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4.

Disconnect wires from rollout switch.

5.

Remove manifold or burner/manifold assembly.

Manifold  ONLY
a.

Remove the No. 10 screws that secure the
manifold pipe to both legs of the manifold
assembly. 

The manifold pipe must be

supported during this step, or it could fall and
damage the furnace or cause bodily injury!

b.

Slide the manifold pipe (with valve and orifice)
forward, out of the furnace.

Burner/Manifold  Assembly
a.

Remove the No. 10 screws that secure the
burner/manifold assembly legs to the furnace. 

The manifold pipe must be supported during
this step, or it could fall and damage the
furnace or cause bodily injury!

b.

Slide the burner/manifold assembly forward, out
of the furnace until the assembly is clear of the
manifold retention pins.

c.

Rotate the assembly slightly, in order for the legs
to clear the sides of the cabinet, and remove
through the front of the furnace.

8.

To reinstall the manifold pipe or burner/manifold
assembly, reverse the above steps.

Blower  Removal/Replacement:

Removal
1.

Turn OFF all electrical power to the furnace.

2.

Remove the control box access panel and blower
access panel.

3.

Unplug wires from the blower assembly to the control
box.

4.

Remove the four (4) screws securing the control box
in the unit (two (2) in the cabinet at the sides of the
blower door opening and two (2) at the top rear of the
control box).  Be  sure  to  support  the  control  box  so
that  it  does  not  fall!

5.

Rotate the control box out of the cabinet and support
it so that no strain is placed on any wiring. It may be
necessary to disconnect the electrical supply and
thermostat wiring from the control board.

6.

Remove the blower retaining screws from the front of
each blower leg (See Figure 18). These are the two
(2) screws located in the blower compartment that
secure the blower legs to the blower partition panel.

7.

Slide the blower forward about two (2) inches. This
will disengage the rear of the blower legs from the
blower partition. Rotate the front of the blower down
to clear the control box mounting tabs on the
underside of the blower partition, and continue sliding
the blower forward until it is out of the unit. Take
care to clear the control box mounting tabs. If
necessary, disconnect the auxiliary limit leads on the
sides of the blower housing.

Replacement
1.

Place the blower in the blower opening of the unit
and reconnect the auxiliary limit leads.

2.

Slide the blower back, into the unit, taking care to
clear the control box mounting tabs.

3.

When the blower is about halfway into the cabinet,
rotate the rear of the blower UP so that the rear of
the blower legs engage the side rails in the blower
partition.

4.

Continue sliding the blower into the unit until the front
of the blower housing is behind the control box
mounting tabs. Rotate the front of the blower UP
until the legs lie flat against the bottom of the blower
partition, then slide blower fully into position. The
rear of the blower should be against the stop in the
partition and the rear of the blower legs should be
under the partition.

5.

Reattach the two (2) blower securing screws, the
control box, any disconnected wiring, the blower
access panel, and the control box access panel.

Lubricating  Motors:

Direct drive motor and blower assemblies are factory

lubricated and normally do not require oiling. If oiling is
required lubrication of the blower motor is to be
preformed only by a qualified service agency. If the
blower motor on this furnace is to be replaced it must
only be replaced with one of the motors as listed in the
Furnace Blower Specifications on page 3.

Figure 18

BLOWER REMOVAL AND REPLACEMENT

20541501

 

Issue 0240

 

      Page 24 of 26

Summary of Contents for MPGA 050 B3

Page 1: ...APPLICATION GUIDE GAS FURNACE Fit s All 80 English 02 2004...

Page 2: ......

Page 3: ...and liquids in the vicinity of this or any other appliance Installation and service must be performed by a qualified installer service agency or the gas supplier Installation by an unqualified person...

Page 4: ...or the detection of leaks to check all connections as specified in The Gas Connection section on page 16 of these instructions 6 Always install furnace to operate within the furnace s intended tempera...

Page 5: ......

Page 6: ...s in place or A C evaporator in place When operating the furnace in the heating mode the static pressure and the temperature rise supply air temperature minus return air temperature must be within tho...

Page 7: ...FURNACE WIRING SPECIFICATIONS 20541501 Issue 0240 Page 5 of 26...

Page 8: ...lson Boulevard Arlington VA 22209 or the Canadian installation codes obtainable from Canadian Standards Association 178 Rexdale Boulevard Etobicoke Ontario Canada M9W 1R3 This furnace is designed for...

Page 9: ...e furnace is to be installed in a crawl space consult local codes Use of a concrete pad 1 to 2 thick is recommended If the furnace is to be suspended from the ceiling it will be necessary to use steel...

Page 10: ...on of gas proper venting and maintenance of ambient temperature at safe limits under normal conditions of use The furnace shall be located so as not to interfere with proper circulation of air In addi...

Page 11: ...000 60 000 80 000 100 000 120 000 140 000 160 000 100 100 100 100 120 140 160 12 12 12 12 13 14 15 EXAMPLE 50 000 Btuh Furnace 10 000 Btuh Water Heater 60 000 Btuh Total Input 12 Dia Round Duct If ve...

Page 12: ...n of rectangular air ducts must not be less than 3 inches Each opening must have a free area of not less than one square inch per 2 000 Btu per hour of total input of all appliances within the Confine...

Page 13: ...re should be at least one 90 air turn between blower and return grille Further reduction in sound can be accomplished by installing acoustical air turning vanes and or lining the inside of the duct wi...

Page 14: ...ace Under no circumstances should the air flow be such that cooled conditioned air can pass over the furnace heat exchanger This will cause condensation in the heat exchanger and possible failure of t...

Page 15: ...use of one of the following auxiliary draft inducer kits Table 4 AUXILIARY DRAFT INDUCERS Vent Kit MFR Model Furnace Input Field Controls Co SWG 4G 50000 75000 100000 or 125000 Tjernlund Products Inc...

Page 16: ...ssure switch tubing from the combustion blower 3 Remove the four 4 screws that secure the combustion blower adaptor plate to the flue collector box taking care to support the blower assembly so that i...

Page 17: ...ny other gas fired burning appliance to their previous conditions of use ELECTRICAL CONNECTIONS When installed the furnace must be electrically grounded in accordance with local codes or in the absenc...

Page 18: ...ifically for the detection of leaks to check all connections A fire or explosion may result causing property damage personal injury or loss of life The furnace and its individual shutoff valve must be...

Page 19: ...20541501 Issue 0240 Page 17 of 26 THEORY OF OPERATION...

Page 20: ...g completed and the furnace has been properly vented the unit should be started and adjusted for proper operation Check off the following steps as they are completed 1 Be sure all electrical power is...

Page 21: ...of gas flow by using the formula provided below or Table 5 Cubic Ft Hr Number of Dial Revolutions x Cubic Foot Revolution x 3600 Time in seconds Required for Number of Timed Revolutions TABLE 5 Gas R...

Page 22: ...ifold pressure The appropriate manifold pressures based on the elevation and the heating value can be found in Table 7 TABLE 7 High Altitude Manifold Pressure Derate with standard 42 orifice Natural 5...

Page 23: ...h The furnace should be allowed to cool off before attempting to reset the switch Failure to follow these instructions could result in injury due to burns The switch located behind the burner access p...

Page 24: ...SEQUENCE OF OPERATION Direct ignition system control 20541501 Issue 0240 Page 22 of 26...

Page 25: ...This will expose both the burner and flue openings of the primary heat exchangers 6 Vacuum the length of each heat exchanger tube using a straight attachment into the burner openings and the flue ope...

Page 26: ...2 screws located in the blower compartment that secure the blower legs to the blower partition panel 7 Slide the blower forward about two 2 inches This will disengage the rear of the blower legs from...

Page 27: ...TROUBLE SHOOTING With LED Indicator Assistance 20541501 Issue 0240 Page 25 of 26...

Page 28: ...WIRING DIAGRAM 20541501 Issue 0240 Page 26 of 26...

Page 29: ...he CSA International symbols on each nameplate is your assurance that your furnace design meets nationally recognized standards for safety and performance Do not store or use gasoline or other flammab...

Page 30: ...dor of gas is present Use only your hand to adjust the gas control switch never use tools If the switch will not move by hand don t try to repair it call a qualified service technician Force or attemp...

Page 31: ...tat dial or lever to select the temperature you would like the system to maintain Fan Operation You may wish to increase your comfort by setting your system for continuous air circulation of the indoo...

Page 32: ...flashlight will be useful for these inspections Make one inspection prior to the beginning of the heating season and another during the middle Should you observe unusual amounts of any of the followi...

Page 33: ...and place back in furnace To clean a permanent filter shake filter to remove excess dirt and or use a vacuum cleaner Wash filter in soap or detergent water and replace after filter is dry Permanent fi...

Page 34: ...ner Blower Motor Blower Door Shield Top Bottom Blower Wheel Orifice Capacitor Ignitor Blower Support Leg Gas Control Sensor ELECTRICAL GROUP HEAT EXCHANGER GROUP INDUCER GROUP Access Door Primary Heat...

Page 35: ...FURNACE MARKINGS IN FRENCH CONSULT WITH YOUR DEALER OR LOCAL DISTRIBUTOR HAVE AVAILABLE THE MODEL NO AND SERIAL NO LOCATED ON THE UNIT RATING PLATE TO INSURE THE CORRECT FRENCH INSTRUCTION PACKET POUR...

Page 36: ......

Page 37: ...510 88 111 Fax 420 2 579 10 393 e mail janka janka cz LENNOX DISTRIBUTION MOSCOW Tel 7 095 933 29 55 Fax 7 095 926 56 50 e mail lennox dist moscow co ru LENNOXSLOVENSKOs r o Tel 421 7 44 87 19 27 Fax...

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