Lennox ML195UH 045XP24B Unit Information

Lennox ML195UH 045XP24B Unit Information

Ml195uh series

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Service Literature
ML195UH series units are high-efficiency gas furnaces
manufactured with Lennox DuralokPlust aluminized steel
clamshell-type heat exchangers, with a stainless steel con­
densing coil. ML195UH units are available in heating input
capacities of 44,000 to 132,000 Btuh (13 to 38.6 kW) and
cooling applications from 2 through 5 tons (7.0 through
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 ML195UH
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.
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

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Corp. 1035-L7
Revised 03-2014
ML195UH SERIES UNITS
2
3
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4
7
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20
45
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46
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48
49
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52
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.
Sharp edges.
Be careful when servicing unit to avoid sharp edges
which may result in personal injury.
Page 1
ML195UH
WARNING
© 2014 Lennox Industries Inc.
Litho U.S.A.

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Summary of Contents for Lennox ML195UH 045XP24B

  • Page 1: Table Of Contents

    Service Literature ML195UH SERIES UNITS ML195UH series units are high-efficiency gas furnaces manufactured with Lennox DuralokPlust aluminized steel clamshell-type heat exchangers, with a stainless steel con­ densing coil. ML195UH units are available in heating input capacities of 44,000 to 132,000 Btuh (13 to 38.6 kW) and cooling applications from 2 through 5 tons (7.0 through...
  • Page 2: Specifications

    SPECIFICATIONS Model No. ML195UH ML195UH ML195UH ML195UH Heating 045XP24B 045XP36B 070XP36B 090XP36C Performance AFUE Input - Btuh 44,000 44,000 66,000 88,000 Output - Btuh 41,000 42,000 64,000 85,000 Temperature rise range - °F 40 - 70 25 - 55 40 - 70 50 - 80 Gas Manifold Pressure (in.
  • Page 3: Optional Accessories

    OPTIONAL ACCESSORIES - MUST BE ORDERED EXTRA “B” Width Models “C” Width Models “D” Width Models CABINET ACCESSORIES Horizontal Suspension Kit - Horizontal only 51W10 51W10 51W10 Return Air Base - Upflow only 50W98 50W99 51W00 CONDENSATE DRAIN KITS Condensate Drain Heat Cable 6 ft.
  • Page 4: Blower Performance Data

    BLOWER DATA ML195UH045XP24B PERFORMANCE (Less Filter) ML195UH090XP36C PERFORMANCE (Less Filter) Air Volume / Watts at Various Blower Speeds Air Volume / Watts at Various Blower Speeds External External Medium- Medium- Static Static High Medium-Low High Medium-Low High High Pressure Pressure in.
  • Page 5 BLOWER DATA ML195UH110XP60C PERFORMANCE (Less Filter) Air Volume / Watts at Different Blower Speeds Bottom Return Air, Side Return Air with Optional Return Air Single Side Return Air − Air volumes in bold require field External Base, Return Air from Both Sides or Return Air from Bottom fabricated transition to accommodate 20 x 25 x 1 in.
  • Page 6 ML195UH PARTS IDENTIFICATION FLEXIBLE NO-HUB EXHAUST COLLAR TOP CAP MANIFOLD BURNER BOX ASSEMBLY ROLLOUT SWITCHES GAS VALVE DuralokPlus HEAT EXCHANGER ASSEMBLY COMBUSTION AIR INDUCER BURNER ACCESS PANEL CABINET BAG ASSEMBLIES COMBUSTION (shipping location) PRIMARY LIMIT AIR PRESSURE SWITCH SIGHT BLOWER COLD END GLASS ASSEMBLY...
  • Page 7: I-Unit Components

    I-UNIT COMPONENTS WARNING ML195UH unit components are shown in figure 1. The combustion air inducer, gas valve and burners can be ac­ Shock hazard. cessed by removing the burner access panel. The blower Disconnect power before servicing. Control is not and control box can be accessed by removing the blower field repairable.
  • Page 8 tial in the prove switch is great enough, the prove switch Fan Control closes and a 15-second pre-purge begins. If the prove The fan on time of 30 seconds is not adjustable. The fan off delay (amount of time that the blower operates after the switch is not proven within 2-1/2 minutes, the integrated heat demand has been satisfied) may be adjusted by control goes into Watchguard-Pressure Switch mode for a...
  • Page 9 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 Power on - Normal operation. SIMULTANEOUS SIMULTANEOUS Also signaled during cooling and continuous fan.
  • Page 10 4. Integrated Ignition Control 103085 (A92) TABLE 5 12-Pin Terminal Designations PIN # FUNCTION WARNING High Limit Output Sensor Shock hazard. 24V Line Disconnect power before servicing. Control is not Not Used field repairable. If control is inoperable, simply re­ place entire control.
  • Page 11 INTEGRATED CONTROL (Automatic Hot Surface Ignition System) TERMINAL DESIGNATIONS Humidifier (120VAC) Input (120VAC) LINE Transformer (120VAC) XFMR Indoor Air Qality Accessory Air Cleaner (120VAC) Blower - Cooling Speed (120VAC) COOL Blower - Heating Speed (120VAC) HEAT Dead terminals to park alternate spd taps PARK Continuous blower CONT...
  • Page 12 Fan Time Control Twinning 2 ML195UH Furnaces Heating Fan On Time Integrated control 103085 is equipped with a provision to ”twin” (interconnect) two(2) adjacent furnaces with a com­ The fan on time of 30 seconds is not adjustable. mon plenum such that they operate as one (1) large unit. Heating Fan Off Time When twinned, the circulating blower speeds are synchro­...
  • Page 13 FIELD WIRING FOR TWINNING THE ML195UH TWIN TWIN SINGLE STAGE THERMOSTAT TWO-STAGE THERMOSTAT Call For Cool Call For Cool TWIN 1 TWIN 1 Call For Fan Call For Fan Call For 1st Call For Heat Stage Heat Call For 2nd StageHeat TWIN TWIN...
  • Page 14 B-Heating Components Burner Detail Top View Combustion air inducer (B6), primary limit control (S10), IGNITOR 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.
  • Page 15 24VAC terminals and gas control switch are located on top NOTE - The ML195UH furnace contains electronic of the valve. All terminals on the gas valve are connected to components that are polarity sensitive. Make sure that wires from the ignition control. 24V applied to the terminals the furnace is wired correctly and is properly grounded.
  • Page 16 Measuring Flame Signal Flame Signal In Microamps Normal Drop Out  1.5  0.4 0.5 - 1.4 Flame Sensor Wire Remove sensor wire from integrated control connect alligator clip(-) to flame sensor lead. Multi−Meter Intergrated Control Set Dial to Ohms Flame Sensor Terminal To Flame...
  • Page 17 IGNITOR CHECKS TABLE 8 Control Ohms Voltage + 10% 39 to 70 103085 Test 1 24 to 47 100973 Check ignitor circuit for correct resistance. Remove 4-pin plug from control. Check ohms reading across terminals 2 and 4. See table 8. 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.
  • Page 18 8. Combustion Air Inducer (B6) Pressure Switch & Cold End Header Box All ML195UH units use a combustion air inducer to move air through the burners and heat exchanger during heating operation. The blower uses a shaded pole 120VAC motor. The motor operates during all heating operation and is con­...
  • Page 19 Measuring Pressure Differential Black Tubing Red Tubing (positive +) (negative -) To Cold End Header Box To Cold End Header Box Field Provided Tubing To Pressure Switch “+” High “-” 1 - Remove thermostat demand and allow unit to cycle 4 - Operate unit and observe manometer reading.
  • Page 20: Placement And Installation

    II-PLACEMENT AND INSTALLATION places, exhaust fans, or clothes dryers are used at the same time as the furnace, much more air is required to en­ sure proper combustion and to prevent a downdraft. Insuf­ Combustion, Dilution & Ventilation Air ficient air causes incomplete combustion which can result If the ML195UH is installed as a Non-Direct Vent Fur­...
  • Page 21 Air from Inside If the confined space that houses the furnace adjoins a EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE space categorized as unconfined, air can be brought in by (Inlet Air from Crawl Space and Outlet Air to Ventilated Attic) providing two permanent openings between the two VENTILATION LOUVERS spaces.
  • Page 22 CAUTION EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE (All Air Through Ventilated Attic) 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 ROOF TERMINATED VENTILATION LOUVERS EXHAUST PIPE...
  • Page 23: Joint Cementing Procedure

    Low temperature solvent cement is recommended during Canadian Applications Only - Pipe, fittings, primer and cooler weather. Metal or plastic strapping may be used for solvent cement used to vent (exhaust) this appliance must vent pipe hangers. Uniformly apply a liberal coat of PVC be certified to ULC S636 and supplied by a single primer for PVC or use a clean dry cloth for ABS to clean in­...
  • Page 24: Venting Practices

    6 - Promptly apply solvent cement to end of pipe and in­ 2. In areas where piping penetrates joists or interior side socket surface of fitting. Cement should be ap­ walls, hole must be large enough to allow clearance on plied lightly but uniformly to inside of socket.
  • Page 25 Vent Piping Guidelines MINIMUM VENT PIPE LENGTHS ML195UH MIN. VENT LENGTH* ® NOTE - Lennox has approved the use of DuraVent manu­ MODEL factured vent pipe and terminations as an option to PVC. 15 ft. or 045, 070, 090, 110 ®...
  • Page 26 TABLE 14 Maximum Allowable Vent Length in Feet NOTE - 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 - 4500 ft 2”...
  • Page 27 TABLE 14 Continued Maximum Allowable Vent Length in Feet Concentric Termination at Elevation 0 - 4500 ft 2” Pipe 2-1/2” Pipe 3” Pipe Number Of 90° Elbows Model Model Model Used Concentric Termination Elevation 4501 - 10,000 ft 2” Pipe 2-1/2”...
  • Page 28 TABLE 15 Maximum Allowable Exhaust Vent Lengths With Furnace Installed in a Closet or Basement Using Ventilated Attic or Crawl Space For Intake Air in Feet 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 - 4500 ft 2”...
  • Page 29 TYPICAL EXHAUST PIPE CONNECTIONS IN UPFLOW DIRECT OR NON-DIRECT VENT APPLICATIONS Pipe size determined in table 14 2” 3” 2” 2” 2” 2” TRANSITION EXHAUST *2” DO NOT transition from smaller to larger pipe in horizontal runs of exhaust pipe. * When transitioning up in pipe size, use the shortest length of 2”...
  • Page 30 TYPICAL AIR INTAKE PIPE CONNECTIONS IN UPFLOW DIRECT VENT APPLICATIONS Pipe size determined in table 14 2” 3” TRANSITION AIR INTAKE 2” *2” 2” 2” 2” * When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible. NOTE −...
  • Page 31 Intake Piping TYPICAL AIR INTAKE PIPE CONNECTIONS The ML195UH furnace may be installed in either direct HORIZONTAL NON−DIRECT VENT APPLICATIONS vent or non-direct vent applications. In non-direct vent (Horizontal Right−Hand Air Discharge Application Shown) applications, when intake air will be drawn into the furnace from the surrounding space, the indoor air quality must be considered and guidelines listed in Combustion, Dilution PVC pipe...
  • Page 32 General Guidelines for Vent Terminations CAUTION In Non‐Direct Vent applications, combustion air is taken If this unit is being installed in an application with from indoors and the flue gases are discharged to the out­ combustion air coming in from a space serviced by doors.
  • Page 33 TABLE 16 Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation In Unconditioned Space For Winter Design Temperatures Single - Stage High Efficiency Furnace Unit Input Size Winter Design Vent Pipe Temperatures °F (°C) Diameter 2 in. 32 to 21 (0 to -6) 2-1/2 in.
  • Page 34: Vent Termination Clearances

    ‡ 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. FIGURE 36...
  • Page 35 ‡ 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. FIGURE 37 Page 35...
  • Page 36 Details of Intake and Exhaust Piping Terminations for 3”(76mm) MAX. Inches(mm) SIZE TERMINATION Direct Vent Installations PIPE PER TABLE 17. NOTE - In Direct Vent installations, combustion air is taken UNCONDITIONED from outdoors and flue gases are discharged to outdoors. ATTIC SPACE 8”...
  • Page 37: Front View

    8. A multiple furnace installation may use a group of up to four terminations assembled together horizontally, as 12” shown in figure 44. EXHAUST (305MM) VENT 5-1/2” 5” (140mm) (127MM) 2” EXTENSION FOR 2” PVC INTAKE PIPE1” EXTENSION FOR 3” PVC PIPE 18”...
  • Page 38 FIELD FABRICATED WALL TERMINATION NOTE − FIELD−PROVIDED REDUCER MAY BE 2” (51mm) 3” (76mm) REQUIRED TO ADAPT LARGER VENT PIPE SIZE Vent Pipe Vent Pipe TO TERMINATION A− Minimum clearance above grade or average 12” (305 mm) 12” (305 mm) snow accumulation B−...
  • Page 39 Details of Exhaust Piping Terminations for Non‐Direct ML195UH NON-DIRECT VENT APPLICATION Vent Applications USING EXISTING CHIMNEY Exhaust pipes may be routed either horizontally through an SIZE TERMINATION STRAIGHT-CUT OR ANGLE-CUT IN DIRECTION outside wall or vertically through the roof. In attic or closet PIPE PER TABLE 17.
  • Page 40 Heating cable kit is NOTE - In upflow applications where side return available from Lennox in various lengths; 6 ft. (1.8m) - air filter is installed on same side as the conden­ kit no. 26K68; 24 ft. (7.3m) - kit no. 26K69; and 50 ft.
  • Page 41 ML195UH With Evaporator Coil Using A Separate Drain Condensate Trap With Optional Overflow Switch From Evaporator Coil Evaporator drain line required Horizontal Furnace 4” Min. to 5” Max.above condensate drain connection) Field Provided Vent (1” min. 2” max. above condensate connec­ tion) FurnaceCondensate Condensate...
  • Page 42 ML195UH with Evaporator IMPORTANT Coil Using a Common Drain Evaporator drain When combining the furnace and evaporator line required 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.
  • Page 43 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) Adapter 3/4 inch slip X 3/4 inch mpt (not furnished) Condensate Drain...
  • Page 44 TRAP / DRAIN ASSEMBLY USING 1/2” PVC OR 3/4” PVC COLD END HEADER BOX WITH 1/2” DRAIN CONNECTION 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) Adapter 1/2 inch slip X 1/2 inch mpt (Not Furnished) Condensate Drain...
  • Page 45: Iii-Start-Up

    III-START‐UP 2 - Set the thermostat to the lowest setting. 3 - Turn off all electrical power to the unit. A-Preliminary and Seasonal Checks 4 - This furnace is equipped with an ignition device which 1 - Inspect electrical wiring, both field and factory installed automatically lights the burners.
  • Page 46: Iv-Heating System Service Checks

    Gas Leak Detector is strongly recommended. It is 3 - While waiting for the unit to stabilize, observe the available through Lennox under part number 31B2001. flame. Flame should be stable and should not lift from See Corp. 8411-L10, for further details.
  • Page 47 TABLE 19 F-High Altitude Supply Line and Manifold Pressure (inches w.c.) At NOTE - In Canada, certification for installations at eleva­ All Altitudes For -1 Through -5 Units tions over 4500 feet (1372 m) is the jurisdiction of local au­ thorities.
  • Page 48: V-Typical Operating Conditions

    G- Proper Ground and Voltage CHECK VOLTAGE BETWEEN LINE HOT AND LINE NEUTRAL A poorly grounded furnace can contribute to premature ig­ nitor failure. Use the following procedure to check for ground and voltage to the integrated control. 1 - Measure the AC voltage between Line Neutral (spade terminals) and “C”...
  • Page 49: Vi-Maintenance

    TEMPERATURE RISE EXTERNAL STATIC PRESSURE Supply Duct Static ________ Supply Duct Temperature ________ Return Duct Static + _____ Return Duct Temperature _____ Temperature Rise = ________ Total Duct Static = ________ (dry coil) SUPPLY Supply Air Duct Static Temperature RETURN AIR Return Air FIGURE 64 FIGURE 63...
  • Page 50 1 - Turn off electrical and gas supplies to the furnace. against the data given in the appropriate Lennox 2 - Remove the burner access panel. Product Specifications bulletin. Additional informa­...
  • Page 51 13 - Disconnect the 2‐pin plug from the combustion air in­ 35 - Reinstall condensate trap pipe. Reconnect conden­ ducer. Remove screws which secure combustion air sate drain line to the condensate trap. inducer to collector box. Remove combustion air in­ 36 - Reinstall electrical junction box.
  • Page 52: Vii-Sequence Of Operation

    VII-WIRING DIAGRAM AND SEQUENCE OF OPERATION ML195UH With Integrated Control 100973 1 - When there is a call for heat, W1 of the thermostat en­ 5 - Gas valve opens for a 4-second trial for ignition ergizes W of the furnace control with 24VAC. 6 - Flame is sensed, gas valve remains open for the heat 2 - S10 primary limit switch and S47 rollout switch are call.
  • Page 53: Heating Sequence Of Operation

    Sequence of Operation Flow Chart - Integrated Control 100973 HEATING SEQUENCE OF OPERATION ABNORMAL HEATING MODE NORMAL HEATING MODE POWER ON GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER DELAY OFF. CONTROL SELF-CHECK OKAY? LED #1 ON LED #2 ON (RESET CONTROL BY TURNING MAIN POWER OFF.) POLARITY REVERSED.
  • Page 54 HEATING SEQUENCE CONTINUED NORMAL HEATING MODE ABNORMAL HEATING MODE 15‐SECOND COMBUSTION AIR INDUCER PREPURGE INITIATED BY CLOSED PRESSURE SWITCH. LEDS SIGNAL ALTERNATING FAST FLASH UNTIL IS VOLTAGE ABOVE 90 VOLTS? IGNITOR WARM‐UP -- 20 SECONDS. VOLTAGE IS ABOVE 95 VOLTS, THEN RESTARTS HEATING 4‐SECOND TRIAL FOR IGNITION.
  • Page 55 COOLING SEQUENCE OF OPERATION NORMAL COOLING MODE ABNORMAL COOLING MODE POWER ON IGNITION CONTROL MAIN POWER ON. GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER OFF WITH NORMAL DELAY. CONTROL SELF DIAGNOSTIC CHECK. SIGNAL CIRCUIT BOARD FAILURE AT LED. IS CONTROL OPERATING NORMALLY? INTERRUPT MAIN POWER TO RESET CONTROL.
  • Page 56 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. HUM TERM. ENERGIZES THERMOSTAT CALLS FOR HEAT (W). WITH COMB.
  • Page 57 ML195UH With Integrated Control 103085 1 - When there is a call for heat, W1 of the thermostat en­ 5 - Gas valve opens for a 4-second trial for ignition ergizes W of the furnace control with 24VAC. 6 - Flame is sensed, gas valve remains open for the heat 2 - S10 primary limit switch and S47 rollout switch are call.
  • Page 58 Sequence of Operation Flow Chart - Integrated Control 103085 HEATING SEQUENCE OF OPERATION ABNORMAL HEATING MODE NORMAL HEATING MODE POWER ON GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER DELAY OFF. CONTROL SELF-CHECK OKAY? LED: OFF POLARITY REVERSED. IS POLARITY CORRECT? LED: 9 FLASHES IMPROPER GROUND.
  • Page 59 HEATING SEQUENCE CONTINUED NORMAL HEATING MODE ABNORMAL HEATING MODE 15‐SECOND COMBUSTION AIR INDUCER PREPURGE INITIATED BY CLOSED PRESSURE SWITCH. LED: ON STEADY UNTIL VOLTAGE IS IS VOLTAGE ABOVE 90 VOLTS? IGNITOR WARM‐UP -- 20 SECONDS. ABOVE 95 VOLTS, THEN RESTARTS HEATING SEQUENCE.
  • Page 60 COOLING SEQUENCE OF OPERATION NORMAL COOLING MODE ABNORMAL COOLING MODE POWER ON IGNITION CONTROL MAIN POWER ON. LED: ON STEADY GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER OFF WITH NORMAL DELAY. CONTROL SELF DIAGNOSTIC CHECK. LED: OFF IS CONTROL OPERATING NORMALLY? INTERRUPT MAIN POWER TO RESET CONTROL.

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