

GAS UNITS

KITS & ACCESSORIES

Litho U.S.A.

E 2002 Lennox Industries Inc.

Dallas, Texas 504,450M

1/2002

POST-PURGE TIMER KIT

INSTALLATION INSTRUCTIONS FOR POST-PURGE TIMER KIT (21M88)

USED WITH LENNOX GAS FURNACES

Shipping and Packing List

Package 1 of 1 contains:

1 - Timer

2 - 36" red wires

2 - Wire nuts

1 - Sheet metal screw

1 - Wiring diagram

1 - Installation instruction

Application

Post-purge timer kit (21M88) is available for installation on Lennox gas furnaces. The timer adds 30 seconds to the post-purge period at the end of the heat cycle.

WARNING

These instructions must be followed exactly. This kit must be installed by a qualified service techniĆ cian. Improper installation may result in personal injury, loss of life or equipment damage.

Installation

WARNING

Timer must be wired in parallel with the 120VAC hot terminal on the unit control board and the switched terminal on the combustion air inducer as shown in the field wiring diagram. If wire is connected to the neutral terminal on the combustion air inducer, a diĆ rect short will be created, resulting in damage to the timer and/or unit control board.

FIELD WIRING DIAGRAM

WARNING

Beforeattempting to perform any service or mainĆ tenance, turn the electrical power OFF to unit at disconnect switch(es). Turn off gas supply to unit at main manual shut-off valve.

1 - Remove heating compartment / unit access panel.

2 - Use provided screw to install timer in the unit control box.

3 - Connect one of the provided red wires to terminal 1 on the timer and to the combustion air inducer motor

(B6). See figure 1.

4 - Connect the other provided red wires to terminal 3 on the timer and to the 120VAC HOT terminal on the unit control board. See figure 1.

FIGURE 1

5 - Apply adhesive-backed field wiring diagram in conspicuous location near unit wiring diagram.

6 - Replace the unit access panel(s) and restore gas and electrical supplies to furnace.

7 - Proceed with unit start-up.

Operation

The post-purge timer (DL36) brings the combustion air inducer on for an additional 30 seconds of operation at the end of each heating cycle.

01/02

*2P0102*

504,450M

*P504450M*