Lennox ML193DF045P36B, ML193DF110P60C, ML193DF070P36B, ML193DF090P48C Unit Information

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Corp. 1026-L5
Service Literature
Revised 03-2014
ML193DF SERIES UNITS
17.6 kW). Refer to Engineering Handbook for proper siz ing.
Units are factory equipped for use with natural gas. A kit is available for conversion to LPG operation. All ML193DF units are equipped with a hot surface ignition system. The gas valve is redundant to assure safety shut-off as required by C.S.A.
The heat exchanger, burners and manifold assembly can be removed for inspection and service. The maintenance section gives a detailed description on how this is done.
ML193DF
All specifications are subject to change. Procedures out lined in this manual are presented as a recommendation only and do not supersede or replace local or state codes.
WARNING
Electric shock hazard. Can cause injury or death. Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at discon nect switch(es). Unit may have multiple power supplies.
Table of Contents
Specifications 2.................................
Optional Accessories 3..........................
Blower Performance Data 4......................
I-Unit Components 6............................
II Placement and Installation 18....................
III-Start-Up 36...................................
IV-Heating System Service Checks 37..............
V-Typical Operating Conditions 39.................
VI-Maintenance 40...............................
VII-Wiring and Sequence of Operation 42...........
WARNING
Improper installation, adjustment, alteration, service or maintenance can cause property damage, person al injury or loss of life. Installation and service must be performed by a licensed professional HVAC in staller (or equivalent), service agency or the gas sup plier.
WARNING
Sharp edges. Be careful when servicing unit to avoid sharp edges which may result in personal injury.
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© 2014 Lennox Industries Inc.
Litho U.S.A.
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SPECIFICATIONS
Gas Heating Performance
Model No. ML193DF045P36B ML193DF070P36B ML193DF090P48C ML193DF110P60C
1
AFUE 93% 93% 93% 93%
Input - Btuh 44,000 66,000 88,000 110,000
Output - Btuh 41,000 61,000 82,000 102,000
Temperature rise range - °F 25 - 55 50 - 80 40 - 70 50 - 80
Gas Manifold Pressure (in. w.g.)
3.5 / 10.0 3.5 / 10.0 3.5 / 10.0 3.5 / 10.0
Nat. Gas / LPG/Propane
High static - in. w.g. 0.50 0.50 0.50 0.50
Connections in.
Intake / Exhaust Pipe (PVC) 2 / 2 2 / 2 2 / 2 2 / 2
Gas pipe size IPS 1/2 1/2 1/2 1/2
Condensate Drain Trap (PVC pipe) - i.d. 1/2 1/2 1/2 1/2
with eld supplied (PVC coupling) - o.d. 3/4 3/4 3/4 3/4
Indoor Blower
Wheel nom. dia. x width - in. 10 x 8 10 x 8 10 x 10 11 ½ x 10
Motor output - hp 1/3 1/3 1/2 1
Tons of add-on cooling 2.5 - 3 2.5 - 3 3 - 4 4 - 5
Air Volume Range - cfm 605 - 1615 560 - 1550 920 - 2145 1210 - 2410
Electrical Data
Blower motor full load amps 6.1 6.1 8.2 11.5
Voltage 120 volts - 60 hertz - 1 phase
Maximum overcurrent protection 15 15 15 15
Shipping Data lbs. - 1 package 124 129 147 162
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1
Annual Fuel Utilization Efciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized
furnaces.
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OPTIONAL ACCESSORIES - MUST BE ORDERED EXTRA
“B” Width Models “C” Width Models
CABINET ACCESSORIES
Downow Combustible Flooring Base 11M60 11M61
CONDENSATE DRAIN KITS
Condensate Drain Heat Cable 6 ft. 26K68 26K68
24 ft. 26K69 26K69
50 ft. 26K70 26K70
Heat Cable Tape Fiberglass - 1/2 in. x 66 ft. 36G53 36G53
Aluminum foil - 2 in. x 60 ft. 16P89 16P89
Crawl Space Vent Drain Kit 51W18 51W18
CONTROLS
Twinning Kit 65W80 65W80
DOWNFLOW FILTER KITS
Downow Air Filter and Rack Kit 51W07 51W08
No. and Size of lter - in. (2) 20 x 20 x 1 (2) 20 x 20 x 1
NIGHT SERVICE KITS
Night Service Kit 51W03 51W03
TERMINATION KITS
See Installation Instructions for specic venting information.
Termination Kits ­Direct Vent Applications
Only
Termination Kits - Direct or Non-Direct vent
Roof Termination Flashing Kit - Direct or Non-Direct Vent ­Contains two ashings
1
Cleanable polyurethane frame type lter.
2
Kits contain enough parts for two, non−direct vent installations.
3
Non-direct vent only.
NOTE - Termination Kits 44W92, 44W93, 30G28, 81J20 are certied to ULC S636 standard for use in Canada only.
Concentric US - 2 in. 71M80 69M29
3 in. - - - 60L46
Canada - 2 in. 44W92 44W92
3 in. - - - 44W93
Flush-Mount 2, 2-1/2 or 3 in. 51W11 51W11
Wall - Close
Couple
Wall - Close
Couple WTK
US - 2 in. 22G44 - - -
3 in. 44J40 44J40
Canada - 2 in. 30G28 - - -
3 in. 81J20 81J20
Roof 2 in. 15F75 15F75
Wall Ring Kit 2 in. 15F74
44J41 44J41
3
15F74
High Altitude
Input
Pressure Switch Kit
4501 - 7500 ft. 7501 - 10,000 ft. 0 - 7500 ft. 0 - 7500 ft. 7501- 10,000 ft.
all models 74W90 74W91 69W73 73W81 73W37
GAS HEAT ACCESSORIES
Natural Gas to
LPG/Propane Kit
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LPG/Propane
to Natural Gas Kit
Natural Gas
High Altitude
Orice Kit
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BLOWER DATA
ML193DF045XP36B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
0.00 1615 650 1385 555 1205 465 1045 390
0.10 1605 640 1375 545 1195 455 1035 380
0.20 1500 620 1340 525 1165 445 1015 370
0.30 1450 590 1290 490 1125 420 975 365
0.40 1350 560 1235 480 1090 405 920 345
0.50 1300 545 1170 450 1035 380 875 335
0.60 1195 500 1095 425 990 365 840 320
0.70 1140 485 1020 400 895 345 780 300
0.80 1025 450 920 370 840 330 695 275
0.90 945 435 800 335 700 295 605 250
ML193DF070XP36B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
0.00 1505 660 1310 570 1090 455 940 390
0.10 1480 625 1295 550 1070 435 935 365
0.20 1405 585 1255 515 1055 425 930 350
0.30 1355 580 1225 475 1045 405 900 330
0.40 1305 540 1165 470 1010 385 890 325
0.50 1270 525 1110 425 975 370 835 305
0.60 1175 500 1080 415 925 345 815 290
0.70 1105 460 1000 395 855 320 745 270
0.80 1040 440 925 365 790 300 670 250
0.90 920 400 825 335 680 270 560 225
Air Volume / Watts at Various Blower Speeds
High
cfm Watts cfm Watts cfm Watts cfm Watts
Air Volume / Watts at Various Blower Speeds
High
cfm Watts cfm Watts cfm Watts cfm Watts
Medium-
High
Medium-
High
Medium-
Low
Medium-
Low
Low
Low
ML193DF090XP48C PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
0.00 2075 800 1890 720 1625 645 1375 535
0.10 1995 755 1830 680 1590 615 1350 515
0.20 1910 715 1775 645 1575 580 1340 500
0.30 1825 680 1705 610 1530 550 1325 485
0.40 1730 645 1620 580 1475 525 1285 460
0.50 1630 615 1530 545 1405 500 1240 440
0.60 1530 585 1450 525 1330 470 1175 420
0.70 1430 555 1340 485 1260 450 1095 390
0.80 1300 525 1245 465 1145 415 1015 370
0.90 1185 495 1110 430 1045 385 915 340
ML193DF110XP60C PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
0.00 2410 1390 2190 1080 1860 910 1560 735
0.10 2405 1385 2180 1070 1855 905 1555 730
0.20 2285 1345 2120 1030 1850 865 1540 720
0.30 2220 1315 2015 1005 1770 840 1535 705
0.40 2185 1295 1950 955 1750 815 1530 685
0.50 2045 1240 1830 925 1680 790 1500 660
0.60 1965 1220 1710 890 1575 755 1445 640
0.70 1820 1165 1610 850 1495 720 1370 615
0.80 1625 1155 1510 820 1400 695 1315 595
0.90 1455 1110 1390 790 1350 660 1210 565
Air Volume / Watts at Various Blower Speeds
High
cfm Watts cfm Watts cfm Watts cfm Watts
Air Volume / Watts at Various Blower Speeds
High
cfm Watts cfm Watts cfm Watts cfm Watts
Medium-
High
Medium-
High
Medium-
Low
Medium-
Low
Low
Low
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CONTROL BOX
(Includes integrated control,
transformer and door switch)
BLOWER MOTOR
BLOWER
ACCESS
PANEL
PARTS ARRANGEMENT
BAG ASSEMBLY
(hidden)
BURNER ACCESS
PANEL
COMBUSTION AIR INDUCER
BLOWER DECK
PRIMARY LIMIT
COLD END HEADER BOX
HEAT EXCHANGER
GAS VALVE
BURNER BOX ASSEMBLY
(includes sensor, rollout switches and ignitor)
FIGURE 1
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I-UNIT COMPONENTS
ML193DF unit components are shown in figure 1. The combustion air inducer, gas valve and burners can be ac cessed by removing the burner access panel. The blower and control box can be accessed by removing the blower access door.
A-Control Box Components (Figure 2)
Unit transformer (T1) and integrated ignition control (A92) are located in the control box. In addition, a door interlock switch (S51) is located in the control box.
ML193DF Control Box
INTEGRATED IGNITION
CONTROL
(A92)
DOOR INTERLOCK
SWITCH (S51)
WARNING
Shock hazard. Disconnect power before servicing. Control is not
field repairable. If control is inoperable, simply re place entire control.
Can cause injury or death. Unsafe operation will result if repair is attempted.
The ignition control system consists of an integrated con trol (figure 4) ignitor (figure 10) and sensor (figure 10). The integrated control and ignitor work in combination to en sure furnace ignition and ignitor durability. The integrated control, controls all maor furnace operations. The inte grated control also features two LED lights (DS1 red and DS2 green) for troubleshooting and two accessory termi nals rated at (1) one amp. The integrated control also fea tures a (3) amp fuse for overcurrent protection. Tables 1 and 2 show jack plug terminal designations. See table 3 for troubleshooting diagnostic codes. The 95 volt ignitor is made from a high strength, silicon nitride material that pro vides long life and trouble free maintenance. The inte grated control continuously monitors line voltage and maintains the ignitor power at a consistent level to provide proper lighting and maximum ignitor life.
TRANSFORMER
(T1)
FIGURE 2
1. Transformer (T1)
A transformer located in the control box provides power to the low voltage section of the unit. The transformers on all models are rated at 40VA with a 120V primary and 24V secondary.
2. Door Interlock Switch (S51)
A door interlock switch rated 14A at 120VAC is located on the control box. The switch is wired in series with line volt age. When the blower door is removed the unit will shut down.
3. Integrated Ignition Control 100973 (A92)
TABLE 1
4-Pin Terminal Designation
PIN # FUNCTION
1 Combustion Air Inducer Line
2
3
4
Ignitor Line
Combustion Air Inducer Neutral
Ignitor Neutral
TABLE 2
12-Pin Terminal Designations
PIN # FUNCTION
1 High Limit Output
2 Not Used
3 24V Line
4 Not Used
5 Rollout Switch Out
6 24V Neutral
7 High Limit Input
8 Ground
9 Gas Valve Common
10 Pressure Switch In
11 Rollout Switch In
12 Gas Valve Out
CAUTION
Electrostatic discharge can affect elec tronic components. Take precautions to neutralize electrostatic charge by touching your hand and tools to metal prior to handling the control.
Electronic Ignition (See Figure 5)
On a call for heat the integrated control monitors the com bustion air inducer prove switch. The integrated control will not begin the heating cycle if the prove switch is closed (by­passed). Once the prove switch is determined to be open, the combustion air inducer is energized. When the differen
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tial in the prove switch is great enough, the prove switch closes and a 15-second pre-purge begins. If the prove switch is not proven within 2-1/2 minutes, the integrated control goes into Watchguard-Pressure Switch mode for a 5-minute re-set period. After the 15-second pre-purge period, the ignitor warms up for 20 seconds after which the gas valve opens for a 4-sec ond trial for ignition. The ignitor remains energized for the first 3 seconds during the 4 second trial. If ignition is not proved during the 4-second period, the integrated control will try four more times with an inter purge and warm-up time between trials of 35 seconds. After a total of five trials for ignition (including the initial trial), the integrated control goes into Watchguard-Flame Failure mode. After a 60-minute reset period, the integrated control will begin the ignition sequence again. The integrated control has an added feature of ignitor pow er regulation to maintain consistent lighting and longer igni tor life under all line voltage conditions.
Fan Control
The fan on time of 30 seconds is not adjustable. The fan off delay (amount of time that the blower operates after the heat demand has been satisfied) may be adjusted by changing the jumper position across the five pins on the integrated control. The unit is shipped with a factory fan off setting of 90 seconds. The fan off delay affects comfort and is adjustable to satisfy individual applications. Adjust the fan off delay to achieve a supply air temperature between 90° and 110°F at the moment that the blower is de-ener gized. Longer off delay settings provide lower return air temperatures; shorter settings provide higher return air temperatures. See figure 3.
FAN‐OFF TIME IN SECONDS
NO JUMPER
To adjust fan-off timing, reposition jumper across pins
to achieve desired setting.
FIGURE 3
LED 1
LED 2
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
TERMINAL DESIGNATIONS
HUM LINE XFMR EAC COOL HEAT PARK FLAME NEUTRALS
3 AMP, 32 VAC FUSE
Humidifier (120VAC) Input (120VAC) Transformer (120VAC) Electronic Air Cleaner (120VAC) Blower - Cooling Speed (120VAC) Blower - Heating Speed (120VAC) Dead terminals to park alternate spd taps Flame sensor Neutral terminals (120VAC)
BLOWER OFF
DELAY JUMPER
FIGURE 4
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The integrated control is equipped with two LED lights for troubleshooting. The diagnostic codes are listed below in table 3.
TABLE 3
DIAGNOSTIC CODES
Make sure to Identify LED'S Correctly.
LED #1 (Red) LED #2 (Green) DESCRIPTION
SIMULTANEOUS
SLOW FLASH
SIMULTANEOUS
FAST FLASH
SLOW FLASH ON
OFF SLOW FLASH
ALTERNATING
SLOW FLASH
SLOW FLASH OFF Flame sensed without gas valve energized.
ON SLOW FLASH Rollout switch open. OR: 12‐pin connector improperly attached.
SIMULTANEOUS
SLOW FLASH
SIMULTANEOUS
FAST FLASH
ALTERNATING
SLOW FLASH
Power on - Normal operation. Also signaled during cooling and continuous fan.
Normal operation - signaled when heating demand initiated at thermostat.
Primary or secondary limit switch open. Limit must close within 3 minutes or unit goes into 1 hour Watchguard.
Pressure prove switch open. OR: Blocked inlet/exhaust vent; OR: Pressure switch closed prior to activation of combustion air inducer.
Watchguard 1 hour -- burners failed to ignite or lost flame 5 times during single heating demand.
ON
ON
OFF
ON
OFF
ON
Circuit control failure or control wired incorrectly.
FAST FLASH SLOW FLASH Main power polarity reversed. Switch line and neutral.
SLOW FLASH FAST FLASH Low flame signal. Measures below 1.5 microamps. Replace flame sense rod.
ALTERNATING
FAST FLASH
ALTERNATING
FAST FLASH
Improper main ground. OR: Line voltage below 90 volts.
NOTE - Slow flash rate equals 1 Hz (one flash per second). Fast flash rate equals 3 Hz (three flashes per second). Minimum flame sense current = 0.5 microAmps.
*4 Sec.Trial
for Ign.
**Blower “On”
Delay
End of
Heat Demand
5 SEC
Post
Purge
Blower
Off
Time
ON
OFF
DEMAND
CAI IGNITOR GAS VALVE INDOOR BLOWER
*Ignitor will energize the first 3 seconds of the 4 second trial for ignition
**Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on “OFF TIME” Setting.
15 Sec.
Pre -Purge
20 sec.
Ignitor Warmup
FIGURE 5
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4. Integrated Ignition Control 103085 (A92)
WARNING
Shock hazard. Disconnect power before servicing. Control is not
field repairable. If control is inoperable, simply re place entire control.
Can cause injury or death. Unsafe operation will re sult if repair is attempted.
The hot surface ignition control system consisting of an in tegrated control (figure 6 with control terminal designations in tables 4 and 5), flame sensor and ignitor (figure 10). The integrated control and ignitor work in combination to en sure furnace ignition and ignitor durability. The integrated control, controls all major furnace operations. The inte grated control also features a RED LED for troubleshooting and two accessory terminals rated at (1) one amp. See table 6 for troubleshooting diagnostic codes. The 120 volt ignitor is made from a high strength, silicon nitride material that provides long life and trouble free maintenance.
Electronic Ignition (Figure 7)
On a call for heat the integrated control monitors the com bustion air inducer pressure switch. The control will not be gin the heating cycle if the pressure switch is closed (by­passed). Once the pressure switch is determined to be open, the combustion air inducer is energized. When the differential in the pressure switch is great enough, the pres sure switch closes and a 15-second pre-purge begins. If the pressure switch is not proven within 2-1/2 minutes, the integrated control goes into Watchguard-Pressure Switch mode for a 5-minute re-set period. After the 15-second pre-purge period, the ignitor warms up for 20 seconds after which the gas valve opens for a 4-sec ond trial for ignition. The ignitor remains energized for the first 3 seconds of the trial for ignition. If ignition is not proved during the trial for ignition, the integrated control will try four more times with an inter purge and warm-up time between trials of 30 seconds. After a total of five trials for ignition (in cluding the initial trial), the integrated control goes into Watchguard-Flame Failure mode. After a 60-minute reset period, the integrated control will begin the ignition se quence again.
TABLE 4
4-Pin Terminal Designation
PIN # FUNCTION
1 Combustion Air Inducer Line
2
3
4
Ignitor Line
Combustion Air Inducer Neutral
Ignitor Neutral
TABLE 5
12-Pin Terminal Designations
PIN # FUNCTION
1 High Limit Output
2 Sensor
3 24V Line
4 Not Used
5 Rollout Switch Out
6 24V Neutral
7 High Limit Input
8 Ground
9 Gas Valve Common
10 Pressure Switch In
11 Rollout Switch In
12 Gas Valve Out
TABLE 6
DIAGNOSTIC CODES
LED Status DESCRIPTION
LED Off
LED On Normal operation.
1 Flash
2 Flashes
3 Flashes
4 Flashes Primary limit switch open.
5 Flashes Rollout switch open.
6 Flashes Pressure switch cycle lockout.
7 Flashes Lockout, burners fail to light.
8 Flashes
9 Flashes Line voltage polarity incorrect.
Note - This control is equipped with a push button switch for diagnostic code recall. The control stores the last 5 fault codes in non-volatile memory. The most recent fault code is flashed first, the oldest fault code is flashed last. There is a 2 second pause between codes. When the push button switch is pressed for less than 5 seconds, the control will flash the stored fault codes when the switch is released. The fault code history may be cleared by pressing the push button switch for more than 5 seconds.
No power to control or control harware fault detected.
Flame present with gas vavle de-energized.
Pressure switch closed with combustion air inducer de-energized.
Pressure switch open with combus tion air inducer energized.
Lockout, buners lost flame too many times.
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LED
ЙЙЙЙЙЙЙЙЙ
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
TERMINAL DESIGNATIONS
HUM LINE XFMR EAC COOL HEAT PARK CONT NEUTRALS
TWIN
Humidifier (120VAC) Input (120VAC) Transformer (120VAC) Indoor Air Qality Accessory Air Cleaner (120VAC) Blower - Cooling Speed (120VAC) Blower - Heating Speed (120VAC) Dead terminals to park alternate spd taps Continuous blower Neutral terminals (120VAC)
Twinning Terminal (24VAC)
TWIN
ON
OFF
DEMAND
CAI IGNITOR GAS VALVE INDOOR BLOWER
*Blower on time will be 30 seconds after flame is sensed. Blower off time will depend on “OFF TIME” Setting.
PUSH BUTTON
Pre -Purge Ignitor Warm-up
15
FIGURE 6
ELECTRONIC IGNITION
351
Trial for
Ignition
FIGURE 7
39
Blower “On”*
Delay
5 SEC69
Post
Purge
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Fan Time Control
Heating Fan On Time
The fan on time of 30 seconds is not adjustable.
Heating Fan Off Time
Fan off time (time that the blower operates after the heat demand has been satisfied) can be adjusted by moving the jumper to a different setting. The unit is shipped with a fac tory fan off setting of 120 seconds. For customized comfort, monitor the supply air temperature once the heat demand is satisfied. Note the supply air temperature at the instant the blower is de-energized. Adjust the fan-off delay to achieve a supply air temperature between 90° - 110° at the instant the blower is de-ener gized. (Longer delay times allow for lower air temperature, shorter delay times allow for higher air temperature). See figure 8.
Cooling Fan On Time
The fan on time is 2 seconds and is not adjustable.
Cooling Fan Off Time
The control has a 60 second fan off delay after cooling de mand has been met. This delay is factory set and not ad justable.
Twinning 2 ML193DF Furnaces
Integrated control 103085 is equipped with a provision to ”twin” (interconnect) two(2) adjacent furnaces with a com mon plenum such that they operate as one (1) large unit.
When twinned, the circulating blower speeds are synchro nized between the furnaces. If either furnace has a need to run the blower, both furnaces will run the blower on the same speed. The cooling speed has highest priority, fol lowed by heating speed and fan speed.
Field installation of twinning consists of connecting wires between the ”C” and ”Twin” terminals of the two controls. The 24 VAC secondary of the two systems must be in phase. All thermostat connections are made to one control only. Figure 9 show wiring for two-stage and single stage thermostats.
The twinned furnace without thermostat connections is to have the call for heat supplied by an external 24VAC isola tion relay to prevent its rollout switch from being bypassed by the other twinned furnace. The coil of the isolation relay connects from the thermostat ”W” to 24 VAC common. The contacts of the relay connect ”R” to ”W” on the non-thermo stat twin.
HEAT FAN‐OFF TIME IN SECONDS
NO JUMPER
To adjust fan-off timing, reposition jumper across pins to
60 Second
off Time
60
90
120
180
achieve desired setting.
90 Second
off Time
60
90
120
180
120 Second
60
off Time
90
120
180
FIGURE 8
180 Second
off Time
60
90
120
180
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FIELD WIRING FOR TWINNING THE ML193DF
TWO-STAGE THERMOSTAT
R
Call For Cool
Y
Call For Fan
G
Call For 1st Stage Heat
Call For 2nd
StageHeat
W1
W2
ISOLATION RELAY
TWIN
TWIN
SINGLE STAGE THERMOSTAT
R
TWIN 1
Y
G
Call For Cool
Call For Fan
Call For Heat
R
Y
G
W
W
C
ISOLATION RELAY
R
TWIN 2
Y
G
W
TWIN
TWIN
R
TWIN 1
Y
G
W
C
R
TWIN 2
Y
G
W
C
C
FIGURE 9
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B-Heating Components
Combustion air inducer (B6), primary limit control (S10), SureLight ignitor, burners, flame rollout switch (S47), gas valve (GV1), combustion air prove switch (S18), and clam shell heat exchangers are located in the heating compart ment. The heating compartment can be accessed by re moving the burner access panel.
1. Ignitor (Figure 10)
ML193DF units use a mini-nitride ignitor made from a pro prietary ceramic material. Ignitor longevity is enhanced by controlling the voltage to the ignitor. Units equipped with control 103085 have a 120V ignitor. Units equipped with control 100973 have a 95V ignitor. See figure 11 and table 7 for resistance and voltage checks.
2. Flame Sensor (Figure 10)
A flame sensor is located on the left side of the burner sup port. The sensor is mounted on the bottom burner box plate and the tip protrudes into the flame envelope of the left­most burner. The sensor can be removed for service with out removing any part of the burners. During operation, flame is sensed by current passed through the flame and sensing electrode. The ignition control allows the gas valve to remain open as long as flame signal is sensed.
NOTE - The ML193DF furnace contains electronic components that are polarity sensitive. Make sure that the furnace is wired correctly and is properly grounded.
3. Flame Rollout Switches (Figure 10)
Flame rollout switches S47 are SPST N.C. high tempera ture limits located on the top left and bottom right of the front buner box plate. S47 is wired to the burner ignition control A92. When either of the switches sense flame rollout (indi cating a blockage in the combustion passages), the flame rollout switch trips, and the ignition control immediately closes the gas valve. Switch S47 in all ML193DF units is factory preset to open at 250_F + a temperature rise. All flame rollout switches are manual reset.
12_F (121_C + 6.7_C) on
SENSOR
ML193DF Burner Box Assembly
IGNITOR
BURNERS
ROLLOUT SWITCHES
FRONT BURNER BOX PLATE
GAS VALVE
FIGURE 10
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IGNITOR CHECKS
TABLE 7
Control Ohms
103085
100973
39 to 70 24 to 47
Voltage +
120
95
10%
Multi−Meter
Test 1
(set to ohms)
Test 2
Check ignitor for correct resistance.
Seperate the 2-pin jack-plug near the manifold and check
resistance of ignitor at the plug. See table 7. If the
reading is correct, then the problem is with the wiring
between the jack-plug and the control. If reading is not
correct, the issue is the ignitor.
Integrated Control Detail
Test 1
Check ignitor circuit for correct resistance.
Remove 4-pin plug from control.
Check ohms reading across terminals 2 and 4.
See table 7. If value is correct, this is the only test
needed. If the reading on the meter is not correct, (0 or
infinity) then a second test is needed.
Multi−Meter
(set to ohms)
Test 2
Integrated Control DetailIntegrated Control Detail
Multi−Meter
(set to VAC)
Test 3
Integrated Control Detail
Test 3
Check ignitor for correct voltage
Insert meter probes into terminals 2 and 4 (use small
diameter probes in order not to damage plug).
Check voltage during 20 second ignitor warm up period. See
table 7. If voltage reads below these values, check for
correct supply voltage to furnace.
FIGURE 11
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Page 15
4. Primary Limit Control (Figure 12)
Primary limit (S10) used on ML193DF units is located in the heating vestibule panel. When excess heat is sensed in the heat exchanger, the limit will open. Once the limit opens, the furnace control energizes the supply air blower and de­energizes the gas valve. The limit automatically resets when unit temperature returns to normal. The switch is fac tory set and cannot be adjusted. For limit replacement re move wires from limit terminals and rotate limit switch 90 degrees. Slowly remove from the vestibule panel. Install replacement limit with same care.
Primary Limit Location and Heat Exchanger
burner input. See table 8 for orifice size. The burner is sup ported by the orifice and will easily slide off for service. A flame retention ring in the end of each burner maintains correct flame length and shape and keeps the flame from lifting off the burner head.
TABLE 8
Gas Orifice Size
Unit Fuel Orifice Size
All Natural 0.0625
All L.P./Propane 0.034
Burner Detail Top Vie w
IGNITOR
Install limit face down
FIGURE 12
5. Heat Exchanger (Figure 12)
ML193DF units use an aluminized steel primary and stain less steel secondary heat exchanger assembly. Heat is transferred to the air stream from all surfaces of the heat exchanger. The shape of the heat exchanger ensures maximum efficiency.
The combustion air inducer pulls fresh air through the burn er box. This air is mixed with gas in the burners. The gas / air mixture is then burned at the entrance of each clam shell. Combustion gases are then pulled through the pri mary and secondary heat exchangers and exhausted out the exhaust vent pipe.
6. Burners (Figure 13)
All units use inshot burners. Burners are factory set and do not require adjustment. Burners can be removed as an as sembly for service. Burner maintenance and service is de tailed in the MAINTENANCE section of this manual. Each burner uses an orifice which is precisely matched to the
SENSOR
ORIFICES
FIGURE 13
7. Gas Valve (GV1)
The ML193DF uses an internally redundant to valve to as sure safety shut‐off. If the gas valve must be replaced, the same type valve must be used.
24VAC terminals and gas control switch are located on top of the valve. All terminals on the gas valve are connected to wires from the ignition control. 24V applied to the terminals opens the valve.
Inlet and outlet pressure taps are located on the valve. A manifold adjustment screw is also located on the valve. An LPG changeover kit is available.
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
(under
barbed
fitting)
INLET
PRESSURE
PORT
Gas Valve
MANIFOLD
PRESSURE
OUTLET
PORT
FIGURE 14
Page 15
Page 16
8. Combustion Air Inducer (B6) & Cold End Header Box
Pressure Switch
All ML193DF units use a combustion air inducer to move air through the burners and heat exchanger during heating op eration. The blower uses a shaded pole 120VAC motor. The motor operates during all heating operation and is con trolled by burner ignition control A3. Blower operates con tinuously while there is a call for heat. The burner ignition control will not proceed with the ignition sequence until combustion air inducer operation is sensed by the proving switches.
The CAI is installed on the cold end header box. The cold end header box is a single piece made of hard plastic. The box has an internal channel where the combustion air in ducer creates negative pressure at unit start up. The chan nel contains an orifice used to regulate flow created by the CAI. The box has pressure taps for the CAI pressure switch hoses. The pressure switch measure the pressure across the CAI orifice or difference in the channel and the box. If
replacement is necessary the gaskets used to seal the box to the vestibule panel and the CAI to the box, must also be replaced.
TABLE 9
ML193DF Unit
C.A.I. Orifice Size
-045 0.618
-070 0.891
-090 1.031
-110 1.297
9. Combustion Air Pressure Switch (Figure 15)
ML193DF series units are equipped with a differential pres sure switch located on the cold end header box. The switches monitor across the CAI orifice to insure proper flow through the heat exchanger.
The switch is a SPST N.O. prove switch electrically con nected to the integrated control. The purpose of the switch is to prevent burner operation if the combustion air inducer is not moving enough air for proper combustion.
BRACKET
24VAC
TERMINALS
TAP
TAP
FIGURE 15
On start‐up, the switch senses that the combustion air in ducer is operating. It closes a circuit to the ignition control when the difference in pressure across the CAI orifice ex ceeds a non-adjustable factory setting. If the switch does not successfully sense the required differential, the switch cannot close and the furnace cannot operate. If the flue or air inlet become obstructed during operation, the switch senses a loss of pressure differential and opens the circuit to the ignition control. If the condensate line is blocked, wa ter will back up into the header box and reduce the pressure differential across the switch. The prove switch opens if the differential drops below the set point. See table 10.
Checks of pressure differential can aid in troubleshooting. When measuring the pressure differential, readings should be taken at the pressure switch. See figure 16. Lack of dif ferential usually indicates problems in the intake or exhaust piping, but may indicate problems in the heat exchanger, condensing coil, header boxes, combustion inducer or oth er components.
TABLE 10
Altitude ft
ML193DF
0 - 4500
4501 -
7500
7501 - 10000
Set Point SetPoint Set Point
-045
-070
-090
-110
-0.65 -0.60 -0.55
*Set point is factory set and non-adjustable
Page 16
Page 17
Measuring Pressure Differential
RED TUBING
NEGATIVE
BLACK TUBING
POSITIVE
1 - Remove thermostat demand and allow unit to cycle off.
2 - Install a tee in the negative (-) line (red tubing) and a tee in the
positive (+) line (black tubing) running from the pressure switch to the cold end header box.
3 - Install a manometer with hose from the negative (-) side of
the manometer to the tee installed in the negative (-) line and with hose from the positive (+) side of the manometer to the tee in the positive (+) line.
NOTE - Both sides of the cold end header box are negative. How ever the (+) port reads less negative pressure than the (-) port.
FIGURE 16
C-Blower Compartment
Blower motor (B3) and capacitor (C4), are located in the blower compartment. The blower compartment can be ac cessed by removing the blower access panel.
Blower Motor Housing
4 - Operate unit and observe manometer reading.
Readings will change as heat exchanger warms.
a. Take one reading immediately after start‐up. b. Take a second reading after unit has reached steady state (approximately 5 minutes). This will be the pressure differential.
The pressure differential should be greater than those listed in table 10.
5 - Remove thermostat demand and allow to cycle off.
6 - Remove manometer and tee's. Reinstall combustion air
sensing hoses to the pressure switch.
1.Blower Motor (B3) and Capacitor (C4)
All ML193DF units use single-phase direct-drive blower motors. All motors are 120V permanent split capacitor mo tors to ensure maximum efficiency. See SPECIFI CATIONS table at the front of this manual for more detail. See motor nameplate for capacitor ratings.
MOTOR
To Remove Blower From Unit: Disconnect Power, Remove Control
Box, Remove Bolts and Unplug Motor Wires From Control Board.
Then Slide Out Front of Unit.
FIGURE 17
BOLTS
CAPACITOR
Page 17
Page 18
II-PLACEMENT AND INSTALLATION
Pipe & Fittings Specifications
All pipe, fittings, primer and solvent cement must conform with American National Standard Institute and the Ameri can Society for Testing and Materials (ANSI/ASTM) stan dards. The solvent shall be free flowing and contain no lumps, undissolved particles or any foreign matter that ad versely affects the joint strength or chemical resistance of the cement. The cement shall show no gelation, stratifica tion, or separation that cannot be removed by stirring. Re fer to the table 11 below for approved piping and fitting ma terials.
CAUTION
Solvent cements for plastic pipe are flammable liq uids and should be kept away from all sources of ignition. Do not use excessive amounts of solvent cement when making joints. Good ventilation should be maintained to reduce fire hazard and to minimize breathing of solvent vapors. Avoid contact of ce ment with skin and eyes.
PIPING AND FITTINGS SPECIFICATIONS
Schedule 40 PVC (Pipe) D1785 Schedule 40 PVC (Cellular Core Pipe) F891
Schedule 40 PVC (Fittings) D2466
Schedule 40 CPVC (Pipe) F441
Schedule 40 CPVC (Fittings) F438
SDR-21 PVC or SDR-26 PVC (Pipe) D2241
SDR-21 CPVC or SDR-26 CPVC (Pipe) F442
Schedule 40 ABS Cellular Core DWV (Pipe) F628
Schedule 40 ABS (Pipe) D1527
Schedule 40 ABS (Fittings) D2468
ABS-DWV (Drain Waste & Vent) (Pipe & Fittings)
PVC-DWV (Drain Waste & Vent) Pipe & Fittings)
PRIMER & SOLVENT CEMENT
PVC & CPVC Primer F656 PVC Solvent Cement D2564
CPVC Solvent Cement F493
ABS Solvent Cement D2235
PVC/CPVC/ABS All Purpose Cement For Fittings & Pipe of the same material
ABS to PVC or CPVC Transition Solvent Cement
CANADA PIPE & FITTING & SOLVENT
CEMENT
PVC & CPVC Pipe and Fittings PVC & CPVC Solvent Cement
ABS to PVC or CPVC Transition Cement
POLYPROPYLENE VENTING SYSTEM
PolyPro by Duravent
TABLE 11
D2661
D2665
ASTM
SPECIFICATION
D2564, D2235, F493
D3138
MARKING
ULCS636
ULC-S636
IMPORTANT
ML193DF exhaust and intake connections are made of PVC. Use PVC primer and solvent cement when using PVC vent pipe. When using ABS vent pipe, use transitional solvent cement to make connections to the PVC fittings in the unit.
Use PVC primer and solvent cement or ABS solvent ce ment meeting ASTM specifications, refer to Table 11. As an alternate, use all purpose cement, to bond ABS, PVC, or CPVC pipe when using fittings and pipe made of the same materials. Use transition solvent cement when bonding ABS to either PVC or CPVC.
Low temperature solvent cement is recommended during cooler weather. Metal or plastic strapping may be used for vent pipe hangers. Uniformly apply a liberal coat of PVC primer for PVC or use a clean dry cloth for ABS to clean in side socket surface of fitting and male end of pipe to depth of fitting socket.
Canadian Applications Only - Pipe, fittings, primer and solvent cement used to vent (exhaust) this appliance must be certified to ULC S636 and supplied by a single manufacturer as part of an approved vent (exhaust) sys tem. In addition, the first three feet of vent pipe from the fur nace flue collar must be accessible for inspection.
Page 18
Page 19
Input Size
045
070
090
110
OUTDOOR TERMINATION USAGE*
TABLE 12
STANDARD CONCENTRIC
Flush
Vent Pipe
Dia. in.
Mount
Kit
51W11
(US)
51W12
2 inch 3 inch 2 inch
22G44 (US)
4
30G28 (CA)
(CA)
2
2-1/2
3
2
2-1/2
3
2
2-1/2
3
3
YES YES
3
YES YES
3
YES YES
3
YES YES
3
YES YES
3
YES YES
3
YES YES YES
3
YES YES YES
3
YES YES YES
2 YES YES YES
2-1/2 YES YES
3 YES YES
Wall Kit Wall Ring Kit
44J40
(US)
4
81J20 (CA)
1
YES
1
YES
1
YES
1
YES
1
YES
1
YES
15F74
1
YES
1
YES
1
YES
1
YES
1
YES
1
YES
1-1/2 inch 2 inch 3 inch
Field
Fabricated
5
YES
5
YES
5
YES
5
YES
5
YES
5
YES
5
YES YES YES
5
YES YES YES
5
YES YES YES
5
YES YES YES
5
YES YES YES
5
YES YES YES
71M80
(US)
4
44W92
(CA)
2
YES
2
YES
2
YES
2
YES
2
YES
2
YES
69M29
(US)
4
44W92
(CA)
60L46 (US)
4
44W93 (CA)
NOTE - Standard Terminations do not include any vent pipe or elbows external to the structure. Any vent pipe or elbows external to the structure must be included in total vent length calculations. See vent length tables.
* Kits must be properly installed according to kit instructions.
1
Requires field-provided outdoor 1-1/2” exhaust accelerator.
2
Concentric kits 71M80 and 44W92 include 1-1/2” outdoor accelerator, when used with 045 and 070 input models.
3
Flush mount kit 51W11 and 51W12 includes 1-1/2 in. outdoor exhaust accelerator, required when used with 045, 070 and 090 input models.
4
Termination kits 30G28, 44W92, 4493 and 81J20 are certified to ULC S636 for use in Canada only.
5
See table 17 for vent accelerator requirements.
Page 19
Page 20
Joint Cementing Procedure
Venting Practices
All cementing of joints should be done according to the specifications outlined in ASTM D 2855.
NOTE - A sheet metal screw may be used to secure the intake pipe to the connector, if desired. Use a drill or self tapping screw to make a pilot hole.
DANGER
DANGER OF EXPLOSION!
Fumes from PVC glue may ignite during system check. Allow fumes to dissipate for at least 5 minutes before placing unit into operation.
1 - Measure and cut vent pipe to desired length.
2 - Debur and chamfer end of pipe, removing any ridges
or rough edges. If end is not chamfered, edge of pipe may remove cement from fitting socket and result in a leaking joint.
3 - Clean and dry surfaces to be joined.
4 - Test fit joint and mark depth of fitting on outside of
pipe.
5 - Uniformly apply a liberal coat of PVC primer for PVC or
use a clean dry cloth for ABS to clean inside socket surface of fitting and male end of pipe to depth of fitting socket.
6 - Promptly apply solvent cement to end of pipe and in
side socket surface of fitting. Cement should be ap plied lightly but uniformly to inside of socket. Take care to keep excess cement out of socket. Apply second coat to end of pipe.
NOTE - Time is critical at this stage. Do not allow prim er to dry before applying cement.
7 - Immediately after applying last coat of cement to pipe,
and while both inside socket surface and end of pipe are wet with cement, forcefully insert end of pipe into socket until it bottoms out. Turn PVC pipe 1/4 turn dur ing assembly (but not after pipe is fully inserted) to dis tribute cement evenly. DO NOT turn ABS or cellular core pipe.
NOTE - Assembly should be completed within 20 sec onds after last application of cement. Hammer blows should not be used when inserting pipe.
8 - After assembly, wipe excess cement from pipe at end
of fitting socket. A properly made joint will show a bead around its entire perimeter. Any gaps may indicate an improper assembly due to insufficient solvent.
9 - Handle joints carefully until completely set.
Piping Suspension Guidelines
SCHEDULE 40
PVC - 5'
all other pipe* - 3'
* See table 11 for allowable pipe.
NOTE - Isolate piping at the point where it exits the outside wall or roof in order to prevent transmission of vibration to the structure.
Wall Thickness Guidelines
24” maximum 3/4” minimum
inside outside
Wall
FIGURE 18
REPLACING FURNACE THAT
CHIMNEY
OR GAS
VENT
(Check sizing
for water
heater only)
FURNACE
(Replaced
by ML193)
If an ML193DF furnace replaces a furnace which was com monly vented with another gas appliance, the size of the ex isting vent pipe for that gas appliance must be checked. Without the heat of the original furnace flue products, the existing vent pipe is probably oversized for the single water heater or other appliance. The vent should be checked for proper draw with the remaining appliance.
WAS PART OF A COMMON
VENT SYSTEM
WATER
HEATER
OPENINGS
(To Adjacent
Room)
FIGURE 19
Page 20
Page 21
1. In areas where piping penetrates joists or interior walls, hole must be large enough to allow clearance on all sides of pipe through center of hole using a hanger.
2. When furnace is installed in a residence where unit is shut down for an extended period of time, such as a vacation home, make provisions for draining conden sate collection trap and lines.
Exhaust Piping (Figures 21 and 22)
Route piping to outside of structure. Continue with installa tion following instructions given in piping termination sec tion.
CAUTION
Do not discharge exhaust into an existing stack or stack that also serves another gas appliance. If verti cal discharge through an existing unused stack is re quired, insert PVC pipe inside the stack until the end is even with the top or outlet end of the metal stack.
CAUTION
The exhaust vent pipe operates under positive pres sure and must be completely sealed to prevent leak age of combustion products into the living space.
Vent Piping Guidelines
NOTE - Lennox has approved the use of DuraVent® manu factured vent pipe and terminations as an option to PVC. When using the PolyPro vent pipe requirements stated in the unit installation in struction – minimum & maximum vent lengths, termination clearances, etc. – apply and must be followed. Follow the instructions provided with PoyPro by DuraVent venting system for assembly or if requirements are more restrict ive. The PolyPro by Duravent venting system must also fol low the uninsulated and unconditioned space criteria listed in table 16.
®
by DuraVent venting system the
The ML193DF can be installed as either a Non-Direct Vent or a Direct Vent gas central furnace.
NOTE - In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors. In Non-Direct Vent installations, combustion air is taken from indoors or ventilated attic or crawlspace and flue gases are discharged outdoors.
Intake and exhaust pipe sizing -- Size pipe according to
tables 13 and 14. Count all elbows inside and outside the home. Table 13 lists the minimum vent pipe lengths per mitted. Table 14 lists the maximum pipe lengths permitted.
MINIMUM VENT PIPE LENGTHS
ML193DF
MODEL
045, 070, 090, 110
*Any approved termination may be added to the minimum length listed.
Regardless of the diameter of pipe used, the standard roof and wall terminations described in section Exhaust Piping Terminations should be used. Exhaust vent termination pipe is sized to optimize the velocity of the exhaust gas as it exits the termination. Refer to table 17.
In some applications which permit the use of several differ ent sizes of vent pipe, a combination vent pipe may be used. Contact Lennox' Application Department for assis tance in sizing vent pipe in these applications.
TABLE 13
MIN. VENT LENGTH*
15 ft. or
5 ft plus 2 elbows or
10 ft plus 1 elbow
IMPORTANT
Do not use screens or perforated metal in exhaust or intake terminations. Doing so will cause freeze-ups and may block the terminations.
Use the following steps to correctly size vent pipe diameter.
Page 21
Page 22
Piping Size Process
What is the
furnace capacity?
1
045, 070, 090 or
110?
Which style termination
2
3
4
being used?
Standard or concentric?
See table 12.
Which needs
most elbows?
Intake or
exhaust?
How many elbows? Count all elbows inside and outside house.
NOTE - It is acceptable to use any pipe size which fits within the guidelines allowed in table 14.
NOTE ­toward unit. A minimum of 1/4” (6mm) drop for each 12” (305mm) of horizontal run is mandatory for drainage.
NOTE - Exhaust pipe MUST be glued to furnace exhaust fittings.
NOTE - Exhaust piping should be checked carefully to make sure there are no sags or low spots.
All horizontal runs of exhaust pipe must slope back
Desired pipe size?
5
6
7
2”, 2-1/2”, 3”
What is the altitude of the furnace installation?
Use table 14 or 15 to find max intake or exhaust pipe length. Includes all vent pipe and elbows inside and outside the house.
FIGURE 20
Page 22
Page 23
Maximum Allowable Intake or Exhaust Vent Length in Feet
TABLE 14
*Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust must be same pipe size. NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.
Standard Termination at Elevation 0 - 10,000 ft.
Number
Of 90°
Elbows
Used
1 61 46 24
2 56 41 19 95 75 38 122 122 103 103
3 51 36 14 90 70 33 117 117 98 98
4 46 31
5 41 26 80 60 23 107 107 88 88
6 36 21 75 55 18 102 102 83 83
7 31 16 70 50 13 97 97 78 78
8 26 11 65 45
9 21
10 16 55 35 82 82 63 63
Number
Of 90°
Elbows
Used
1 53 38 22
2 48 33 17 85 65 34 106 106 99 99
3 43 28 12 80 60 29 101 101 94 94
4 38 23
5 33 18 70 50 19 91 91 84 84
6 28 13 65 45 14 86 86 79 79
7 23
8 18 55 35 76 76 69 69
9 13 50 30 71 71 64 64
10 n/a 45 25 66 66 59 59
045 070 090 110 045 070 090 110 045 070 090 110
045 070 090 110 045 070 090 110 045 070 090 110
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
100 80 43
85 65 28 112 112 93 93
n/a
n/a
n/a
Concentric Termination Elevation 0 - 10,000 ft.
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
n/a
n/a
n/a
60 40 87 87 68 68
90 70 39
75 55 24 96 96 89 89
60 40
n/a
n/a
n/a
n/a
127 127 108 108
92 92 73 73
111 111 104 104
81 81 74 74
Maximum Allowable Exhaust Vent Lengths With Furnace Installed in a Closet or Basement Using Ventilated
NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.
Number
Of 90°
Elbows
Used
1 51 36 14
2 46 31 9 80 60 23 102 102 83 83
3 41 26 4 75 55 18 97 97 78 78
4 36 21
5 31 16 65 45 8 87 87 68 68
6 26 11 60 40 3 82 82 63 63
7 21 6 55 35
8 16 1 50 30 72 72 53 53
9 11
10 6 40 20 62 62 43 43
045 070 090 110 045 070 090 110 045 070 090 110
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
n/a
n/a
TABLE 15
Attic or Crawl Space For Intake Air in Feet
Standard Termination at Elevation 0 - 10,000 ft.
85 65 28
70 50 13 92 92 73 73
n/a
45 25 67 67 48 48
n/a
n/a
Page 23
107 107 88 88
77 77 58 58
Page 24
TYPICAL EXHAUST PIPE CONNECTIONS
Pipe size determined in table 14.
*2”
2”
2”
or
DO NOT transition from smaller
to larger pipe size in horizontal
runs of exhaust pipe.
2”
2”
3”
TRANSITION
* When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible.
NOTE − Exhaust pipe and intake pipe must be the same diameter.
FIGURE 21
TYPICAL INTAKE PIPE CONNECTIONS
2”
INTAKE
EXHAUST
TOP VIEW
Pipe size determined in table 14.
2”
3”
TRANSITION
*2”
* When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible.
NOTE − Intake pipe and exhaust pipe must be the same diameter.
FIGURE 22
Intake Piping
The ML193DF furnace may be installed in either direct vent or non-direct vent applications. In non-direct vent
applications, when intake air will be drawn into the furnace from the surrounding space, the indoor air quality must be considered. Guidelines listed in Combustion, Dilution and Ventilation Air section must be followed.
2”
2”
*2”
2”
or
TRANSITION
*2”
2”
3”
INTAKE
TOP VIEW
Follow the next two steps when installing the unit in Direct Vent applications, where combustion air is taken from outdoors and flue gases are discharged outdoors. The provided air intake screen must not be used in direct vent applications (outdoors).
1 - Use cement to secure the intake pipe to the inlet air
connector.
EXHAUST
Page 24
Page 25
2 - Route piping to outside of structure. Continue with
e
installation following instructions given in general guide lines for piping terminations and intake and ex haust piping terminations for direct vent sections. Re fer to table
14 for pipe sizes.
TYPICAL AIR INTAKE PIPE CONNECTIONS
NON−DIRECT VENT APPLICATIONS
AIR
INTAKE
SCREEN
(Provided)
(Inlet Air from Ventilated Attic and Outlet Air to Outside)
Roof T erminated
Exhaust Pipe
EQUIPMENT IN CONFINED SPACE
Ventilation Louvers
Inlet Air
(Minimum
12 in.(305mm) Abov
attic floor)
*Intake Debris
Screen
(Provided)
Furnace
* See table 15 for maximum vent lengths
NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch per 4,000 Btu (645mm hour of the total input rating of all equipment in the enclosure.
2
per 1.17kW) per
FIGURE 24
NOTE - Air intake screen and elbow may be rotated, so that screen may be positioned to face forward or to either side.
FIGURE 23
Follow the next two steps when installing the unit in Non‐ Direct Vent applications where combustion air is taken from indoors and flue gases are discharged outdoors.
1 - Use field-provided materials and the factory-provided
air intake screen to route the intake piping as shown in figure 23. Maintain a minimum clearance of 3” (76mm) around the air intake opening. The air intake opening (with the protective screen) should always be directed forward, or sideways.
2 - If intake air is drawn from a ventilated attic (figure 24)
or ventilated crawlspace (figure 25) the exhaust vent length must not exceed those listed in table 15. If 3” di ameter pipe is used, reduce to 2” diameter pipe at the termination point to accommodate the debris screen.
3 - Use cement to secure the intake pipe to the connector,
if desired.
CAUTION
If this unit is being installed in an application with combustion air coming in from a space serviced by an exhaust fan, power exhaust fan, or other device which may create a negative pressure in the space, take care when sizing the inlet air opening. The in let air opening must be sized to accommodate the maximum volume of exhausted air as well as the maximum volume of combustion air required for all gas appliances serviced by this space.
(Inlet Air from Ventilated Crawlspace and Outlet Air to Outside)
Roof T erminated
Exhaust Pipe
Ventilation
Louvers
(Crawl space)
(Field Provided)
EQUIPMENT IN CONFINED SPACE
Furnace
Coupling or 3 in. to 2 in.
Transition
12 in.(305mm)
*Intake Debris Screen Provided)
Inlet Air
(Minimum
Above crawl
space floor)
* See table 15 for maximum vent lengths
NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch per 4,000 Btu (645mm hour of the total input rating of all equipment in the enclosure.
2
per 1.17kW) per
FIGURE 25
General Guidelines for Vent Terminations
In Non‐Direct Vent applications, combustion air is taken from indoors and the flue gases are discharged to the out doors. The ML193DF is then classified as a non‐direct vent, Category IV gas furnace.
In Direct Vent applications, combustion air is taken from outdoors and the flue gases are discharged to the out doors. The ML193DF is then classified as a direct vent, Category IV gas furnace.
In both Non‐Direct Vent and Direct Vent applications, the vent termination is limited by local building codes. In the ab sence of local codes, refer to the current National Fuel Gas Code ANSI Z223-1/NFPA 54 in U.S.A., and current CSA­B149 Natural Gas and Propane Installation Codes in Can ada for details.
Page 25
Page 26
Position termination according to location given in figure 27 or 28. In addition, position termination so it is free from any obstructions and 12” above the average snow accumula tion.
At vent termination, care must be taken to maintain protective coatings over building materials (prolonged exposure to exhaust condensate can destroy protective coatings). It is recommended that the exhaust outlet not be located within 6 feet (1.8m) of a condensing unit because the condensate can damage the painted coating.
NOTE - See table 16 for maximum allowed exhaust pipe length without insulation in unconditioned space during winter design temperatures below 32°F (0°C). If required exhaust pipe should be insulated with 1/2” (13mm) Arma flex or equivalent. In extreme cold climate areas, 3/4” (19mm) Armaflex or equivalent may be necessary. Insula tion must be protected from deterioration. Armaflex with UV protection is permissable. Basements or other en
closed areas that are not exposed to the outdoor ambient temperature and are above 32 degrees F (0°C) are to be considered conditioned spaces.
IMPORTANT
Do not use screens or perforated metal in exhaust terminations. Doing so will cause freeze-ups and may block the terminations.
IMPORTANT
For Canadian Installations Only: In accordance to CSA International B149 installation codes, the minimum allowed distance between the combustion air intake inlet and the exhaust outlet of other appliances shall not be less than 12 inches (305mm).
Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation In Unconditioned Space For
TABLE 16
Winter Design Temperatures Single - Stage High Efficiency Furnace
Winter Design
Temperatures
(-18 to -29)
1Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.
2
Poly-Propylene vent pipe (PP)
NOTE - Maximum uninsulated vent lengths listed may include the termination(vent pipe exterior to the structure) and cannot exceed 5 linear feet or the maximum allowable intake or exhaust vent length listed in table 14 or 15 which ever is less.
NOTE - If insulation is required in an unconditioned space, it must be located on the pipe closest to the furnace. See figure26.
32 to 21
(0 to -6)
20 to 1
(-7 to -17)
0 to -20
1
°F (°C)
Vent Pipe
Diameter
2 in. 26 24 44 41 44 44 24 24 N/A N/A
2-1/2 in. 18 N/A 32 N/A 50 N/A 58 N/A N/A N/A
3 in. 14 12 26 23 38 33 55 49 60 53
2 in 16 15 28 26 40 37 24 24 N/A N/A
2-1/2 in. 12 N/A 20 N/A 30 N/A 44 N/A N/A N/A
3 in. 9 8 16 14 26 23 32 28 40 35
2 in. 10 9 20 18 30 28 24 24 N/A N/A
2-1/2 in. 8 N/A 14 N/A 20 N/A 32 N/A N/A N/A
3 in. 4 3 10 8 16 14 26 23 30 26
045 070 090 110 135
PVC
2
PP PVC
Unit Input Size
2
PP PVC
2
PP PVC
2
PP PVC
2
PP
Conditioned
Space
Conditioned
Space
FIGURE 26
Page 26
Pipe Insulation
Unconditioned
Space
Exhaust
Pipe
Intake
Pipe
Page 27
VENT TERMINATION CLEARANCES
FOR NON-DIRECT VENT INSTALLATIONS IN THE USA AND CANADA
INSIDE CORNER
DETAIL
G
D
A
E
B
L
C
Fixed
F
Closed
Operable
B
Operable
B
B
VENT TERMINAL
AIR SUPPLY INLET
US Installations
A =
Clearance above grade, veranda,
porch, deck or balcony
B =
Clearance to window or
door that may be opened
C =
Clearance to permanently
closed window
D =
Vertical clearance to ventilated soffit
located above the terminal within a
12 inches (305mm) or 12 in. (305mm)
above average snow accumulation.
4 feet (1.2 m) below or to side of opening;
1 foot (30cm) above opening
* 12”
* Equal to or greater than soffit depth.
horizontal distance of 2 feet (610 mm)
from the center line of the terminal
E =
F =
G =
H =
Clearance to unventilated soffit
Clearance to outside corner
Clearance to inside corner
Clearance to each side of center line ex
tended above meter / regulator assembly
I =
Clearance to service regulator
vent outlet
J =
Clearance to non-mechanical air
supply inlet to building or the com
bustion air inlet to any other ap
* Equal to or greater than soffit depth.
* No minimum to outside corner * No minimum to outside corner
**
3 feet (.9m) within a height 15 feet (4.5m)
*
above the meter / regulator assembly
* 3 feet (.9m)
4 feet (1.2 m) below or to side of opening;
1 foot (30 cm) above opening
pliance
K =
L =
Clearance to mechanical air sup
ply inlet
Clearance above paved sidewalk or
3 feet (.9m) above if within 10 feet
(3m) horizontally
7 feet (2.1m)†
paved driveway located on public property
M =
Clearance under veranda, porch, deck or balcony
1
In accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code
2
In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code † A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Lennox recommends avoiding this location if possible.
*12 inches (305mm)‡
FIGURE 27
H
B
Fixed
Closed
A
J
I
M
AREA WHERE TERMINAL IS NOT PERMITTED
1
Canadian Installations
12 inches (305mm) or 12 in. (305mm)
above average snow accumulation.
6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
for appliances > 100,000 Btuh (30kw)
* 12”
* Equal to or greater than soffit depth.
* Equal to or greater than soffit depth.
3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
3 feet (.9m)
6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
for appliances > 100,000 Btuh (30kw)
6 feet (1.8m)
7 feet (2.1m)†
12 inches (305mm)‡
*For clearances not specified in ANSI Z223.1/NFPA 54 or CSA B149.1, clearance will be in accordance with local installation codes and the requirements of the gas supplier and these instal lation instructions.”
K
2
Page 27
Page 28
VENT TERMINATION CLEARANCES
FOR DIRECT VENT INSTALLATIONS IN THE USA AND CANADA
INSIDE CORNER
DETAIL
G
D
A
E
B
L
C
Fixed
F
Closed
Operable
B
Operable
B
B
VENT TERMINAL
AIR SUPPLY INLET
US Installations
A =
B =
Clearance above grade, veranda,
porch, deck or balcony
Clearance to window or
door that may be opened
12 inches (305mm) or 12 in. (305mm)
above average snow accumulation.
6 inches (152mm) for appliances <10,000
Btuh (3kw), 9 inches (228mm) for ap
pliances > 10,000 Btuh (3kw) and <50,000
Btuh (15 kw), 12 inches (305mm) for ap
pliances > 50,000 Btuh (15kw)
C =
Clearance to permanently
* 12”
closed window
D =
Vertical clearance to ventilated soffit
located above the terminal within a
* Equal to or greater than soffit depth
horizontal distance of 2 feet (610mm)
from the center line of the terminal
E =
F =
G =
H =
Clearance to unventilated soffit
Clearance to outside corner
Clearance to inside corner
Clearance to each side of center line ex
tended above meter / regulator assembly
I =
Clearance to service regulator
vent outlet
J =
Clearance to non-mechanical air
supply inlet to building or the com
bustion air inlet to any other ap
pliance
* Equal to or greater than soffit depth * Equal to or greater than soffit depth
* No minimum to outside corner
*
3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
3 feet (.9m)
*
6 inches (152mm) for appliances <10,000
Btuh (3kw), 9 inches (228mm) for ap
pliances > 10,000 Btuh (3kw) and <50,000
Btuh (15 kw), 12 inches (305mm) for ap
pliances > 50,000 Btuh (15kw)
K =
L =
M =
1
In accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code
2
In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code
† A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Lennox recommends avoiding this location if possible.
Clearance to mechanical air sup
ply inlet
Clearance above paved sidewalk or
paved driveway located on public property
Clearance under veranda, porch, deck or balcony
3 feet (.9m) above if within 10 feet
(3m) horizontally
* 7 feet (2.1m)
*12 inches (305mm)‡
FIGURE 28
H
B
Fixed
Closed
A
J
I
M
K
AREA WHERE TERMINAL IS NOT PERMITTED
1
Canadian Installations
2
12 inches (305mm) or 12 in. (305mm)
above average snow accumulation.
6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
for appliances > 100,000 Btuh (30kw)
* 12”
* Equal to or greater than soffit depth* Equal to or greater than soffit depth
* No minimum to outside corner
*
3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
3 feet (.9m)
6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
for appliances > 100,000 Btuh (30kw)
6 feet (1.8m)
7 feet (2.1m)†
12 inches (305mm)‡
*For clearances not specified in ANSI Z223.1/NFPA 54 or CSA B149.1, clearance will be in accordance with local installation codes and the requirements of the gas supplier and these installation instructions.”
Page 28
Page 29
Details of Intake and Exhaust Piping Terminations for Direct Vent Installations
NOTE - In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged to outdoors.
NOTE - Flue gas may be slightly acidic and may adversely affect some building materials. If any vent termination is used and the flue gasses may impinge on the building ma terial, a corrosion-resistant shield (minimum 24 inches square) should be used to protect the wall surface. If the optional tee is used, the protective shield is recommended. The shield should be constructed using wood, plastic, sheet metal or other suitable material. All seams, joints, cracks, etc. in the affected area should be sealed using an appropriate sealant. See figure 36.
Intake and exhaust pipes may be routed either horizontally through an outside wall or vertically through the roof. In at tic or closet installations, vertical termination through the roof is preferred. Figures 31 through 37 show typical ter minations.
1. Intake and exhaust terminations are not required to be in the same pressure zone. You may exit the intake on one side of the structure and the exhaust on another side (figure 29). You may exit the exhaust out the roof and the intake out the side of the structure (figure 30).
2. Intake and exhaust pipes should be placed as close together as possible at termination end (refer to il lustrations). Maximum separation is 3” (76mm) on roof terminations and 6” (152mm) on side wall termina tions.
NOTE - When venting in different pressure zones, the maximum separation requirement of intake and ex haust pipe DOES NOT apply.
3. On roof terminations, the intake piping should termi nate straight down using two 90° elbows (See figure
31).
4. Exhaust piping must terminate straight out or up as shown. A reducer may be required on the exhaust pip ing at the point where it exits the structure to improve the velocity of exhaust away from the intake piping. See table 17.
TABLE 17
EXHAUST PIPE TERMINATION SIZE REDUCTION
ML193
MODEL
*045 and *070
*090 2” (51mm)
110
*ML193DF-045, -070 and -090 units with the flush-mount termination must use the 1-1/2”accelerator supplied with the kit.
Exhaust Pipe Size
2” (51mm), 2-1/2” (64mm),
3” (76mm)
3” (76mm)
Termination
Pipe Size
1-1/2” (38mm)
2” (51mm)
5. On field-supplied terminations for side wall exit, ex haust piping may extend a maximum of 12 inches (305mm) for 2” PVC and 20 inches (508mm) for 3” (76mm) PVC beyond the outside wall. Intake piping should be as short as possible. See figure 36.
6. On field supplied terminations, a minimum distance between the end of the exhaust pipe and the end of the intake pipe without a termination elbow is 8” and a minimum distance of 6” with a termination elbow. See figure 36.
NOTE - Care must be taken to avoid recirculation of exhaust back into intake pipe.
Exiting Exhaust and Intake Vent
(different pressure zones)
Exhaust
Pipe
Furnace
Inlet Air
(Minimum 12 in.
305 MM) above
grade or snow
accumulation
FIGURE 29
Exiting Exhaust and Intake Vent
(different pressure zones)
Roof T
erminated
Exhaust Pipe
Inlet Air
Furnace
(Minimum 12 in.
305 MM) above
grade or snow
accumulation
FIGURE 30
Inches(mm)
8” (203mm) MIN
12” (305mm) ABOVE
AVERAGE SNOW
ACCUMULATION
3” (76mm) OR
2” (51mm) PVC
PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES
DIRECT VENT ROOF TERMINATION KIT
3”(76mm) MAX.
(15F75 or 44J41)
SIZE TERMINATION
PIPE PER TABLE 17.
UNCONDITIONED
ATTIC SPACE
1/2” (13mm) FOAM
INSULATION IN
UNCONDITIONED
SPACE
FIGURE 31
Page 29
Page 30
7. If intake and exhaust piping must be run up a side wall to position above snow accumulation or other ob structions, piping must be supported. At least one bracket must be used within 6” from the top of the el bow and then every 24” (610mm) as shown in figure 36, to prevent any movement in any direction. When exhaust and intake piping must be run up an outside wall, the exhaust piping must be terminated with pipe sized per table 17.The intake piping may be equipped with a 90° elbow turndown. Using turndown will add 5 feet (1.5m) to the equivalent length of the pipe.
8. A multiple furnace installation may use a group of up to four terminations assembled together horizontally, as shown in figure 34.
1-1/2” (38mm) accelerator
provided on 71M80 & 44W92
12” (305mm)
Minimum
Above Average
Snow
Accumulation
kits for ML193DF045P36B- &
INTAKE
070P36B
FLASHING
(Not Furnished)
EXHAUST
VENT
INTAKE
AIR
Inches (mm)
optional intake elbow
OPTIONAL VENT TERMINATION FOR MULTIPLE UNIT
INSTALLATION OF DIRECT VENT WALL TERMINATION KIT
5”
(127mm)
18” MAX.
(457mm)
EXHAUST VENT
Side View
(30G28 or 81J20)
INTAKE
AIR
12”
(305mm)
5-1/2”
(140mm)
Front View
12” (305mm) Min.
above grade or
average snow ac
cumulation.
FIGURE 34
2” EXTENSION FOR 2” PVC PIPE1” EXTENSION FOR 3” PVC PIPE
4''
FURNACE EXHAUST
PIPE
SHEET METAL STRAP
(Clamp and sheet metal strap
must be field installed to support
CLAMP
DIRECT VENT CONCENTRIC ROOFTOP TERMINATION
71M80, 69M29 or 60L46 (US)
41W92 or 41W93 (Canada)
the weight of the termination kit.)
FIELD-PROVIDED
REDUCER MAY BE REQUIRED
TO ADAPT LARGER VENT
PIPE SIZE TO TERMINATION
FIGURE 32
1-1/2” (38mm) accelerator
FIELD-PROVIDED
REDUCER MAY BE
REQUIRED TO ADAPT
LARGER VENT PIPE
SIZE TO TERMINA
TION
EXHAUST
AIR
INTAKE
AIR
DIRECT VENT CONCENTRIC WALL TERMINATION
OUTSIDE
WALL
CLAMP
(Not Furnished)
71M80, 69M29 or 60L46 (US)
41W92 or 41W93 (Canada)
provided on 71M80 &
44W92 kits for
ML193DF045P36B- &
070P36B
INTAKE
AIR
EXHAUST
AIR
12” (305mm) Min.
INTAKE
AIR
above grade or
average snow ac
cumulation.
GRADE
FIGURE 33
FURNACE
INTAKE
PIPE
GLUE EXHAUST
END FLUSH INTO
TERMINATION
FLAT SIDE
1-1/2” ACCELERATOR
(all -45, -070 and -090 units)
FLUSH-MOUNT SIDE WALL TERMINATION
51W11 (US) or 51W12 (Canada)
FIGURE 35
Page 30
Page 31
NOTE − FIELD−PROVIDED
REQUIRED TO ADAPT
LARGER VENT PIPE SIZE
* WALL
SUPPORT
C1
REDUCER MAY BE
TO TERMINATION
C1
A
E
D
B
STRAIGHT
APPPLICATION
D
B
A
EXTENDED
APPLICATION
FIELD FABRICATED WALL TERMINATION
A− Minimum clearance
above grade or average
snow accumulation
B− Maximum horizontal separation between
intake and exhaust
C1 -Minimum from end of
exhaust to inlet of intake
C2 -Minimum from end of
exhaust to inlet of intake
D− Maximum exhaust
pipe length
E− Maximum wall support
distance from top of each
pipe (intake/exhaust)
D
B
See venting table 14 for maximum venting lengths with this arrangement.
* Use wall support every 24” (610 mm). Use two wall supports if extension is greater than 24” (610 mm) but less than 48” (1219 mm). NOTE − One wall support must be within 6” (152 mm) from top of each pipe (intake and exhaust) to prevent movement in any direction.
Intake Elbow
C2
D
B
C2
A
E
A
2” (51mm)
Vent Pipe
12” (305 mm)
12” (305 mm)
6” (152 mm)
3” (76mm)
Vent Pipe
12” (305 mm)
6” (152 mm)6” (152 mm)
8” (203 mm)8” (203 mm)
6” (152 mm)6” (152 mm)
20” (508 mm)
6” (152 mm)
ALTERNATE TERMINATIONS (TEE & FORTY−FIVE DEGREE ELBOWS ONLY)
2” (51MM)
B
D
1
C
2
A
D
E
B
C
2
A
1
12”
1
The exhaust termination tee should be connected to the 2” or 3” PVC flue pipe as shown in the illustration. Do not use an accelerator in applications that include an exhaust termination tee. The accelerator is not required.
2
As required. Flue gas may be acidic and may adversely affect some building materials. If a side wall vent
termination is used and flue gases will impinge on the building materials, a corrosion−resistant shield (24 inches square) should be used to protect the wall surface. If optional tee is used, the protective shield is recommended. The shield should be constructed using wood, sheet metal or other suitable material. All seams, joints, cracks, etc. in affected area, should be sealed using an appropriate sealant.
3
Exhaust pipe 45° elbow can be rotated to the side away from the combustion air inlet to direct exhaust away from adjacent property. The exhaust must never be directed toward the combustion air inlet.
B
Intake Elbow
Intake and Exhaust
Intake
C
A
Front View of
Exhaust
D
Exhaust
3
A− Clearance above
grade or average snow
accumulation
B− Horizontal
separation between
intake and exhaust
C− Minimum from
end of exhaust to
inlet of intake
D− Exhaust pipe length
E− Wall support distance
from top of each pipe
(intake/exhaust)
Vent Pipe
12” (305 mm) Min. 12” (305 mm) Min.
6” (152 mm) Min. 24” (610 mm) Max.
9” (227 mm) Min.
12” (305 mm) Min. 16” (405 mm) Max.
6” (152 mm) Max.
3” (76MM)
Vent Pipe
6” (152 mm) Min. 24” (610 mm) Max.
9” (227 mm) Min. 12” (305 mm) Min.
20” (508 mm) Max.
6” (152 mm) Max.
FIGURE 36
Page 31
Page 32
ML193DF DIRECT VENT APPLICATION
USING EXISTING CHIMNEY
8” - 12”
(203mm - 305mm)
Minimum 12” (305MM)
above chimney top
plate or average snow
accumulation
*SIZE TERMINATION PIPE PER TABLE 17.
NOTE - Do not discharge exhaust gases directly into any chimney or vent stack. If ver tical discharge through an existing unused chimney or stack is required, insert piping inside chimney until the pipe open end is above top of chimney and terminate as illus trated. In any exterior portion of chimney, the exhaust vent must be insulated.
INTAKE PIPE
INSULATION (optional)
SHEET
METAL TOP
PLATE
INSULATE
TO FORM
SEAL
3” - 8” (76mm­203mm)
STRAIGHT-CUT OR
ANGLE-CUT IN DIRECTION
OF ROOF SLOPE *
EXHAUST VENT
1/2” (13mm)
WEATHERPROOF
INSULATION
SHOULDER OF FITTINGS
PROVIDE SUPPORT
OF PIPE ON TOP PLATE
3” - 8” (76mm­203mm)
ALTERNATE INTAKE PIPE
EXTERIOR
PORTION OF
CHIMNEY
FIGURE 37 Details of Exhaust Piping Terminations for Non‐Direct Vent Applications
Exhaust pipes may be routed either horizontally through an outside wall or vertically through the roof. In attic or closet installations, vertical termination through the roof is pre ferred. Figures 38 through 39 show typical terminations.
1. Exhaust piping must terminate straight out or up as
shown. The termination pipe must be sized as listed in table 17.The specified pipe size ensures proper ve locity required to move the exhaust gases away from the building.
SIZE TERMINATION
PIPE PER TABLE
12” (305mm)
ABOVE AVE.
SNOW
ACCUMULATION
1/2” (13mm) FOAM
INSULATION
17.
2. On field supplied terminations for side wall exit, ex haust piping may extend a maximum of 12 inches (305mm) for 2” PVC and 20 inches (508mm) for 3” (76mm) PVC beyond the outside wall.
3. If exhaust piping must be run up a side wall to position above snow accumulation or other obstructions, pip ing must be supported every 24 inches (610mm). When exhaust piping must be run up an outside wall, any reduction in exhaust pipe size must be done after the final elbow.
4. Distance between exhaust pipe terminations on mul tiple furnaces must meet local codes.
ML193DF NON-DIRECT VENT APPLICATION
USING EXISTING CHIMNEY
SIZE TERMINATION
PIPE PER TABLE 17.
3” - 8”
(76mm-
Minimum 12” (305MM)
above chimney top
plate or average snow
accumulation
METAL TOP
INSULATE TO FORM
SEAL
NOTE - Do not discharge exhaust gases directly into any chimney or vent stack. If ver tical discharge through an existing unused chimney or stack is required, insert piping inside chimney until the pipe open end is above top of chimney and terminate as illus trated. In any exterior portion of chimney, the exhaust vent must be insulated.
203mm)
SHEET
PLATE
STRAIGHT-CUT OR
ANGLE-CUT IN DIRECTION
OF ROOF SLOPE
EXHAUST VENT
1/2” (13mm)
WEATHERPROOF
INSULATION
SHOULDER OF FITTINGS
PROVIDE SUPPORT
OF PIPE ON TOP PLATE
3” - 8”
(76mm-
203mm)
EXTERIOR
PORTION OF
CHIMNEY
FIGURE 39
3” (76mm) OR
2” (51mm) PVC
PROVIDE SUPPORT
FOR EXHAUST LINES
NON-DIRECT VENT ROOF TERMINATION KIT
(15F75 or 44J41)
FIGURE 38
UNCONDITIONED
ATTIC SPACE
Page 32
Page 33
Condensate Piping
This unit is designed for either right‐ or left‐side exit of con densate piping. Refer to figures 40 and 42 for condensate trap locations.
NOTE - If necessary the condensate trap may be installed up to 5’ away from the furnace. Use PVC pipe to connect trap to furnace condensate outlet. Piping from furnace must slope down a minimum of 1/4” per ft. toward trap.
CONDENSATE TRAP AND PLUG LOCATIONS
4 - Install drain trap using appropriate PVC fittings, glue
all joints. Glue the provided drain trap as shown in fig ures 46 and 47. Route the condensate line to an open drain.
5 - Figure 44 shows the furnace and evaporator coil using
a separate drain. If necessary, the condensate line from the furnace and evaporator coil can drain togeth er. See figures 45 and 43. The field provided vent must be a minimum 1” to a maximum 2” length above the condensate drain outlet connection.
NOTE - If necessary the condensate trap may be installed up to 5 feet away from the furnace. Piping from furnace must slope down a minimum of 1/4” per ft. toward trap.
NOTE - Appropriately sized tubing and barbed fitting may be used for condensate drain. Attach to the drain on the trap using a hose clamp. See figure 41.
Trap
(same on
right side)
1-1/2 in.
FIGURE 40
1 - Determine which side condensate piping will exit the
unit, location of trap, field-provided fittings and length of PVC pipe required to reach available drain.
2 - For furnaces with a 1/2” drain connection use a 3/8 al
len wrench and remove plug (figure 40) from the cold end header box at the appropriate location on the side of the unit. Install field-provided 1/2 NPT male fitting into cold end header box. For furnaces with a 3/4” drain connection use a large flat head screw driver or a 1/2” drive socket extension and remove plug. Install provided 3/4 NPT street elbow fitting into cold end header box. Use Teflon tape or appropriate pipe dope.
3 - Install the cap over the clean out opening at the base
of the trap. Secure with clamp. See figures 46 and 47.
Plug
(same on left
side)
Field Provided Drain Components
Elbow
Barbed Fitting
Tubing
Hose Clamp
FIGURE 41
6 - If unit will be started immediately upon completion of
installation, prime trap per procedure outlined in Unit Start-Up section.
Condensate line must slope downward away from the trap to drain. If drain level is above condensate trap, condensate pump must be used. Condensate drain line should be routed within the conditioned space to avoid freezing of condensate and blockage of drain line. If this is not possible, a heat cable kit may be used on the condensate trap and line. Heat cable kit is avail able from Lennox in various lengths; 6 ft. (1.8m) - kit no. 26K68; 24 ft. (7.3m) - kit no. 26K69; and 50 ft. (15.2m) - kit no. 26K70.
CAUTION
Do not use copper tubing or existing copper condensate lines for drain line.
Page 33
Page 34
CONDENSATE TRAP LOCATION
(shown with right side exit of condensation)
Trap can be installed a maxi mum of 5ft. from furnace (*PVC only)
Field Provided Vent
1” min. 2” max. above
condensate drain.
1” min.
2” max.
5’ max.
ML193DF with Evaporator Coil
Using a Separate Drain
Field Provided Vent
1” min. 2” max. above
condensate drain.
Condensate Drain
Connection
Evaporator Drain Line
(vent required)
to drain
*Piping from furnace must slope down a
minimum 1/4” per ft. toward trap
FIGURE 42
Condensate Trap With Optional Overflow Switch
From Evaporator Coil
Optional
Field Provided Vent
1” min. 2” max. above
condensate drain.
FurnaceCondensate
Drain
Connection
Drain
FIGURE 44
IMPORTANT
When combining the furnace and evaporator coil drains together, the A/C condensate drain outlet must be vented to relieve pressure in or der for the furnace pressure switch to operate properly.
ML193DF with Evaporator Coil Using a Common Drain
Field Provided Vent
1” min. 2” max. above
condensate drain.
Condensate Drain
Connection
FIGURE 43
Evaporator Drain Line
(vent required)
FIGURE 45
Page 34
Page 35
it
TRAP / DRAIN ASSEMBLY USING 1/2” PVC OR 3/4” PVC
COLD END HEADER BOX WITH 3/4” DRAIN CONNECTION
Optional Condensate Drain Connection
Adapter 3/4 inch slip X
3/4 inch mpt (not furnished)
90° Street Elbow 3/4 inch PVC (not furnished)
Condensate Drain
Connection In Unit
90° Street Elbow 3/4 inch PVC ( furnished)
To
Trap
OptionalDrainPipingFromTrap
Drain Assembly for 1/2 inch Drain Pipe
1/2 inch PVC Pipe
(Not Furnished)
90° Elbow
1/2 inch PVC
(Not Furnished)
To
Drain
Drain Assembly for 3/4 inch Drain Pipe
1 (25mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit
Elbow 3/4 inch PVC
90°
(Not Furnished)
1/2 inch PVC Pipe
(Not Furnished)
Adapter 3/4 inch slip X
3/4 inch mpt (not furnished)
V
ent
5 Feet
Maximum
3/4 inch PVC Pipe
(Not Furnished)
Coupling 3/4 inch slip X slip
(Not Furnished)
Drain Trap
Assembly
(Furnished)
Condensate Drain
Connection In Un
90° Elbow
3/4 inch PVC
(Not Furnished)
To
Drain
DrainTrapAssembly
(Furnished)
7
(178)
Drain Trap
Clean Out
90° Elbow
3/4 inch PVC
(Not Furnished)
T
o
Coupling 3/4 inch slip X slip
Drain
DrainTrap Assembly with 1/2 inch Piping 1 (25 mm) Min. 2 (50 mm) Max. Above Top
Of Condensate Drain Connection In Unit
(Not Furnished)
Vent
1/2 inch
Condensate Drain
Connection In Unit
To
Drain
DrainTrap Assembly with 3/4 inch Piping
1 (25 mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit
Vent
3/4 inch
Condensate Drain
Connection In Unit
To
Drain
FIGURE 46
Page 35
Page 36
TRAP / DRAIN ASSEMBLY USING 1/2” PVC OR 3/4” PVC
Optional Condensate Drain Connection
Adapter 1/2 inch slip X
1/2 inch mpt (Not Furnished)
90° Street Elbow
1/2 inch PVC
(Not Furnished)
Condensate Drain
Connection In Unit
90° Street Elbow
1/2 inch PVC
(Furnished)
To
Trap
Optional Drain Piping From Trap
Drain Assembly for 1/2 inch Drain Pipe
1/2 inch PVC Pipe
(Not Furnished)
90° Elbow
1/2 inch PVC
(Not Furnished)
To
Drain
Drain Assembly for 3/4 inch Drain Pipe
1 (25 mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit
90° Elbow 1/2 inch PVC
(Not Furnished)
1/2 inch PVC Pipe
(Not Furnished)
Adapter 1/2 inch slip X
1/2 inch mpt (Not Furnished)
Vent
5 Feet
Maximum
1/2 inch PVC Pipe
(Not Furnished)
Coupling 1/2 inch slip X slip
(Not Furnished)
Drain Trap
Assembly
(Furnished)
Condensate Drain
Connection In Unit
90° Elbow
3/4 inch PVC
(Not Furnished)
To
Drain
Drain Trap Assembly
(Furnished)
7
(178)
90° Elbow
3/4 inch PVC
(Not Furnished)
To
Coupling 3/4 inch slip X slip
Drain
Drain Trap Assembly with 1/2 inch Piping
1 (25 mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit
(Not Furnished)
Vent
1/2 inch
Condensate Drain Connection In Unit
To
Drain
Drain Trap Clean Out
Drain Trap Assembly with 3/4 inch Piping
Drain Trap Assembly with 3/4 inch Piping
1 (25 mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit
Vent
3/4 inch
Condensate Drain
Connection In Unit
To
Drain
FIGURE 47
Page 36
Page 37
III-START‐UP A-Preliminary 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 the nameplate. If not, consult the power company and have voltage condition corrected before starting unit.
3 - Inspect condition of condensate traps and drain as
sembly. Disassemble and clean seasonally.
B-Heating Start‐Up
BEFORE LIGHTING the unit, smell all around the furnace
area for gas. Be sure to smell next to the floor because some gas is heavier than air and will settle on the floor.
The gas valve on the ML193DF is equipped with a gas con trol switch. Use only your hand to move the switch. Never use tools. If the the switch will not move by hand, replace the valve. Do not try to repair it. Force or attempted repair may result in a fire or explosion.
Placing the furnace into operation:
ML193DF units are equipped with a SureLight ignition sys tem. Do not
attempt to manually light burners on this fur nace. Each time the thermostat calls for heat, the burners will automatically light The ignitor does not get hot when there is no call for heat on units with SureLightt ignition system.
Priming Condensate Trap
The condensate trap should be primed with water prior to start-up to ensure proper condensate drainage. Either pour 10 fl. oz. (300 ml) of water into the trap, or follow these steps to prime the trap:
1 - Follow the lighting instructions to place the unit into op
eration.
2 - Set the thermostat to initiate a heating demand.
3 - Allow the burners to fire for approximately 3 minutes. 4 - Adjust the thermostat to deactivate the heating de
mand.
5 - Wait for the combustion air inducer to stop. Set the
thermostat to initiate a heating demand and again al low the burners to fire for approximately 3 minutes.
6 - Adjust the thermostat to deactivate the heating de
mand and again wait for the combustion air inducer to stop. At this point, the trap should be primed with suffi cient water to ensure proper condensate drain opera tion.
WARNING
If you do not follow these instructions exactly, a fire or explosion may result causing property damage, personal injury or death.
Gas Valve Operation (Figure 48)
1 - STOP! Read the safety information at the beginning of
this section.
2 - Set the thermostat to the lowest setting. 3 - Turn off all electrical power to the unit. 4 - This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the burners by hand.
5 - Remove the upper access panel. 6 - Move gas valve switch to OFF. See figure 48. 7 - Wait five minutes to clear out any gas. If you then smell
gas, STOP! Immediately call your gas supplier from a neighbor's phone. Follow the gas supplier's instruc tions. If you do not smell gas go to next step.
8 - Move gas valve switch to ON. See figure 48.
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
(under
barbed
fitting)
INLET
PRESSURE
PORT
GAS VALVE SHOWN IN ON POSITION
MANIFOLD PRESSURE
OUTLET
FIGURE 48
9 - Replace the upper access panel.
10- Turn on all electrical power to to the unit.
11- Set the thermostat to desired setting.
NOTE - When unit is initially started, steps 1 through 11 may need to be repeated to purge air from gas line.
12- If the appliance will not operate, follow the instructions
“Turning Off Gas to Unit” and call your service techni cian or gas supplier.
Turning Off Gas to Unit
1 - Set the thermostat to the lowest setting.
2 - Turn off all electrical power to the unit if service is to be
performed.
3 - Remove the upper access panel. 4 - Move gas valve switch to OFF.
5 - Replace the upper access panel.
Failure To Operate
If the unit fails to operate, check the following: 1 - Is the thermostat calling for heat? 2 - Are access panels securely in place? 3 - Is the main disconnect switch closed? 4 - Is there a blown fuse or tripped breaker? 5 - Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off. 6 - Is gas turned on at the meter? 7 - Is the manual main shut‐off valve open? 8 - Is the internal manual shut‐off valve open? 9 - Is the unit ignition system in lockout? If the unit locks
out again, inspect the unit for blockages.
Page 37
Page 38
IV-HEATING SYSTEM SERVICE CHECKS
A-C.S.A. Certification
All units are C.S.A. design certified without modifications. Refer to the ML193DF Operation and Installation Instruc tion Manual Information.
B-Gas Piping
available through Lennox under part number 31B2001. See Corp. 8411-L10, for further details.
WARNING
Do not use matches, candles, flame or any other source of ignition to check for gas leaks.
CAUTION
If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside the furnace cabinet. The flexible connector can then be added between the black iron pipe and the gas supply line.
Gas supply piping should not allow more than 0.5”W.C. drop in pressure between gas meter and unit. Supply gas pipe must not be smaller than unit gas connection.
Compounds used on gas piping threaded joints should be resistant to action of liquefied petroleum gases.
C-Testing Gas Piping
IMPORTANT
In case emergency shutdown is required, turn off the main shut‐off valve and disconnect the main power to unit. These controls should be properly labeled by the installer.
When pressure testing gas lines, the gas valve must be dis connected and isolated. Gas valves can be damaged if subjected to more than 0.5psig (14” W.C.). See figure 49.
MANUAL MAIN SHUT-OFF
VALVE WILL NOT HOLD
NORMAL TEST PRESSURE
1/8” N.P.T. PLUGGED TAP
CAP
FIGURE 49
When checking piping connections for gas leaks, use pre ferred means. Kitchen detergents can cause harmful cor rosion on various metals used in gas piping. Use of a spe cialty Gas Leak Detector is strongly recommended. It is
FURNACE
ISOLATE
GAS VALVE
D-Testing Gas Supply Pressure
When testing supply gas pressure, use the 1/8” N.P.T. plugged tap or pressure post located on the gas valve to facilitate test gauge connection. See figure 48. Check gas line pressure with unit firing at maximum rate. Low pres sure may result in erratic operation or underfire. High pres sure can result in permanent damage to gas valve or over fire.
On multiple unit installations, each unit should be checked separately, with and without units operating. Supply pres sure must fall within range listed in table 19.
E-Check Manifold Pressure
After line pressure has been checked and adjusted, check manifold pressure. Move pressure gauge to outlet pres sure tap located on unit gas valve (GV1). Checks of manifold pressure are made as verification of proper regulator adjustment.
IMPORTANT
For safety, connect a shut‐off valve between the manometer and the gas tap to permit shut off of gas pressure to the manometer.
1 - Remove the threaded plug from the outlet side of the
gas valve and install a field-provided barbed fitting. Connect to a manometer to measure manifold pres sure.
2 - Start unit and allow 5 minutes for unit to reach steady
state.
3 - While waiting for the unit to stabilize, observe the
flame. Flame should be stable and should not lift from burner. Natural gas should burn blue.
4 - After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in table
19.
NOTE - Shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to remove barbed fitting and replace threaded plug.
Page 38
Page 39
F- Proper Gas Flow (Approximate)
Gas Flow (Approximate)
TABLE 18
GAS METER CLOCKING CHART
Seconds for One Revolution
ML193
Unit
-045 80 160 200 400
-070 55 110 136 272
-090 41 82 102 204
-110 33 66 82 164
Natural-1000 btu/cu ft LP-2500 btu/cu ft
NOTE - To obtain accurate reading, shut off all other gas appliances connected to meter.
Furnace should operate at least 5 minutes before checking gas flow. Determine time in seconds for two revolutions of gas through the meter. (Two revolutions assures a more accurate time). Divide by two and compare to time in table
18. If manifold pressure matches table 19 and rate is incor rect, check gas orifices for proper size and restriction. Re move temporary gas meter if installed.
Manifold and Supply Pressure (Outlet) inches w.c.
At All Altitudes For -1 Through -6 Units
Fuel
Nat. Gas All sizes 3.5 4.5 13.0
L.P. Gas All sizes 10.0 11.0 13.0
Natural LP
1 cu ft
Dial
2 cu ft
Dial
TABLE 19
Model
Input Sizes
Manifold
Pressure in.wg.
1 cu ft
Dial
2 cu ft
DIAL
Supply
Pressure in.wg.
Min. Max.
G- Proper Combustion
Furnace should operate at least 15 minutes with correct manifold pressure and gas flow rate before checking com bustions. Take sample beyond the flue outlet and compare to table 20.
TABLE 20
ML193
Unit
CO2%
For Nat
CO2%
For L.P.
-045
-070
-090
7.2 - 7.9 8.6 - 9.3
-110
The carbon monoxide reading should not exceed 50 ppm.
H- High Altitude
NOTE - In Canada, certification for installations at eleva tions over 4500 feet (1372 m) is the jurisdiction of local au thorities.
ML193DF-1 through -6 units require no manifold pressure adjustments for operation at altitudes up to 10,000 feet (3048 m) above sea level. However, -7 units and later in stalled at altitude of 4501 - 10,000 feet (1373 to 3048m) re quire a pressure switch change which can be ordered sep arately and manifold de-rate. See table 19 or table 21 for manifold pressures at varying altitudes. Table 22 lists con version kit and pressure switch requirements at varying al titudes. The combustion air pressure switch is factory-set and re quires no adjustment.
TABLE 21
Manifold and Supply Line Pressure 0-10,000ft. For -7 Units and Later
Manifold Pressure in. wg.
ML193
Unit
All Sizes
NOTE - A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion procedure.
Gas
0-4500 ft. 4501-5500 ft. 5501-6500 ft.
Natural 3.5 3.3 3.2 3.1 3.5 4.5 13.0
LP/propane 10.0 9.4 9.1 8.9 10.0 11.0 13.0
6501 -
7500ft.
7501 - 10000ft.
Supply Line
0 - 10000 ft.
TABLE 22
Conversion Kit and Pressure Switch Requirements at Varying Altitudes
Natural to
ML193
Unit
-045
-070
-090
-110
* Conversion requires installation of a gas valve manifold spring which is provided with the gas conversion kit. Pressure switch is factory set. No adjustment necessary. All models use the factory-installed pressure switch from 0-4500 feet (0-1370 m).
LP/Propane
0 - 7500 ft
(0 - 2286m)
*69W73 73W37 *73W81 93W87 93W88
High Altitude
Natural Burner Ori
fice Kit
7501 - 10,000 ft (2286 - 3038m)
LP/Propane to
Natural
0 - 7500 ft
(0 - 2286m)
High Altitude Pressure Switch
4501 - 7500 ft
(1373 - 2286m)
7501 -10,000 ft
(2286 - 3048m)
Pressure
in. w.g.
Page 39
Page 40
I-Flame Signal
A transducer (Part #78H5401 available from Lennox Re pair Parts) is required to measure flame signal if meter used will not read a low micro amp signal. Seefigure50. The transducer converts microamps to volts on a 1:1 con version. Flame signal is shown in table 23. A digital readout meter must be used. The transducer plugs into most me ters.
TABLE 23
Normal Flame Signal
Low Flame Signal
Drop Out Signal = 0.50 Microamps
To Measure Flame Signal:
1 - Set the volt meter to the DC voltage scale. Insert trans
ducer into the VDC and common inputs. Observe cor rect polarities. Failure to do so results in negative (-)
values. 2 - Turn off supply voltage to control. 3 - Disconnect ignition control flame sensor wire from the
flame sensor. 4 - Connect (-) lead of the transducer to flame sensor. 5 - Connect (+) lead of transducer to the ignition control
sensor wire. 6 - Turn supply voltage on and close thermostat contacts
to cycle system. 7 - When main burners are in operation for two minutes,
take reading. Remember 1 DC volt = 1 DC microamp.
NOTE-MUST USE DIGITAL METER
(+) TO
IGNITION
CONTROL
SENSOR
WIRE
FIGURE 50
1.50 Microamps
1.40 Microamps
SET DIAL TO
MEASURE VDC
(+)
(-)
(-) TO
FLAME
SENSOR
TRANSDUCER PART #78H5401
RED COLLAR
INDICATES
POSITIVE
LEAD
V-TYPICAL OPERATING CHARACTERISTICS
A-Blower Operation and Adjustment
1 - Blower operation is dependent on thermostat control
system.
2 - Generally, blower operation is set at thermostat sub
base fan switch. With fan switch in ON position, blower operates continuously. With fan switch in AUTO posi tion, blower cycles with demand or runs continuously while heating or cooling circuit cycles.
3 - Depending on the type of indoor thermostat, blower
and entire unit will be off when the system switch is in OFF position.
B-Temperature Rise
Temperature rise depends on unit input, blower speed, blower horsepower and static pressure as marked on the unit rating plate. The blower speed must be set for unit op eration within the range of “TEMP. RISE °F” listed on the 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 not pick up ra diant heat from the heat exchanger.
2 - Set thermostat for heat call. Unit must operate on sec
ond-stage heat.
3 - After plenum thermometers have reached their high
est and steadiest readings, subtract the two readings. The difference should be in the range listed on the unit rating plate. If the temperature is too low, decrease blower speed. If temperature is too high, first check the firing rate. Provided the firing rate is acceptable, in crease blower speed to reduce temperature.
C-External Static Pressure
1 - Tap locations shown in figure 51. 2 - Punch a 1/4” diameter hole
in supply and return air ple nums. Insert manometer hose flush with inside edge of hole or insulation. Seal around the hose with perma gum. Connect the zero end of the manometer to the dis charge (supply) side of the system. On ducted sys tems, connect the other end of manometer to the return duct as above.
3 - With only the blower motor running and the evaporator
coil dry, observe the manometer reading. Adjust blow er motor speed to deliver the air desired according to the job requirements.
4 - External static pressure drop must not be more than
0.8” W.C. in the heating mode and must not exceed
1.0” W.C in the cooling mode.
5 - Seal the hole when the check is complete. To change existing heat tap, turn off power then switch out speed tap with tap connected to ”PARK” . See unit diagram for blower motor tap colors for each speed.
STATIC PRESSURE TEST
filter
coil
FIGURE 50
Page 40
Page 41
VI-MAINTENANCE
Furnace
Cabinet Width
TABLE 24
Filter Size
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result in dangerous operation, serious injury, death or property damage. Improper servicing could result in dangerous opera tion, serious injury, death, or property damage. Before servicing, disconnect all electrical power to furnace. When servicing controls, label all wires prior to dis connecting. Take care to reconnect wires correctly. Verify proper operation after servicing.
At the beginning of each heating season, system should be checked as follows by a qualified service technician:
Blower
Check the blower wheel for debris and clean if necessary. The blower motors are prelubricated for extended bearing life. No further lubrication is needed.
17-1/2”
21”
Exhaust and air intake pipes
Check the exhaust and air intake pipes and all connections for tightness and to make sure there is no blockage.
NOTE - After any heavy snow, ice or frozen fog event the furnace vent pipes may become restricted. Always check the vent system and remove any snow or ice that may be obstructing the plastic intake or exhaust pipes.
Electrical
1 - Check all wiring for loose connections. 2 - Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC +
3 - Check amp-draw on the blower motor with blower ac
cess panel in place. Motor Nameplate__________Actual__________
Winterizing and Condensate Trap Care
1 - Turn off power to the furnace.
2 - Have a shallow pan ready to empty condensate water.
3 - Remove the clean out cap from the condensate trap
and empty water. Inspect the trap then reinstall the clean out cap.
16 x 25 x 1 (1)
10%
WARNING
The blower access panel must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into living space resulting in personal inju ry or death.
Filters
All air filters are installed external to the unit. Filters should be inspected monthly. Clean or replace the filters when necessary to ensure proper furnace operation. Table 24 lists recommended filter sizes.
IMPORTANT
If a highefficiency filter is being installed as part of this system to ensure better indoor air quality, the fil ter must be properly sized. Highefficiency filters have a higher static pressure drop than standardef ficiency glass/foam filters. If the pressure drop is too great, system capacity and performance may be re duced. 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 Lennox Product Specifications bulletin. Additional informa tion is provided in Service and Application Note ACC002 (August 2000).
Condensate Hose Screen (Figure 52)
Check the condensate hose screen for blockage and clean
if necessary. 1 - Turn off power to the unit. 2 - Remove hose from cold end header box. Twist and pull
screen to remove. 3 - Inspect screen and rinse with tap water if needed. 4 - Reinstall screen and turn on power to unit.
Condensate Hose Screen
Hose
FIGURE 52
Cleaning Heat Exchanger
If cleaning the heat exchanger becomes necessary, follow the below procedures and refer to figure 1 when disassem bling unit. Use papers or protective covering in front of fur nace while removing heat exchanger assembly.
1 - Turn off electrical and gas supplies to the furnace. 2 - Remove the furnace access panels. 3 - Disconnect the 2 wires from the gas valve. 4 - Remove gas supply line connected to gas valve. Re
move gas valve/manifold assembly.
5 - Remove sensor wire from sensor. Disconnect 2‐pin
plug from the ignitor.
Page 41
Page 42
6 - Disconnect wires from flame roll-out switches. 7 - Loosen clamps at vent elbow. Disconnect condensate
drain tubing from flue collar. and remove the vent el bow.
8 - Remove four burner box screws at the vestibule panel
and remove burner box. Set burner box assembly aside.
NOTE - If necessary, clean burners at this time. Follow procedures outlined in Burner Cleaning section.
9 - Mark and disconnect all combustion air pressure tub
ing from cold end header collector box.
10 - Mark and remove wires from pressure switches. Re
move pressure switches. Keep tubing attached to pressure switches.
11 - Disconnect the plug from the combustion air inducer.
Remove two screws which secure combustion air in ducer to collector box. Remove combustion air induc er assembly. Remove ground wire from vest panel.
12 - Remove electrical junction box from the side of the fur
nace.
13 - Mark and disconnect any remaining wiring to heating
compartment components. Disengage strain relief bushing and pull wiring and bushing through the hole
in the blower deck. 14 - Remove the primary limit from the vestibule panel. 15 - Remove two screws from the front cabinet flange at
the blower deck. Spread cabinet sides slightly to allow
clearance for removal of heat exchanger. 16 - Remove screws along vestibule sides and bottom
which secure vestibule panel and heat exchanger as
sembly to cabinet. Remove two screws from blower
rail which secure bottom heat exchanger flange. Re
move heat exchanger from furnace cabinet. 17 - Back wash heat exchanger with soapy water solution
or steam. If steam is used it must be below 275°F
(135°C) .
18 - Thoroughly rinse and drain the heat exchanger. Soap
solutions can be corrosive. Take care to rinse entire
assembly. 19 - Reinstall heat exchanger into cabinet making sure that
the clamshells of the heat exchanger assembly are
resting on the support located at the rear of the cabi
net. Remove the indoor blower to view this area
through the blower opening. 20 - Re‐secure the supporting screws along the vestibule
sides and bottom to the cabinet. Reinstall blower and
mounting screws. 21 - Reinstall cabinet screws on front flange at blower
deck. 22 - Reinstall the primary limit on the vestibule panel. 23 - Route heating component wiring through hole in blow
er deck and reinsert strain relief bushing. 24 - Reinstall electrical junction box. 25 - Reinstall the combustion air inducer. Reconnect the
combustion air inducer to the wire harness.
26 - Reinstall pressure switches and reconnect pressure
switch wiring.
27 - Carefully connect combustion air pressure switch hos
ing from pressure switches to proper stubs on cold end
header collector box. 28 - Reinstall condensate trap. 29 - Reconnect exhaust piping and exhaust drain tubing. 30 - Reinstall burner box assembly in vestibule area. 31 - Reconnect flame roll-out switch wires. 32 - Reconnect sensor wire and reconnect 2-pin plug from
ignitor. 33 - Secure burner box assembly to vestibule panel using
four existing screws. Make sure burners line up in
center of burner ports.
34 - Reinstall gas valve manifold assembly. Reconnect
gas supply line to gas valve. 35 - Reconnect 2 wires to gas valve. 36 - Replace the blower compartment access panel. 37 - Refer to instruction on verifying gas and electrical con
nections when re-establishing supplies. 38 - Follow lighting instructions to light and operate fur
nace for 5 minutes to ensure that heat exchanger is
clean and dry and that furnace is operating properly. 39 - Replace heating compartment access panel.
Cleaning the Burner Assembly
1 - Turn off electrical and gas power supplies to furnace.
Remove upper and lower furnace access panels. 2 - Disconnect the 2-pin plug from the gas valve. 3 - Remove the burner box cover. 4 - Disconnect the gas supply line from the gas valve. Re
move gas valve/manifold assembly. 5 - Mark and disconnect sensor wire from the sensor. Dis
connect 2‐pin plug from the ignitor at the burner box. 6 - Remove four screws which secure burner box assem
bly to vest panel. Remove burner box from the unit. 7 - Use the soft brush attachment on a vacuum cleaner to
gently clean the face of the burners. Visually inspect
the inside of the burners and crossovers for any block
age caused by foreign matter. Remove any blockage. 8 - Reconnect the sensor wire and reconnect the 2-pin
plug to the ignitor wiring harness. 9 - Reinstall the burner box assembly using the existing
four screws. Make sure that the burners line up in the
center of the burner ports. 10 - Reinstall the gas valve manifold assembly. Reconnect
the gas supply line to the gas valve. Reinstall the burn
er box cover. 11 - Reconnect 2-pin plug to gas valve. 12 - Replace the blower compartment access panel. 13 - Refer to instruction on verifying gas and electrical con
nections when re-establishing supplies. 14 - Follow lighting instructions to light and operate fur
nace for 5 minutes to ensure that heat exchanger is
clean and dry and that furnace is operating properly. 15 - Replace heating compartment access panel.
Page 42
Page 43
VII-WIRING DIAGRAM AND SEQUENCE OF OPERATION
ML193DF With Integrated Control 100973
1 - When there is a call for heat, W1 of the thermostat en
ergizes W of the furnace control with 24VAC.
2 - S10 primary limit switch and S47 rollout switch are
closed. Call for heat can continue.
3 - The integrated contol (A92) energizes combustion air
inducer B6. Combustion air inducer runs until S18 combustion air prove switch closes (switch must close within 2-1/2 minutes or control goes into 5 minute Watchguard Pressure Switch delay). Once S18 closes, a 15-second pre-purge follows.
4 - The integrated control (A92) energizes ignitor. A
20-second warm-up period begins.
5 - Gas valve opens for a 4-second trial for ignition
6 - Flame is sensed, gas valve remains open for the heat
call.
7 - After 30-second delay, the integrated control (A92)
energizes indoor blower B3.
8 - When heat demand is satisfied, W1 of the indoor ther
mostat de-energizes W of the integrated control which de-energizes the gas valve. Combustion air inducer B6 continues a 5-second post-purge period, and in door blower B3 completes a selected OFF time delay.
Page 43
Page 44
Sequence of Operation Flow Chart - Integrated Control 100973
HEATING SEQUENCE OF OPERATION
NORMAL HEATING MODE
POWER ON
CONTROL SELF-CHECK OKAY?
YES
IS POLARITY CORRECT?
YES
IS THERE A PROPER GROUND?
YES
IS VOLTAGE
ABOVE 90 VOLTS?
YES
ROLLOUT SWITCH CLOSED?
YES
NO
NO
NO
ABNORMAL HEATING MODE
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
(RESET CONTROL BY TURNING MAIN POWER OFF.)
NO
NO
HEATING UNTIL VOLTAGE RISES ABOVE 95 VOLTS.
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES
AND POWER IS RESET OR T'STAT IS INTERRUPTED
INDOOR BLOWER DELAY OFF.
LED #1 ON LED #2 ON
POLARITY REVERSED.
LED #1 -- FAST FLASH
LED #2 -- SLOW FLASH
IMPROPER GROUND. LED #1 -- ALTERNATING FAST FLASH LED #2 -- ALTERNATING FAST FLASH
LEDs SIGNAL FAST ALTERNATING FLASH.
CONTROL WILL NOT RESPOND TO A CALL FOR
INDOOR BLOWER ON.
LED #1 -- ON. LED #2 -- SLOW FLASH.
FOR MINIMUM OF 1 SECOND.
NO
(Flame sensed without gas valve energized)
BURNER OFF?
YES
NORMAL OPERATION:
LED #1 -- SLOW FLASH LED #2 -- SLOW FLASH
YES
THERMOSTAT CALLS FOR HEAT:
LED #1 -- FAST FLASH LED #2 -- FAST FLASH
YES
PRIMARY LIMIT SWITCH. CLOSED?
YES
IS COMBUSTION AIR
PRESSURE SWITCH OPEN?
YES
IS COMBUSTION AIR INDUCER
ENERGIZED?
YES
HAS COMBUSTION AIR PRESSURE
SWITCH CLOSED IN 2.5 MINUTES?
YES
NO
NO
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON HEATING SPEED.
NO
NO
PRESSURE SWITCH IS IN WATCHGUARD MODE.
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 -- OFF. LED #2 -- SLOW FLASH.
IS 5‐MINUTE RESET PERIOD COMPLETE?
LED #1 -- SLOW FLASH
LED #2 -- OFF
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER ON
LED #1 SLOW FLASH RATE
LED #2 -- ON
GAS VALVE OFF.
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 OFF
LED #2 SLOW FLASH
(Sequence holds until pressure switch
opens or thermostat resets control.)
YES
CONTINUED NEXT
PAGE
Page 44
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HEATING SEQUENCE CONTINUED
NORMAL HEATING MODE ABNORMAL HEATING MODE
15‐SECOND COMBUSTION AIR INDUCER PREPURGE
INITIATED BY CLOSED PRESSURE SWITCH.
YES
IGNITOR WARM‐UP -- 20 SECONDS.
YES
4‐SECOND TRIAL FOR IGNITION.
GAS VALVE OPENS. IGNITOR ENERGIZED FOR
FIRST 3 SECONDS OF THE TRIAL.
YES
FLAME STABILIZATION PERIOD.
4 SECONDS
FLAME RECTIFICATION CURRENT
CHECK. CAN FLAME BE PROVEN WITHIN
4 SECONDS AFTER GAS VALVE OPENS?
(0.5 microamps)
YES
FLAME PRESENT?
YES
FLAME SIGNAL 1.5 MICROAMPS OR GREATER?
YES
INDOOR BLOWER ON
AFTER 30-SECOND DELAY
YES
PRIMARY AND SECONDARY LIMIT
SWITCHES CLOSED?
YES
NO
IS VOLTAGE ABOVE 90 VOLTS?
YES
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
NO
HAS CONTROL FAILED TO SENSE FLAME FOR
FIVE CONSECUTIVE TRIES DURING A SINGLE
WATCHGUARD MODE. GAS VALVE OFF.
LEDs SIGNAL WATCHGUARD FAILURE CODE.
IS 60‐MINUTE RESET PERIOD COMPLETE?
NO
NO
(Does not affect operation of control)
LED #1 -- SLOW FLASH
COMBUSTION AIR INDUCER DE-ENERGIZED.
INDOOR BLOWER ON UNTIL SWITCH CLOSES.
NO
LED #1 -- SLOW FLASH. LED #2 -- ON.
HAS PRIMARY / SECONDARY
INDOOR BLOWER OFF.
HEAT DEMAND?
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY
HAS CONTROL RESET IGNITION
SEQUENCE FOUR TIMES?
LOW FLAME SIGNAL
LED #2 -- FAST FLASH
GAS VALVE DE-ENERGIZED.
IS LIMIT SWITCH CLOSED?
YES
LIMIT RESET TIME
EXCEEDED 3 MINUTES?
LEDS SIGNAL
NO
LIMIT SWITCH WATCHGUARD
MODE. GAS VALVE, COMB. AIR
INDUCER AND INDOOR BLOW
ER OFF. LEDs SIGNAL LIMIT
SWITCH OPEN UNTIL MAIN
YES
ALTERNATING
FAST FLASH UNTIL
VOLTAGE IS ABOVE
95 VOLTS, THEN
RESTARTS HEATING
SEQUENCE.
NO
YES
YES
NO
YES
POWER IS
INTERRUPTED OR
T'STAT IS CYCLED
OFF/ON FOR 1 SEC.
MINIMUM. 60-MIN UTE WATCHGUARD PERIOD STARTS AT
TIME LIMIT CLOSES.
IS 60-MIN. PERIOD
COMPLETE?
NO
ROLLOUT SWITCH CLOSED?
YES
COMBUSTION AIR PRESSURE
SWITCH CLOSED?
YES
THERMOSTAT DEMAND SATISFIED.
YES
LED #1 & #2 SIMULTANEOUS SLOW FLASHES.
YES
COMB. AIR INDUCER CONTINUES 5‐SECOND
POST PURGE AFTER T'STAT DEMAND IS SATISFIED.
INDOOR AIR BLOWER COMPLETES SELECTED “OFF”
DELAY BEFORE SHUTTING OFF.
NO
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET
NO
THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.
HAS PRESSURE SWITCH OPENED 5
TIMES IN THE SAME HEAT DEMAND?
GAS VALVE DE-ENERGIZED.
COMBUSTION AIR INDUCER ON.
INDOOR BLOWER OFF WITH DELAY
LED #1 -- OFF. LED #2 -- SLOW FLASH.
HAS CAB SWITCH CLOSED IN 2.5 MINUTES?
5‐MINUTE PRESSURE SWITCH
WATCHGUARD MODE.
GAS VALVE POWER OFF.
COMBUSTION AIR INDUCER POWER ON.
INDOOR BLOWER ON
LED #1 -- ON. LED #2 -- SLOW FLASH.
AND MAIN POWER IS INTERRUPTED OR
NO
NO
Page 45
YES
WATCHGUARD
1 HR
PRESSURE
SWITCH
MODE
Page 46
COOLING SEQUENCE OF OPERATION
NORMAL COOLING MODE ABNORMAL COOLING MODE
POWER ON
IGNITION CONTROL MAIN POWER ON.
CONTROL SELF DIAGNOSTIC CHECK.
IS CONTROL OPERATING NORMALLY?
YES
IS THERE A PROPER GROUND?
YES
IS POLARITY CORRECT?
YES
NO
IS VOLTAGE
ABOVE 90 VOLTS?
YES
ROLLOUT SWITCH MONITORED CONTINUOUSLY.
IS ROLLOUT SWITCH CLOSED?
YES
NO
NO
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT CONTROL FAILURE AT LED.
INTERRUPT MAIN POWER TO RESET CONTROL.
NO
NO
SIGNAL IMPROPER GROUND AT LED.
CONTROL WILL CONTINUE TO CALL FOR COOLING
IN THIS CONDITION.
SIGNAL POLARITY REVERSED AT LED. CONTROL
WILL CONTINUE TO CALL FOR COOLING IN THIS
CONDITION.
LED SIGNALS LOW VOLTAGE. CONTROL WILL
CONTINUE TO CALL FOR COOLING
IN THIS CONDITION.
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON.
SIGNAL ROLL‐OUT SWITCH OPEN AT LED.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES
AND MAIN POWER IS INTERRUPTED OR THERMOSTAT
IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.
LED: SLOW FLASH RATE REMAINS UNCHANGED
THROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FAN
ENERGIZED WITH 2‐SECOND DELAY
(COOLING SPEED). EAC TERM. ENERGIZED.
THERMOSTAT OPENS.
COMPRESSOR OFF.
SYSTEM FAN AND EAC TERM. OFF
WITH 45‐SECOND DELAY.
Page 46
Page 47
CONTINUOUS HEAT SPEED FAN SEQUENCE OF OPERATION
LED: SLOW FLASH RATE REMAINS
UNCHANGED THROUGHOUT SEQUENCE.
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES SYSTEM FAN AT HEAT
SPEED. EAC TERMINAL IS ENERGIZED.
THERMOSTAT CALLS FOR HEAT (W).
NO
THERMOSTAT CALLS FOR COOLING.
YES
SYSTEM FAN SWITCHED TO COOL SPEED.
EAC TERM. REMAINS ON.
THERMOSTAT OPENS.
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES SYSTEM FAN AT HEAT
SPEED. EAC TERM. ENERGIZED.
NO
HUM TERM. ENERGIZES
WITH COMB. AIR INDUCER.
YES
SYSTEM FAN REMAINS ON
HEATING SPEED.
THERMOSTAT OPENS.
HUM TERM. DE-ENERGIZES
WITH COMB. AIR INDUCER
SYSTEM FAN REMAINS ON
HEATING SPEED.
Page 47
Page 48
ML193DF With Integrated Control 103085
1 - When there is a call for heat, W1 of the thermostat en
ergizes W of the furnace control with 24VAC.
2 - S10 primary limit switch and S47 rollout switch are
closed. Call for heat can continue.
3 - The integrated control (A92) energizes combustion air
inducer B6. Combustion air inducer runs until S18 combustion air prove switch closes (switch must close within 2-1/2 minutes or control goes into 5 minute Watchguard Pressure Switch delay). Once S18 closes, a 15-second pre-purge follows.
4 - The integrated control (A92) energizes ignitor. A
20-second warm-up period begins.
5 - Gas valve opens for a 4-second trial for ignition
6 - Flame is sensed, gas valve remains open for the heat
call.
7 - After 30-second delay, the integrated control (A92)
energizes indoor blower B3.
8 - When heat demand is satisfied, W1 of the indoor ther
mostat de-energizes W of the integrated control which de-energizes the gas valve. Combustion air inducer B6 continues a 5-second post-purge period, and in door blower B3 completes a selected OFF time delay.
Page 48
Page 49
Sequence of Operation Flow Chart - Integrated Control 103085
HEATING SEQUENCE OF OPERATION
NORMAL HEATING MODE
POWER ON
CONTROL SELF-CHECK OKAY?
YES
IS POLARITY CORRECT?
YES
IS THERE A PROPER GROUND?
YES
IS VOLTAGE
ABOVE 90 VOLTS?
YES
ROLLOUT SWITCH CLOSED?
YES
NO
NO
ABNORMAL HEATING MODE
NO
NO
NO
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER DELAY OFF.
LED: OFF
POLARITY REVERSED.
LED: 9 FLASHES
IMPROPER GROUND.
LED: OFF
CONTROL WILL NOT RESPOND TO CALL FOR HEAT
UNTIL PROPER GROUND.
LED: ON STEADY
IGNITOR WILL GLOW DIMLY BUT WILL NOT LIGHT
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON.
LED: 5 FLASHES
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES
AND POWER IS RESET OR T'STAT IS INTERRUPTED
FOR MINIMUM OF 1 SECOND.
NO
BURNER OFF?
(Contiuous Flame Check)
YES
NORMAL OPERATION:
LED: STEADY ON
YES
THERMOSTAT CALLS FOR
HEAT:
LED: STEADY ON
YES
PRIMARY AND SECONDARY LIMIT SWITCH.
CLOSED?
YES
IS COMBUSTION AIR
PRESSURE SWITCH OPEN?
YES
IS COMBUSTION AIR INDUCER
ENERGIZED?
YES
HAS COMBUSTION AIR PRESSURE
SWITCH CLOSED IN 2.5 MINUTES?
YES
CONTINUED NEXT
PAGE
NO
NO
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON HEATING SPEED.
COMBUSTION AIR INDUCER OFF.
NO
NO
PRESSURE SWITCH IS IN WATCHGUARD MODE.
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY.
IS 5‐MINUTE RESET PERIOD COMPLETE?
LED: 1 FLASH
INDOOR BLOWER ON
LED: 4 FLASHES
GAS VALVE OFF.
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH
DELAY.
LED: 2 FLASHES
(Sequence holds until pressure switch
opens or thermostat resets control.)
LED: 3 FLASHES
YES
Page 49
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HEATING SEQUENCE CONTINUED
NORMAL HEATING MODE ABNORMAL HEATING MODE
15‐SECOND COMBUSTION AIR INDUCER PREPURGE
INITIATED BY CLOSED PRESSURE SWITCH.
YES
IGNITOR WARM‐UP -- 20 SECONDS.
YES
4‐SECOND TRIAL FOR IGNITION.
GAS VALVE OPENS.
YES
FLAME STABILIZATION PERIOD.
4 SECONDS
FLAME RECTIFICATION CURRENT
CHECK. CAN FLAME BE PROVEN WITHIN
4 SECONDS AFTER GAS VALVE OPENS?
YES
FLAME PRESENT?
YES
NO
IS VOLTAGE ABOVE 90 VOLTS?
YES
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
NO
HAS CONTROL FAILED TO SENSE FLAME FOR
FIVE CONSECUTIVE TRIES DURING A SINGLE
WATCHGUARD MODE. GAS VALVE OFF.
LED: 7 FLASHES WATCHGUARD FAILURE CODE.
IS 60‐MINUTE RESET PERIOD COMPLETE?
NO
INDOOR BLOWER OFF.
HEAT DEMAND?
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY
HAS CONTROL RESET IGNITION
SEQUENCE FOUR TIMES?
NO
LED: ON STEADY
UNTIL VOLTAGE IS
ABOVE 95 VOLTS,
THEN RESTARTS
HEATING
SEQUENCE.
NO
YES
YES
NO
FLAME SIGNAL 1.5 MICROAMPS OR GREATER?
YES
INDOOR BLOWER ON
AFTER 30-SECOND DELAY
YES
PRIMARY AND SECONDARY LIMIT
SWITCHES CLOSED?
YES
ROLLOUT SWITCH CLOSED?
YES
COMBUSTION AIR PRESSURE
SWITCH CLOSED?
YES
THERMOSTAT DEMAND SATISFIED.
YES
LED: ON STEADY
YES
COMB. AIR INDUCER CONTINUES 15‐SECOND
POST PURGE AFTER T'STAT DEMAND IS SATISFIED.
INDOOR AIR BLOWER COMPLETES SELECTED “OFF”
DELAY BEFORE SHUTTING OFF.
NO
COMBUSTION AIR INDUCER DE-ENERGIZED.
INDOOR BLOWER ON UNTIL SWITCH CLOSES.
NO
NO
NO
NO
LOW FLAME SIGNAL
(Does not affect operation of control)
LED: ON STEADY
GAS VALVE DE-ENERGIZED.
LED: 4 FLASHES
IS LIMIT SWITCH CLOSED?
NO
5 MINUTE WATCHGUARD MODE.
HAS LIMIT SWITCHED CLOSED
AFTER 5 MINUTES?
GAS VALVE POWER OFF.
COMBUSTION AIR INDUCER POWER ON AFTER 15
SECOND DELAY. INDOOR BLOWER ON
LED: 5 FLASHES
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET
AND MAIN POWER IS INTERRUPTED OR
THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.
HAS PRESSURE SWITCH OPENED 5
TIMES IN THE SAME HEAT DEMAND?
NO
GAS VALVE DE-ENERGIZED.
COMBUSTION AIR INDUCER ON.
INDOOR BLOWER OFF WITH DELAY
LED: 6 FLASHES 5 MINUTE PRESSURE
SWITCH WATCHGUARD MODE.
YES
YES
YES
WATCHGUARD
1 HR
PRESSURE
SWITCH
MODE
Page 50
Page 51
COOLING SEQUENCE OF OPERATION
NORMAL COOLING MODE ABNORMAL COOLING MODE
POWER ON
IGNITION CONTROL MAIN POWER ON. LED: ON STEADY
CONTROL SELF DIAGNOSTIC CHECK.
IS CONTROL OPERATING NORMALLY?
YES
IS THERE A PROPER GROUND?
YES
IS POLARITY CORRECT?
YES
NO
IS VOLTAGE
ABOVE 90 VOLTS?
YES
NO
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH NORMAL DELAY.
INTERRUPT MAIN POWER TO RESET CONTROL.
NO
CONTROL WILL CONTINUE TO CALL FOR COOLING
NO
CONTROL WILL CONTINUE TO CALL FOR COOLING
CONTROL WILL CONTINUE TO CALL FOR
COOLING IN THIS CONDITION.
LED: OFF
LED: ON STEADY
IN THIS CONDITION.
LED: 9 FLASHES
IN THIS CONDITION.
LED: ON STEADY.
REMAINS UNCHANGED THROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FAN
ENERGIZED WITH 2‐SECOND DELAY
(COOLING SPEED). EAC TERM. ENERGIZED.
SYSTEM FAN AND EAC TERM. OFF
LED: ON STEADY.
THERMOSTAT OPENS.
COMPRESSOR OFF.
WITH 60‐SECOND DELAY.
CONTINUOUS FAN SEQUENCE OF OPERATION
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES SYSTEM FAN ON CONTINUOUS
BLOWER SPEED. EAC TERMINAL IS ENERGIZED.
THERMOSTAT CALLS FOR HEAT (W).
NO
THERMOSTAT CALLS FOR COOLING.
YES
SYSTEM FAN SWITCHED TO COOL SPEED.
EAC TERM. REMAINS ON.
LED: ON STEADY
NO
HUM TERM. ENERGIZES
WITH COMB. AIR INDUCER.
YES
SYSTEM FAN SWITCHES TO
HEATING SPEED.
THERMOSTAT OPENS.
THERMOSTAT OPENS.
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES SYSTEM FAN ON
CONTINUOUS BLOWER SPEED.
HUM TERM. DE-ENERGIZES WITH COMB. AIR INDUCER
SYSTEM FAN SWITCHES TO
CONTINUOUS BLOWER SPEED
.
Page 51
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