Lennox 21Z11 Duct Smoke Detector Kit Supply or Return Air with Power Board and Single Sensor

The Lennox 21Z11 (Model 603408-11) is a duct-mounted smoke detector kit designed for supply or return air applications on Lennox commercial packaged HVAC units. This single-sensor kit includes everything needed for a complete field installation, providing critical smoke detection capability to help protect building occupants and equipment.

Compatible Units:

• KC, KG, KH series — sizes 024 through 090
• LG, LC, LH, LD series — sizes 036 through 074

Kit Includes:

• Smoke detector sensor (1)
• Smoke detector power board (1)
• Supply bracket and supply brace
• Return bracket and return brace (for KC, KG, and KH units)
• Power harness
• Supply or return air harness
• Jumper harness
• Metal sampling tube
• Plastic exhaust tube
• Magnet
• Sensor manufacturer's instructions
• #10-16 x 3/4" sheet metal screws
• #8-32 x 1" thread-forming screws

For applications requiring both supply and return air smoke detection with two sensors, see the Lennox 21Z12 (603408-12) dual-sensor kit. This kit (21Z11) is a field-installed accessory and replaces the earlier Lennox catalog number 53W78 (C1SNSR44AP1).