Lennox International Inc. o23v - Manual (Page 5)

Page 5
ADJUST
The ADJUST pins allow the motor to run at approximately
15% higher, or approximately 15% lower, than normal
speed. Tables 1, 2 and 3 give three rows (+, NORM, and −)
with their respective CFM volumes. Notice that the normal
(NORM) adjustment setting for cool speed position C in
table 1 is 800 CFM. The + adjustment setting for that posi-
tion is 920 CFM (115% of 800 CFM) and for the − adjust-
ment setting is 680 CFM (85% of 800 CFM). After the ad-
justment setting has been determined, choose the
remaining speed settings from those offered in the table in
that row.
The TEST pin is available to bypass the blower control and
run the motor at approximately 70% to make sure that the
motor is operational. This is used mainly in troubleshoot-
ing. The G terminal must be energized for the motor to run.
COOL
The COOL jumper is used to determine the CFM during
cooling operation. This jumper selection is activated for
cooling when Y1 is energized. Y1 and Y2 must be jump-
ered for single stage cooling.
The blower motor runs at 82% of the selected air flow for
the first 7−1/2 minutes of each cooling demand. This fea-
ture allows for greater humidity removal and saves energy.
OFF CALL
100%
82%
Y
60
sec 7.5 minutes
82%
y
Y − Cool Demand Present
y − Cool Demand Satisfied
When the demand for cool is met, the blower ramps down
to 82% for 60 seconds, then turns off.
HEAT
The HEAT jumper is used to determine CFM during heat
operation only. These jumper selections are activated only
when W1 is energized.
During the heat ON delay, the blower runs at 13% CFM for
the first minute, 50% for the second minute, and full CFM
after two minutes.
OFF CALL
100%
82%
50%
13%
W
60
sec 60
sec 210 seconds
w
W − Heat Demand Present
w − Heat Demand Satisfied
When the demand for heat is met, the blower ramps down
to 82% for 3−1/2 minutes, then turns off.
Continuous Fan
When the thermostat is set for Continuous Fan" operation
and there is no demand for heating or cooling, the blower
control will provide 50% of the COOL CFM selected.
OFF CALL
50%
G
g
G − Fan switch ON
g − Fan switch OFF
When a continuous fan is on (G demand present), the fan
runs at 50% until switched off; there is no ramp up or off de-
lays.
NOTE − With the proper thermostat and subbase, continu-
ous blower operation is possible by closing the R to G cir-
cuit.
Dehumidification
The A54 blower control board (see figure 2) includes a
HUM terminal which provides for connection of a humidis-
tat. The JW1 resistor on the blower control board must be
cut to activate the HUM terminal. The humidistat must be
wired to open on humidity rise. When the dehumidification
circuit is used, the variable speed motor will reduce the se-
lected air flow rate by 18% when humidity levels are high.
An LED (D1) lights when the blower is operating in the de-
humidification mode.
Humidification
Terminals are provided on the A15 control board for 120
volt output to operate a humidifier. The HUM" terminal is
energized when there is a call for heat. See unit wiring dia-
gram.
Electronic Air Cleaner
Terminals are provided on A15 control board for 120 volt
output to an electronic air cleaner. The EAC" terminal is
energized when there is a call for heat, cool, or continuous
blower. See unit wiring diagram.