Page 1
INSTALLATION
INSTRUCTIONS
ML180DF
507326-02
11/2017
Supersedes 05/2016
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 man-
uals, be alert to the potential for personal injury or death
CAUTION
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal
injury or loss of life. Installation and service must be
performed by a licensed professional HVAC installer or
equivalent, service agency, or the gas supplier.
© 2017 Lennox Industries Inc.
Dallas, Texas USA
MERIT® SERIES GAS FURNACE
DOWNFLOW AIRDISCHARGE
Contents
Unit Dimensions .............................................................2
ML180DF Gas Furnace ..................................................3
Shipping and Packing List ..............................................3
Safety Information ..........................................................3
Use of Furnace as Construction Heater .........................4
General ...........................................................................4
Combustion, Dilution & Ventilation Air ............................5
Setting Equipment .........................................................9
Filters ............................................................................10
Duct System ................................................................. 11
Venting.......................................................................... 11
Gas Piping ....................................................................16
Electrical .......................................................................18
Integrated Control .........................................................21
Unit Start Up .................................................................22
Gas Pressure Adjustment .............................................23
Proper Combustion.......................................................23
High Altitude .................................................................23
Other Unit Adjustments.................................................24
Service..........................................................................26
Repait Parts ..................................................................28
DOWNFLOW
AIR FLOW
