Page 1
07/11
*2P0711*
506723−01
*P506723-01*
E 2011 Lennox Industries Inc.
Dallas, Texas, USA
AIR FLOW
UPFLOW
AIR FLOW
AIR FLOW
HORIZONTAL RIGHT
HORIZONTAL LEFT
INSTALLATION
INSTRUCTIONS
ML195UH
MERIT
®
SERIES GAS FURNACE
UPFLOW / HORIZONTAL AIR DISCHARGE
506723−01
07/2011
Supersedes 506533−01
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ML195UH Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . .
ML195UH Gas Furnace 4. . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . . . .
Safety Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as a Construction Heater 5. . . . . . . . . . .
General 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution, Ventilation Air 6. . . . . . . . . . . . . . .
Setting Equipment 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipe and Fittings Specifications 13. . . . . . . . . . . . . . . . . . .
Joint Cementing Procedure 15. . . . . . . . . . . . . . . . . . . . . . .
Venting Practices 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vent Piping Guidelines 17. . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start Up 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Measurement 42. . . . . . . . . . . . . . . . . . . . . .
Proper Combustion 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Altitude 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 44. . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Motor Performance 45. . . . . . . . . . . . . . . . . . . . . . .
Service 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Planned Service 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control Diagnostic Codes 49. . . . . . . . . . . . . . .
Troubleshooting 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start Up Checklist 54. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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