAT TERMINALS HUMIDIFIER TERMINA...

Page 8: ...300 21 171 343 857 62 58 116 290 22 164 327 818 64 56 112 281 23 157 313 783 66 54 109 273 24 150 300 750 68 53 106 265 25 144 288 720 70 51 103 257 26 138 277 692 72 50 100 250 27 133 267 667 74 48 9...

Page 9: ...42 3 4 42 3 5 42 3 6 3001 800 43 3 8 42 3 2 42 3 3 42 3 4 915 825 43 3 6 43 3 7 43 3 8 42 3 2 850 44 3 8 43 3 5 43 3 6 43 3 7 875 44 3 6 44 3 7 43 3 4 43 3 5 4000 900 44 3 4 44 3 5 44 3 7 44 3 8 1219...

Page 10: ...ding Leaving blower door off will result in incorrect temperature measurements due to possible changes in duct static pressure and airflow FURNACE DAMAGE HAZARD Failure to follow this caution may resu...

Page 11: ...e wires normally connected to thermostat sub base terminals R and W The thermostat anticipator should NOT be in the circuit while measuring current 1 Remove thermostat from sub base or from wall 2 Con...

Page 12: ...685 1630 1570 1495 1415 1330 1230 Yellow 1445 1430 1410 1385 1350 1305 1255 1195 1120 1045 Orange 1250 1240 1225 1200 1170 1130 1090 1040 975 910 Blue 1090 1080 1060 1035 1010 970 930 885 835 765 Red...

Page 13: ...and minimum break point of the switch is 0 05 inches of water column from the nominal break point of the switch The maximum make point of the switch is 0 10 inches of water above the maximum break poi...

Page 14: ...LED 6 A component test sequence will follow 7 Reinstall the Main Control door Component Self Test NOTE The furnace control component test allows all components to run for a short time except the gas v...

Page 15: ...rvice as necessary 4 Inspect burner compartment before each heating season for rust corrosion soot or excessive dust If necessary have furnace and burner serviced by a qualified service agency 5 Inspe...

Page 16: ...t on blower wheel remove wheel from the blower housing and wash it with an appropriate degreaser To remove wheel a Mark blower wheel location on shaft before disassembly to ensure proper reassembly b...

Page 17: ...old or damaging the mounting to the burner assembly ELECTRICAL SHOCK AND FIRE HAZARD Failure to follow this warning could result in personal injury death and or property damage Turn off the gas and el...

Page 18: ...furnace through two complete heating cycles to check for proper operation 18 Install control door when complete Servicing Hot Surface Igniter The igniter does NOT require annual inspection Check ignit...

Page 19: ...e tubing to prevent any sags or traps in the tubing 6 Connect condensate drain elbow or drain extension elbow to the condensate trap 7 Connect the leads of the condensate heat pad if used 8 Connect ex...

Page 20: ...ratures may be 32_ F 0_ C or lower freeze protection measures must be taken to prevent property or product damage CAUTION Since the furnace uses a condensing heat exchanger some water will accumulate...

Page 21: ...SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace N9MSB Specifications subject to change without notice 440 04 4412 01 21 Figure 14 Service Label 338310 2 Rev F...

Page 22: ...SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace N9MSB Specifications subject to change without notice 22 440 04 4412 01 Figure 15 Wiring Diagram 339241 2 Rev A...

Page 23: ...quence Gas valve and humidifier will not be turned on Inducer motor will start and remain on until the end of the blower test then off The following components are on for 10 15 seconds each individual...

Page 24: ...onent test Does the igniter glow orange white by the end of the 15 second warm up period Unplug igniter harness from control and repeat component test Check for 115V between connector P2 HSI and NEUTR...

Page 25: ...ds after the gas valve GV is energized Simultaneously the electronic air cleaner terminal EAC is energized and remains energized as long as the blower motor BLWM is energized f Heat Off Delay When the...

Page 26: ...dule when used Inducer motor capacitor when used Collector box Condensate trap Condensate trap elbow Gaskets WARNING FIRE EXPLOSION ELECTRICAL SHOCK AND CARBON MONOXIDE POISONING HAZARD Failure to fol...

Page 27: ...T Two stage FEATURE B Base AFUE Efficiency E Extra AFUE Efficiency C Communicating D Dual Certified 2 pipe or 1 pipe R 2 pipe only S Single stage T Two stage N Standard L Low Nox FEATURE 040 40 000 BT...

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