E 2010 Lennox Industries Inc.
Dallas, Texas, USA
DOWNFLOW
AIR FLOW
INSTALLATION
INSTRUCTIONS
ML193DF
MERIT® SERIES GAS FURNACE
DOWNFLOW AIR DISCHARGE
506475−01 01/2011
Supersedes 10/2010
Litho U.S.A.
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
ML193DF Parts Arrangement . . . . . . . . . . . . . . . . . . . . . 3
ML193DF Gas Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Shipping and Packing List . . . . . . . . . . . . . . . . . . . . . . . . 4
Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Use of Furnace as a Construction Heater . . . . . . . . . . . 5
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Combustion, Dilution and Ventilation Air | 6 |
Setting Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Duct System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Pipe and Fittings Specifications . . . . . . . . . . . . . . . . . . . 12
Joint Cementing Procedure . . . . . . . . . . . . . . . . . . . . . . 14
Venting Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
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Vent Piping Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Unit Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Gas Pressure Measurement . . . . . . . . . . . . . . . . . . . . . 38 Proper Combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 High Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Testing Non Direct Appliances for Proper Air . . . . . . . 39 Other Unit Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Blower Motor Performance . . . . . . . . . . . . . . . . . . . . . . . 41 Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Planned Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Integrated Control Diagnostic Codes . . . . . . . . . . . . . . 44 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Repair Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Start Up Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
506475−01
