Lennox G24M SERIES Скачать руководство пользователя страница 14

Page 14

C--Combustion Air Blower (B6)

All G24M units use a combustion air blower to move

air through the burners and heat exchanger during

heating operation. Some early model G24M units are

equipped with a blower that uses a PSC (Permanent

Split Capacitor) 120VAC motor. PSC motors use run

capacitors. Other early and late model G24M units are

equipped with a blower that uses a shaded pole 120V

motor. The motor operates during all heating opera-

tion and is controlled by furnace control A3. For G24M

units equipped with the Ram ignition system, the

blower will operate for 45 seconds before burner igni-

tion (pre-purge) and for 5 seconds after the gas valve

closes (post-purge). For G24M units equipped with the

SureLight ignition system, the blower will operate for

15 seconds before burner ignition (pre purge) and for 5

seconds after the the gas valve closes (post purge).
A pressure switch connected to the combustion air

blower housing is used to prove combustion air blower

operation. The switch monitors air pressure in the blow-

er housing. During normal operation, the pressure in the

housing is negative. If pressure becomes less negative

(signifying an obstruction) the pressure switch opens.

When the pressure switch opens, the furnace control

(A3) immediately closes the gas valve to prevent burner

operation.

D--Flame Rollout Switches (S47)

Flame rollout switch is a high temperature limit lo-

cated on top of the burner box. Each furnace is

equipped with two identical switches. One switch is

located over the leftmost burner and the other switch

is located over the rightmost burner. The limit is a

N.C. SPST manual-reset limit connected in series

with the ignition control A3. When S47 senses rollout,

the ignition control immediately stops ignition and

closes the gas valve. If unit is running and flame roll-

out is detected, the gas valve will close and ignition

control will be disabled. Rollout can be caused by a

blocked flue or lack of combustion air. The switch is

factory set and cannot be adjusted. The setpoint will

be printed on the side of the limit. The switch can be

manually reset. To manually reset a tripped switch,

push the reset button located on the control.

FIGURE 12

ROLLOUT SWITCH (S47)

MANUAL

RESET BUTTON

E--Primary Limit Control (S10)

FIGURE 13

G24M SERIES UNITS

LIMIT CONTROL FOR

THIS TYPE AUTO-RESET LIMIT

IS USED FOR THE PRIMARY LIMIT (S10) AND

RIGHT SECONDARY LIMIT (S21)

(see FIGURE 11)

The primary limit (S10) on G24M units is located in the

middle of the heating vestibule panel. When excess heat

is sensed in the heat exchanger, the limit will open. If the

limit is tripped, the furnace control energizes the supply

air blower and closes the gas valve. The limit automati-

cally resets when unit temperature returns to normal.

The switch is factory set and cannot be adjusted. The

switch may have different setpoints for each unit model

number. However, the setpoint will be printed on the

side of the limit.

F--Secondary Limit Controls (S21)

The secondary limit (S21) on G24M units is located in the

blower compartment in the back side of the blower

housing. When excess heat is sensed in the blower

compartment, the limit will open. If the limit is tripped,

the furnace control energizes the supply air blower and

closes the gas valve. The limit automatically resets when

unit temperature returns to normal. The switch is factory

set and cannot be adjusted. Two limits are supplied in

each furnace and each limit is a different style (figures

13 and 14). The setpoint will be printed on the side of

the limit. If stick limit (figure 14) suffers from nuisance

trips anf the furnace is in the horizontal position, re-

place with limit kit no. 50L98.

INSULATING COVER (s)

FIGURE 14

SECONDARY LIMIT CONTROL (S21)

FOR G24M SERIES UNITS

SP

ADE

CONNECTORS

INSULA

TING

COVER

LIMIT

LIMIT

THIS TYPE AUTO-RESET LIMIT IS

USED FOR THE LEFT SECONDARY

LIMIT (S21) (see FIGURE 11)

G--Spark Electrode and Flame Sensor

Early Model G24M Units

Figure 15 shows the arrangement of flame sensor,

spark electrode and burners. The ignition control uses

direct spark to ignite the rightmost burner and the

burners cross-light to the left. The flame sensor uses

flame rectification to sense combustion. A flame

retention ring in the end of each burner is used to

maintain correct flame length and shape and to keep

the flame from lifting off the burner head.

Figure 16 shows the gap between tip of the electrodes
and the burner surface.

Содержание G24M SERIES

Страница 1: ...of local or state codes the guidelines and procedures outlined in this manual except where noted are recommended only and do not constitute code SPECIFICATIONS Model No G24M2 X 45 G24M2 60 G24M3 X 60...

Страница 2: ...characteristics 120 volts 60 hertz 1 phase less than 12 amps All models H Optional Accessories Must Be Ordered Extra H LPG propane kit LB 69845L 38K84 LB 69845K 81J14 Twinning Kit 96J69 5 lbs 2 kg Up...

Страница 3: ...6 x 20 x 1 Filter Rack No Size of Filters mm 2 406 x 508 x 25 Down flow Combustible Floor Base LB 79239B 67J92 10 lbs 4 kg LB 79239C 67J93 12 lbs 5 kg Sidewall Power Venting Kit 79J15 25 lbs 11 kg Han...

Страница 4: ...e Also see Filter Air Resistance table G24M4 75 G24M3 4 100 AND G24M3 4 120 BLOWER PERFORMANCE External Static Air Volume at Various Blower Speeds External Static Pressure High Medium High Medium Medi...

Страница 5: ...0 1125 2105 995 1930 910 1675 790 1480 700 30 75 2360 1115 2090 985 1915 905 1670 790 1470 695 40 100 2310 1090 2050 965 1870 880 1650 780 1440 680 50 125 2260 1065 2000 945 1810 855 1610 760 1410 665...

Страница 6: ...RY LIMITS FRONT LOUVERED PANEL DOOR INTERLOCK SWITCH CONTROL BOARD TRANSFORMER PRESSURE SWITCH NOx TURBULATOR LOW PRESSURE SWITCH Propane Only PRIMARY LIMIT FIGURE 2 HEATING COMPONENTS shown in horizo...

Страница 7: ...PRIMARY LIMIT ROLLOUT SWITCHES SURELIGHT IGNITOR FIGURE 4 To Access Blower 1 Turn off power to unit and disconnect L1 and L2 line voltage power 2 Disconnect thermostat wiring connec tions from furnac...

Страница 8: ...Shock hazard Disconnect power before servicing Control is not field repairable If control is inoperable simply replace entire control Can cause injury or death Unsafe operation will result if repair...

Страница 9: ...ration signaled when heating demand initiated at thermostat SLOW FLASH ON Primary or Secondary limit open Units with board 63K8901 or 24L85 Limit must close within 5 trials for ignition or board goes...

Страница 10: ...20 seconds after which the gas valve opens for a 4 second trial for ignition The ignitor stays en ergized for the first second of the 4 second trial G24M units with 63K89 24L85 or 56L83 the ignitor s...

Страница 11: ...e After a demand the combustion air blower continues to operate for 5 seconds post purge before stopping Post purge allows the heat exchanger to be cleared of combustion products Ignition Control The...

Страница 12: ...he indoor blower starts after a 45 second delay Gas valve remains open and blower continues to run until demand stops flame sensor senses loss of flame a limit opens or the prove switch opens If any o...

Страница 13: ...C Out T o Rollout Switches RO IN J20 P20 Pin 15 24VAC In From Rollout Switches SPARK ELECTRODE Male Spark Plug Type High Voltage Out T o Spark Electrode FS J20 P20 Pin 12 Flame Microamp Sensing FIGURE...

Страница 14: ...ly reset a tripped switch push the reset button located on the control FIGURE 12 ROLLOUT SWITCH S47 MANUAL RESET BUTTON E Primary Limit Control S10 FIGURE 13 G24M SERIES UNITS LIMIT CONTROL FOR THIS T...

Страница 15: ...ition control 24V applied to the terminals energizes the valve Inlet and outlet pressure taps are located on the valve A regulator adjustment screw is located on the valve Refer to figure 17 or 18 for...

Страница 16: ...y and Seasonal Checks 1 Inspect electrical wiring both field and factory installed for loose connections Tighten as required 2 Check voltage at disconnect switch Voltage must be within range listed on...

Страница 17: ...ent dam age to gas valve or overfire For natural gas units op erating pressure at unit gas connection must be be tween 5 0 W C and 13 0 W C For L P gas units operating pressure at unit gas connection...

Страница 18: ...itudes Refer to table 12 for pressure switch replacement for models at elevations of 4500 feet 1372m and greater TABLE 11 ALTITUDE feet m GAS FUEL MANIFOLD PRESSURE in W C kPa 0 4500 Natural 3 5 0 87...

Страница 19: ...unit rating plate To Measure Temperature Rise 1 Place plenum thermometers in the supply and return air plenums Locate supply air thermometer in the first horizontal run of the plenum where it will no...

Страница 20: ...SE CURELY IN PLACE E Blower Speed Taps Leaded Motors Blower speed tap changes are made on the SureLight control board See figure 6 Unused taps must be secured on dummy terminals PARK M1 and or PARK M...

Страница 21: ...tial for gas leaks fire or explosion Some soaps used for leak detection are corrosive to certain metals Carefully clean piping thor oughly after leak detection has been completed Can cause damage to p...

Страница 22: ...92 7 7 3 0 5 1 5 0 1 851 6 167 5 75 16 250 5 225 17 5 2 6 7 20 867 21 5 2 5 35 6685 6 7 1 7 5 35 0 5 0 7 0 52 287 6 7 6 85 COMPRESSOR COMMON POWER HEAT INDOOR BLOWER COMMON HS UNIT COMMON HS UNIT COMP...

Страница 23: ...lower nears full speed combustion air prove switch S18 closes 5 When S18 closes assuming the flame rollout switch S47 primary limit S10 and secondary limits S21 are closed the furnace control begins a...

Страница 24: ...N RESET THERMOSTAT LED 5 flash if flame sensed with valve off LED Steady on if control board failure NO NO CHECK TO SEE IF MAIN VALVE IS OFF SEQUENCE HOLDS UNTIL HI LIMIT CLOSES LED 4 flashes NO CHECK...

Страница 25: ...e REMAINS UNCHANGED THROUGHOUT SEQUENCE THERMOSTAT CALLS FOR COOLING SYSTEM FAN SWITCHES TO HEATING SPEED AFTER SELECTED DELAY ACC TERM REMAINS ENERGIZED SYSTEM FAN SWITCHED TO COOLING SPEED ACC TERMI...

Страница 26: ...Pressure Switch delay Once S18 closes a 15 second pre purge follows 4 SureLight control energizes ignitor A 20 second warm up period begins 5 Gas valve opens for a 4 second trial for ignition Ignitor...

Страница 27: ...G SPEED LED 1 SLOW FLASH LED 2 OFF GAS VALVE OFF COMBUSTION AIR BLOWER OFF INDOOR BLOWER OFF WITH DELAY LED 1 OFF LED 2 SLOW FLASH Sequence holds until pressure switch closes or thermostat resets cont...

Страница 28: ...TO SENSE FLAME FOR FIVE CONSECUTIVE TRIES DURING A SINGLE HEAT DEMAND IGNITION WATCHGUARD MODE GAS VALVE OFF COMBUSTION AIR INDUCER OFF INDOOR BLOWER OFF WITH DELAY LED 1 ALT SLOW FLASH LED 2 ALT SLO...

Страница 29: ...CHANGED THROUGHOUT COOLING CYCLE THERMOSTAT CALLS FOR COOLING COMPRESSOR CONTACTOR AND SYSTEM FAN ENERGIZED WITH 0 SECOND DELAY ACB COOL SPEED AND ACC TERM ENERGIZED COMPRESSOR OFF THERMOSTAT OPENS AC...

Страница 30: ...Y THERMOSTAT OPENS COMBUSTION AIR AND HTG ACC TERMINAL DE ENERGIZE SYSTEM FAN SWITCHED TO ACB COOL SPEED ACC TERM REMAINS ON THERMOSTAT OPENS BOARD 63K89 SYSTEM FAN OFF ACC TERM OFF AFTER OFF DELAY CO...

Страница 31: ...ch open ACTION 1 Manually reset the roll out switch by pushing the top button ACTION 2 Determine the cause of the roll out switch activation before leaving furnace out code LED 1 O 1 2 2 Roll out swit...

Страница 32: ...ternating Fast Flash 2 1 2 Broken or failed ignitor ACTION 1 Unplug ignitor and read resis tance across ignitor If resistance does not read between 10 9 and 19 7 ohms replace the ignitor PROBLEM 3 UNI...

Страница 33: ...with a heating demand Diagnostic lights flash the pres sure switch failure code 2 5 min utes after heating demand 4 1 2 Pressure switch does not close due to obstructions in the pressure lines ACTION...

Страница 34: ...atisfying T stat demand Diagnostic lights flash the pres sure switch code LED 1 Off LED 2 Slow Flash 6 1 1 Low pressure differential at the pressure switch ACTION 1 Check for restricted vent inlet or...

Страница 35: ...rsootingdepositsoroth er restrictions in the heat exchanger assem bly Cleanassemblyasoutlinedininstruction manual ACTION 2 ForG24Mgasfurnaces checkfor proper combustion and flow CO2 should measurebetw...

Страница 36: ...ated ACTION 1 Check sense rod for contamina tion or coated surface Clean the sense rod with steel wool or replace sensor DO NOT USE SAND PAPER TO CLEAN ROD SAND PAPER WILL CONTRIBUTE TO THE CON TAMINA...

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