Lennox PRODIGY M2 User Manual

7. Economizer
Page 26
506457−01 05/10
7.6. Outdoor Air Suitability
There are six options available to determine outdoor air suitability (OAS) for free cooling. See table 24. Economizer settings
are shown for each mode in figure 9.
The appropriate sensors are provided when the economizer is factory−configured. When the economizer is field−configured,
the ODE mode requires additional field−provided sensor(s). See table 24. The TEMP mode uses sensors provided with all
units.
Table 24. Free Cooling Options
Free cooling mode
DIP SW
positions
MODE
Selection
CONTROL
Selection
OAS setpoint calc if
CONTROL is SENSIBLE
Temperature offset 1,2 to TMP TEMP OFFSET OAT<RAT−OFFSET (0 to 40 F)
Temperature setpoint 1,2 to TMP TEMP OAT STPT OAT<OAT STPT (41 to 70 F)
Remote 1,2 to TMP TEMP ANY OAS sent by network.
Enthalpy differential (Potentiometer set to DIFF) 1,2 to ODE ENTH N/A ODE<IDE
Enthalpy setpoint (Potentiometer set to A−D) 1,2 to ODE ENTH N/A ODE<POT
Global input 1,2 to GLO GLOBAL N/A GLO input
Note−All economizer modes of operation, except DSET, will modulate dampers to 55°F (13°C) discharge air.
ODE DIFFERENTIAL
(Outdoor Enthalpy)
GLO
(Global Enthalpy)
ODE
(Outdoor Enthalpy)
Set to DIF
A
B
C
D
DIF
ENTH SET PNT
A
B
C
D
DIF
Set to A
ENTH SET PNT
TEMP OFFSET,
TEMP OAT STPT, and
Remote MODE.
Figure 9. Economizer free cooling settings
7.7. Enthalpy Setpoint
This setting pertains to the ODE free cooling mode only. The M2 will enable free cooling when outdoor air enthalpy (A7) is
less than the enthalpy setpoint. Table 25 shows the approximate enthalpy setpoints for each potentiometer setting at 50%
relative humidity.
Table 25. Enthalpy Control Setpoints
The recommended enthalpy setpoint is

A
"
If the
Control
Setting
Enthalpy Control Setpoint At 50% Relative Humidity
Approximate Degrees F (C)
The recommended enthalpy setpoint is A". If the
economizer is allowing air which is too warm or too
A 73 (23)
economizer
is
allowing
air
which
is
too
warm
or
too
humid to enter the system, the enthalpy control may
B 70 (21)
humid
to
enter
the
system,
the
enthalpy
control
may
be changed to a lower setting (B, C, or D).
C 67 (19)
D 63 (17)
Example:At setting A", the enthalpy control will modulate dampers open when outdoor air is at 73°F and 50% relative
humidity. If space temperatures are too warm, rotate the potentiometer to B". The enthalpy control will now modulate damp-
ers open when outdoor air is 70°F and 50% relative humidity.

Lennox PRODIGY M2 Specifications

General

Brand	Lennox
Model	PRODIGY M2
Category	Controller
Language	English