Lennox sequences of operation

11 sequences for Lennox equipment: what the unit does, step by step, with the timings. Pick the equipment type, then the mode.

Furnace (8)

Ignition

• Single-stage furnace ignition retries and watchguard
  EL195UHNE, ML180UHEK
• Two-stage furnace ignition retries and watchguard
  EL296UHV, SL280UHV, SL280UHNV

Heating

• Single-stage furnace gas heating cycle
  EL195UHNE, ML180UHEK
• Two-stage furnace heating with single-stage thermostat
  EL296UHV, SL280UHV, SL280UHNV
• Two-stage variable speed furnace heating with two-stage thermostat
  EL296UHV, SL280UHV, SL280UHNV

Cooling

• Cooling call on single-stage furnace blower
  EL195UHNE, ML180UHEK
• Two-stage variable speed cooling call
  SL280UHV, SL280UHNV

Standby/shutdown

• Continuous fan with heat or cool calls
  EL195UHNE, ML180UHEK

Heat pump (3)

Heating

• Heat pump first-stage heating
  ML14KP1, EL16KP1

Cooling

• Heat pump cooling call
  ML14KP1, EL16KP1

Defrost

• Demand defrost cycle
  ML14KP1, EL16KP1

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.