Lennox International Inc. MERIT SERIES GAS FURNACE DOWNFLOW AIR DISCHARGE manual

Page 1 01/1 1 *2P0111* 506475−01 *P506475-01*  2010 Lennox Industries Inc. Dallas, T exas, USA AIR FLOW DOWNFLOW INST ALLA TION INSTRUCTIONS ML193DF MERIT ® SERIES GAS FURNACE DOWNFLOW AIR DISCHARGE 506475−01 01/201 1 Supersedes 10/2010 THIS MANUAL MUST BE LEFT WITH THE HOMEOWNER FOR FUTURE REFERENCE This is a safety alert symbol and should[...]

Page 2 ML193DF Unit Dimensions − inches (mm) AIR EXHAUST AIR OUTLET COMBUSTION AIR INT AKE FLOW 2 − 1/16 (52) GAS PIPING INLET (Either Side) ELECTRICAL INLET (Either Side) RETURN AIR OPENING FRONT VIEW SIDE VIEW TOP VIEW A B C 3/4 (19) 27 − 3/4 19 − 1/4 (489) 9 − 1/8 (232) Right 6 − 9/16 (167) Left 2 (51) Either Side 33 (838) 3/4 (19) B[...]

Page 3 ML193DF Part s Arrangement FIGURE 1 CONTROL BOX (Includes integrated control, transformer and door switch) BAG ASSEMBL Y BLOWER MOTOR (hidden) BLOWER ACCESS P ANEL BURNER ACCESS P ANEL COMBUSTION AIR INDUCER BURNER BOX ASSEMBL Y (includes sensor , rollout switches and ignitor) GAS V AL VE BLOWER DECK HEA T EXCHANGER COLD END HEADER BOX PRIMA[...]

Page 4 ML193DF Gas Furnace The ML193DF Categor y IV gas fur nace is shipped ready for installation in the downflow position. The furnace is equipped for i nstallation in natural gas ap- plications. A conversion kit (ordered separately) is re- quired for use in propane/LP gas applications. The ML193DF can be installed as a Direct V ent or Non− Dir[...]

Page 5 NOTE − Furnace must be adjusted to obtain a temperature rise within the range specified on the unit nameplate. Failure to d o s o may c ause erratic l i mit operation a nd premature h eat exchanger failure. This ML193DF furnace must be i nstalled so that it s electri- cal components are protected from water . Installation in Combination wi[...]

Page 6 General These instructions are intended as a general guide and do not supersede local codes in any way . Consult authorities having jurisdiction before installation. In addition to the requirement s outlined previously , the fol- lowing general recommendations must be considered when installing a ML193DF furnace: • Place the furnace as clo[...]

Page 7 All gas-fired appliances require air for the combustion pro- cess. If sufficient combustion air is not available, the fur- nace or other appliance will operate inefficiently and un- safely . Enough air must be provided to meet the needs of al l fuel−burning appliances and appliances such as exhaust fans w hich f orce a ir o ut of t he hous[...]

Page 8 FIGURE 5 EQUIPMENT IN CONFINED SP ACE − ALL AIR FROM OUTSIDE (Inlet Air from Crawl Space and Outlet Air to V entilated Attic) NOTE −The inlet and outlet air openings shall each have a free area of at least one square inch per 4,000 Btu (645mm 2 per 1.17kW) pe r hour of the tot al input rating of all equipment in the enclosure. OUTLET AIR[...]

Page 9 FIGURE 8 RIGID LEG remove shipping bolt and washer ML193DF09048C BLOWER MOTOR Inst allation − Setting Equipment W ARNING Do not install the furnace on it s front, back or in the horizontal position. See figure 10. Do not connect the return air duct s to the back of the furnace. Doing so will adversely affect the operation of the safety con[...]

Page 10 W ARNING Improper inst allation of the furnace can result in per- sonal injury or death. Combustion and flue product s mus t never be allowed to enter the return air system or air in the living sp ace. Use sheet met al screws and joint tape to seal return air system to furnace. In plat form installations with furnace return, the fur- nace s[...]

Page 11 T ABLE 2 COMBUSTIBLE FLOORING BASE OPENING SIZE Cabinet Width Catalog Number Front to Rear Side to Side in. mm in. mm B Cabinet (17.5") 1 1M60 22 559 18 − 3/4 476 C Cabinet (21") 1 1M61 22 559 22 − 3/4 578 FIGURE 13 FURNACE SUPPL Y AIR PLENUM COMBUSTIBLE FLOORING BASE PROPERL Y SIZED FLOOR OPENING 2 − Afte r opening is cut, [...]

Page 12 Filters This unit is not equipped with a filter or rack. A field−pro- vided filter is required for the unit to operate properly . T able 3 lists recommended filter size. A filter must be in place whenever the unit is operating. T ABLE 3 Furnace Cabinet Width Filter Size 16 x 25 x 1 (1) 17−1/2" 21" Duct System Use industry-appr[...]

Page 13 IMPORT ANT ML193DF exhaust and int ake 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 P VC p r imer a nd solvent c ement o r A BS s olv ent c ement meeting ASTM specifications, refer to[...]

Page 14 Joint Cementing Procedure All cementing of joint s should be done according to the specifications outlined in ASTM D 2855. NOTE − A sheet met al screw may be used to secure the i ntake pipe to the connector , if desir ed. U s e a drill or self t apping screw to make a pilot hole. DANGER DANGER OF EXPLOSION! Fumes from PVC glue may ignite [...]

Page 15 2 − When furnac e is ins talled in a residence wher e unit is shut down for an extended period of time, suc h as a vacation home, make pr ovisions for draining conden- sate collection trap and lines. Exhaust Piping (Figures 20 and 21) Route p ipi ng to o ut side of structure. Continue with inst alla - tion following instructions given in [...]

Page 16 T ABLE 7 Maximum Allowable Intake or Exhaust V ent Length in Feet *Siz e intake and exhaus t pipe length separately . Values in table are for Intake OR Ex haust, not combined total. Both Intak e an d Exhaust must be same pipe size. St andard T ermination at Elevation 0 − 10,000 ft. Number Of 90° Elbows Used 2" Pipe 2−1/2" Pip[...]

Page 17 FIGURE 20 TYPICAL EXHAUST PIPE CONNECTIONS TRANSITION 2” 2” 2” 3” Pipe size determined in table 7. 2” 2” or DO NOT transition from smaller to larger pipe size in horizontal runs of exhaust pipe. TOP VIEW EXHAUST INTAKE * When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible. NOTE − Exhaust pipe [...]

Page 18 Intake Piping The ML193DF furnace may be installed in either direct vent or non−direct vent applications. In non−dir ect vent applications, w hen intake a ir will b e drawn into the f ur nace from t he surrounding sp ace, t he i ndoor a ir q uality m us t b e considered. G uidelines listed in Combustion, D ilution a nd V entilation Air [...]

Page 19 FIGURE 23 VENT TERMINA TION CLEARANCES FOR NON−DIRECT VENT INST ALLA TIONS IN THE USA AND CANADA K D E L B C F G A B J A M I H INSIDE CORNER DET AIL VENT TERMINAL AIR SUPPL Y INLET AREA WHERE TERMINAL IS NOT PERMITTED Fixed Closed Operable B Fixed Closed Operable B B A = B = C = D = E = F = G = H = I = J = K = L = M = US Installations 1 C[...]

Page 20 FIGURE 24 VENT TERMINA TION CLEARANCES FOR DIRECT VENT INST ALLA TIONS IN THE USA AND CANADA K D E L B C F G A B J A M I H INSIDE CORNER DET AIL VENT TERMINAL AIR SUPPL Y INLET AREA WHERE TERMINAL IS NOT PERMITTED Fixed Closed Operable B Fixed Closed Operable B B A = B = C = D = E = F = G = H = I = J = K = L = M = US Installations 1 Canadia[...]

Page 21 Det ails of Int ake and Exhaust Piping T erminations for Direct V ent Installations NOTE − In D irect V ent i nstallations, combustion air is ta k- en from outdoors and flue ga ses are discharged to out - doors. NOTE − Flue gas may be slightly acidic and may adversely affect some building materials. If any vent termination is used and t[...]

Page 22 FIGURE 27 C A E D B A B D D B C A C 12" 1 1 2 2 2" (51mm) V ent Pipe 3" (76mm) V ent Pipe 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 −W all support distance from top of each pipe[...]

Page 23 FIGURE 28 FIELD SUPPLIED W ALL TERMINA TION OR (15F74) W ALL RING TERMINA TION KIT See venting table 7 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 6"[...]

Page 24 FIGURE 30 DIRECT VENT CONCENTRIC ROOFTOP TERMINA TION 71M80, 69M29 or 60L46 (US) 41W92 or 41W93 (Canada) Minimum Above Average Snow Accumulation SHEET MET AL STRAP (Clamp and sheet metal strap must be field installed to support the weight of the termination kit.) FLASHING (Not Furnished) CLAMP FIELD−PROVIDED REDUCER MA Y BE REQUIRED TO AD[...]

Page 25 FIGURE 35 12” (305 mm) Minimum Above Grade or Average Snow Accumulation 1/2” (13 mm) FOAM INSULA TION (Field Furnished) 5” (127 mm) 5 − 1/2” (140 mm) EXHAUST AIR INT AKE AIR GRADE 12” (305 mm) INT AKE AIR EXHAUST AIR GRADE 12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust 20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust WALL SU[...]

Page 26 ML193DF DIRECT VENT APPLICA TION USING EXISTING CHIMNEY 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[...]

Page 27 FIGURE 40 12" (305mm) ABOVE GRADE OR A VERAGE SNOW ACCUMULA TION UNCONDITIONED SP ACE 1/2" (13mm) FOAM INSULA TION 1/2" (13mm) FOAM INSULA TION IN UNCONDITIONED SP ACE *W ALL SUPPORT OUTSIDE W ALL SIZE TER- MINA TION PIPE PER T ABLE 8. FIELD−PROVIDED REDUCER MA Y BE REQUIRED TO ADAPT LARGER VENT PIPE SIZE TO TERMINA TION *U[...]

Page 28 5 − If unit will be started immediately upon completion of installation, pr ime trap per proc edure outlined in Unit S tart−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 sp a[...]

Page 29 FIGURE 45 Adapter 1/2 inch slip X 1/2 inch mpt (Not Furnished) Drain T rap Assembly (Furnished) V ent Drain T rap Clean Out 5 Feet Maximum Coupling 1/2 inch slip X slip (Not Furnished) 90 ° Elbow 1/2 inch PVC (Not Furnished) 1/2 inch PVC Pipe (Not Furnished) 1/2 inch PVC Pipe (Not Furnished) 1 (25) Minimum Above T op of Condensate Drain Co[...]

Page 30 Gas Piping CAUTION If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall b e inst alled at the gas valve and extend out side the furnace cabinet. The flexible connector can then be added between the black iron pipe and the gas supply line. W ARNING Do not exceed 600 in−lbs (50 ft?[...]

Page 31 GROUND JOINT UNION AUTOMA TIC GAS V AL VE (with manual shut−off valve) FIELD PROVIDED AND INST ALLED GROUND JOINT UNION Left Side Piping (St andard) Right Side Piping (Alternate) AUTOMA TIC GAS V AL VE (with manual shut−off valve) DRIP LEG DRIP LEG MANUAL MAIN SHUT−OFF VA LV E (With 1/8 in. NPT Plugged T ap Shown) MANUAL MAIN SHUT−O[...]

Page 32 Removal of the Furnace from Common V ent In the event that an existing furnace is removed from a venting system commonly ru n with separate gas ap- pliances, the venting system is likely to be too large to properly vent the remaining attached appliances. Conduct t he f ollowing t est w hile each appliance is operat- ing and the o ther appli[...]

Page 33 FIGURE 48 MAKE−UP BOX INSIDE CABINET Left side INTERIOR MAKE−UP BOX (F ACTOR Y− INST ALLED LEFT SIDE) FIGURE 49 MAKE−UP BOX OUTSIDE CABINET Right Side EXTERIOR MAKE−UP BOX (FIELD PROVIDED RIGHT SIDE) Refer t o figure 51 for field wiring and figure 5 2 for schematic wiring diagram and troubleshooting. The power supply wiring must m[...]

Page 34 Thermostat Furnace Condensing Unit ML193DF and CONDENSING UNIT THERMOST A T DESIGNA TIONS (Refer to specific thermostat and out door unit.) COMMON POWER HEA T INDOOR BLOWER Y C R G W1 Y C R G W COOLING FIGURE 50 CONDENSING UNIT CONDENSING UNIT COMMON *CONDENSING UNIT *NOTE − R" REQUIRED ON SOME OUTDOOR UNITS Install the r[...]

Page 35 TYPICAL ML193DF WIRING DIAGRAM FIGURE 52[...]

Page 36 FIGURE 53 INTEGRA TED CONTROL (Automatic Hot Surface Ignition System) TERMINAL DESIGNA TIONS HUM LINE XFMR EAC COOL HEA T P ARK FLAME NEUTRALS Humidifier (120V AC) Input (120V AC) Transformer (120V AC) Electronic Air Cleaner (120V AC) Blower − Cooling S peed (120V AC) Blower − Heating S peed (120V AC) Dead terminals to park alternate sp[...]

Page 37 Placing the furnace into operation: ML193DF unit s are equipped with an automatic hot sur- face ignition system. 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 thes e units. Priming Conden[...]

Page 38 Gas Pressure Adjustment Gas Flow (Approximate) T ABLE 1 1 GAS METER CLOCKING CHART ML193 Unit Seconds for One Revolution Natural LP 1 cu ft Dial 2 cu ft Dial 1 cu ft Dial 2 cu ft DIAL −045 80 160 200 400 −070 55 11 0 136 272 −090 41 82 102 204 −1 10 33 66 82 164 Natural−1000 btu/cu ft LP−2500 btu/cu ft NOTE − T o obtain accura[...]

Page 39 T ABLE 14 Conversion Kit and Pressure Switch Requirements at V arying Altitudes ML193 Unit Natural to LP/Prop ane High Altitude Natural Burner Orifice Kit LP/Prop ane to Natural High Altitude LP/Prop ane Burner Orifice Kit High Altitude Pressure Switch 0 − 7500 ft (0 − 2286m) 7501 − 10,000 ft (2286 − 3038m) 0 − 7500 ft (0 − 2286[...]

Page 40 Other Unit Adjustment s NOTE − See troubleshooting flow charts if any safety switches are found to be open. Primary Limit The primary limit is located on the heating compartment vestibule p an el. This limi t is facto ry set and requires no ad- justment. Flame Rollout Switches (T wo) These manually reset switches are located on the front [...]

Page 41 BLOWER DA T A ML193DF070P36B PERFORMANCE (Less Filter) External Static Pressure in. w .g. Air V olume / Watts at V arious Blower Speeds High Medium- High Medium- Low Low cfm W atts cfm W atts cfm Watts cfm W atts 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[...]

Page 42 Service W ARNING ELECTRICAL SHOCK, FIRE, OR EXPLOSION HAZARD. Failure t o 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 fu[...]

Page 43 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. Reinst[...]

Page 44 Planned Service A service technician should check the following items dur- in g an annual inspection. Power to the unit must be shut off for safety . Fresh air grilles and louvers (on the unit and in the room where the furnace is installed) − Must be open and unob- structed to provide combustion air . Burners − Must be i ns pected for r[...]

Page 45 T roubleshooting: Heating Sequence of Operation HEA TING SEQUENCE OF OPERA TION NORMAL HEA TING MODE ABNORMAL HEA TING MODE CONTROL SELF−CHECK OKA Y? BURNER OFF? (Flame sensed without gas valve energized) NORMAL OPERA TION: LED #1 −− SLOW FLASH LED #2 −− SLOW FLASH NO YES YES GAS V AL VE OFF . COMBUSTION AIR INDUCER OFF . INDOOR B[...]

Page 46 T roubleshooting: Heating Sequence of Operation (Continued) HEA TING SEQUENCE CONTINUED NORMAL HEA TING MODE ABNORMAL HEA TING MODE FLAME RECTIFICA TION CURRENT CHECK. CAN FLAME BE PROVEN WITHIN 4 SECONDS AFTER GAS V AL VE OPENS? (0.5 microamps) FLAME PRESENT? INDOOR BLOWER ON AFTER 30−SECOND DELA Y PRIMARY AND SECONDARY LIMIT SWITCHES CL[...]

Page 47 T roubleshooting: Cooling Sequence of Operation COOLING SEQUENCE OF OPERA TION NORMAL COOLING MODE ABNORMAL COOLING MODE IGNITION CONTROL MAIN POWER ON. CONTROL SELF DIAGNOSTIC CHECK. IS CONTROL OPERA TING NORMALL Y? YES SIGNAL POLARITY REVERSED A T LED. CONTROL WILL CONTINUE TO CALL FOR COOLING IN THIS CONDITION. POWER ON GAS V AL VE OFF .[...]

Page 48 T roubleshooting: Continuous Fan Sequence of Operation CONTINUOUS HEA T SPEED F AN SEQUENCE OF OPERA TION LED: SLOW FLASH RA TE REMAINS UNCHANGED THROUGHOUT SEQUENCE. MANUAL F AN SELECTION MADE A T THERMOST A T . CONTROL (G) ENERGIZES SYSTEM F AN A T HEA T SPEED. EAC TERMINAL IS ENERGIZED. THERMOST A T CALLS FOR HEA T (W). THERMOST A T CALL[...]

Page 49 Rep air Part s List The following repair parts are available through Lennox dealers. When ordering parts, include the complete furnace model numb er listed on the CSA nameplate −− Example: ML193DF04536B. All service must be performed by a licensed pro- fessional inst aller (or equivalent), service agency , or gas supplier . Cabinet Part[...]

Page 50 St art−Up & Performance Check List Gas Supply Pressure SUPPL Y AIR Line V oltage GAS SUPPL Y Natural Gas LP Propane Gas Piping Connections Tight Leak T ested Supply Line Pressure W .C.________ 1 INT AKE / EXHAUST PIPE All Joints Primed and Glued T erminations Installed Properly Pipes Supported Condensate T rap Primed / Line Sloped [...]

Page 51 Contractor’s: Name_________________________T elephone_____________Checklist Completed____________________ Job Address_____−________________________________T echnician’s Name___________________________________ 1 HEA TING MODE GAS MANIFOLD PRESSURE W .C._____ COMBUSTIO N SAMPLE CO 2 % ______ CO PPM_______ 2 INDOOR BLO WER AMPS______ [...]

Page 52 Requirement s for Commonwealth of Massachusett s Modifications to NFP A−54, Chapter 10 Revise N FP A− 54 section 10.8.3 to add the following re- quirement s: Fo r all side wall, horizontally vented, gas−fueled equipment installed in every dwelling, building or structure used in whole or in p art for residential purposes, including tho[...]