background image

DUCTING

The proper sizing of warm air ducts is necessary to insure satisfactory heating operation. Ductwork should be in

accordance with the latest editions of (U.S.) NFPA-90A (Air  Conditioning  Systems) and NFPA-90B (Warm  Air  Heating
and  Air  Conditioning  Systems) or Canadian equivalent.

Ductwork  Recommendation:

The supply duct work should be attached to the

flanged opening provided at the discharge end of the
furnace. See page 3 "Furnace Specificatons" for the
dimensions of this opening.

A left, right, or bottom return air opening must be

used as determined by the layout of the installation. An
externally mounted air filter is required.

This furnace has a two piece bottom panel. For

bottom or end duct return, remove the back portion of the
bottom panel by removing the four (4) screws - two (2) on
each side toward the back of the furnace (See Figure 7).
Tilt furnace toward the front, the back portion of the panel
will drop down. Then the back portion can be removed
by pulling toward the back of the furnace.

Figure 7

BOTTOM PANEL REMOVAL

Knockouts are provided on both sides of the furnace

to facilitate the cutout required to the return air ductwork.

Furnace cutouts must be the full size specified by the
corner markers. Undersized cutouts will adversely
affect the airflow capability of the furnace and could
cause overheating of the heat exchanger.

The following recommendations should be followed

when installing the ductwork:
1.

Install locking-type dampers in all branches of the
individual ducts to balance out the system. Dampers
should be adjusted to impose the proper static at the
outlet of the furnace.

2.

Noncombustible flexible duct connectors are
recommended to connect both the supply and return
ducts to the furnace.

3.

In cases where the return air grille is located close to
the blower inlet, there 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 with acoustical material.

4.

It is recommended that the supply duct be provided
with a removable access panel. This opening shall
be accessible when the furnace is installed and shall
be of such a size that the heat exchanger can be

viewed for possible openings using light assistance or
a probe can be inserted by sampling the air stream.
The access panel shall be designed so as to prevent
leaks when locked in position. If an air conditioning
coil is installed, the access panel to the coil can be
used for this purpose.

When supply ducts carry air circulated by the
furnace to areas outside the spaces containing the
furnace, the return air shall also be handled by a
duct sealed to the furnace casing and terminating
outside the space containing the furnace. Incorrect
ductwork termination and sealing will create a
hazardous condition that could lead to bodily harm.

Air openings, intake and outlet pipes, return air
grilles and warm air registers must not be
obstructed.

To  Convert  to  Downflow  Position:

1.

Convert the combustion blower to side flue exit, as
outlined on page 14.

2.

Install proper special base per Table 2 for installation
on combustible flooring (follow instructions supplied
with special base).

3.

It is recommended that the return air be connected to
the bottom panel of the furnace when it is installed in
the downflow position.

NOTE:

SPECIAL SUB-BASE NOT REQUIRED WHEN
FURNACE IS MOUNTED ON A METAL CASED
EVAPORATOR COIL.

Table 2

SPECIAL BASE INSTALLATION

MODEL

SPECIAL BASE

NUMBER

CAT. NO.

MPGA050B3
MPGA075B3

20066501

68L77

MPGA075B4
MPGA100B4

20066502

68L78

MPGA100B5
MPGA100B5

20066503

68L79

NOTE:

Installation on combustible flooring only when
installed on one of the above listed special bases
or as identified on the furnace model and rating
label.

20541501

 

Issue 0240

 

      Page 11 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...

Reviews: