Page 1
08/12
*2P0812*
507010−01
*P507010-01*
E 2012 Lennox Industries Inc.
Dallas, Texas, USA
AIR FLOW
UPFLOW
AIR FLOW
AIR FLOW
HORIZONTAL RIGHT
HORIZONTAL LEFT
INSTALLATION
INSTRUCTIONS
ML193UH
MERIT
®
SERIES GAS FURNACE
UPFLOW / HORIZONTAL AIR DISCHARGE
507010−01
08/2012
Supersedes 06/2012
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
This is a safety alert symbol and should never be ignored.
When you see this symbol on labels or in manuals, be alert
to the potential for personal injury or death.
CAUTION
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
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 installer (or
equivalent), service agency or the gas supplier.
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ML193UH Gas Furnace 3. . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 3. . . . . . . . . . . . . . . . . . . . . . . .
Safety Information 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as a Construction Heater 4. . . . . . . . . . .
General 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution, Ventilation Air 5. . . . . . . . . . . . . . . .
Setting Equipment 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipe and Fittings Specifications 13. . . . . . . . . . . . . . . . . . .
Joint Cementing Procedure 15. . . . . . . . . . . . . . . . . . . . . .
Venting Practices 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vent Piping Guidelines 17. . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start Up 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Measurement 43. . . . . . . . . . . . . . . . . . . . .
Proper Combustion 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Altitude 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 46. . . . . . . . . . . . . . . . . . . . . . . . . .
Twinning the ML193UH 47. . . . . . . . . . . . . . . . . . . . . . . . . .
Service 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start Up Checklist 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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