Lennox MERIT ML180UHE Installation Instructions Manual page 32

HEAT FAN-OFF TIME IN SECONDS
NO JUMPER
To adjust fan−off timing, reposition jumper across pins to
achieve desired setting.
60 Second 90 Second
off Time off Time
FIGURE 36
Thermostat Heat Anticipation
Set the heat anticipator setting (if adjustable) according to
the amp draw listed on the wiring diagram that is attached
to the unit.
Constant Torque Motor
ML180UHE units are equipped with a constant torque ECM
motor. It has a DC motor coupled to an electronic control
module both contained in the same motor housing. The mo-
tor is programmed to provide constant torque at each of the
five selectable speeds. The motor has five speed taps.
Each tap requires 24 volts to energize.
120 Second 180 Second
off Time off Time
Page 32
Input Voltage Requirements
The circuit is designed to be operated with AC voltage. A
voltage of 12 to 33VAC is required to energize the motor.
Expected current draw will be less than 20mA.
Blower Speeds
Follow the steps below to change the blower speeds.
1 − Turn off electrical power to furnace.
2 − Remove blower access panel.
3 − Disconnect existing speed tap at integrated control
speed terminal.
NOTE − Termination of any unused motor leads must be
insulated.
4 − Place unused blower speed tap on integrated control
PARK" terminal or insulate.
5 − Refer to blower speed selection chart on unit wiring dia-
gram for desired heating or cooling speed. See Blower
performance data beginning on the next page.
6 − Connect selected speed tap at integrated control
speed terminal.
7 − Resecure blower access panel.
8 − Turn on electrical power to furnace.
9 − Recheck temperature rise.
Electronic Ignition
The integrated control has an added feature of an internal
Watchguard control. The feature serves as an automatic re-
set device for integrated control lockout caused by ignition
failure. This type of lockout is usually due to low gas line
pressure. After one hour of continuous thermostat demand
for heat, the Watchguard will re−set and remake thermostat
demand to the furnace and automatically reset the inte-
grated control to begin the ignition sequence.