W7212, W7213, W7214 ECONOMIZER LOGIC MODULES
9
63-2596—09
4.
Ensure that either the factory-installed jumper is in place
across terminals P and P1 or, if remote damper position
is required, that it is wired according to Fig. 6 and the
MIN POS potentiometer is turned fully clockwise.
5.
Connect 24 Vac across terminals TR and TR1.
6.
Carefully adjust the potentiometer on the face of the
device with a small screwdriver until the mixed air
temperature reaches the calculated value.
NOTE: Ensure that the sensed air is well mixed.
7.
If all minimum (MIN POS) and maximum position (DCV
MAX) adjustments are complete, remove the T-T1
jumper and reconnect the mixed air sensor.
Equation 1.Formula to aid minimum position adjustment.
Where:
T
O
= Outdoor air temperature
OA = Percent of outdoor air
T
R
= Return air temperature
RA = Percent of return air
T
M
= Resulting mixed air temperature
NOTE: The following sample calculation uses only
Fahrenheit temperature.
EXAMPLE: Assume local codes require 10% outdoor air dur-
ing occupied conditions, outdoor air is 60°F and
return air is 75°F. Under these conditions, what is
the temperature of the mixed air?
Mixed air will be 73.5°F when OA is 60°F and RA is 75°F with
10 percent outdoor air entering the building.
NOTE: If setting MIN POS and DCV MAX position, you will
need to adjust the MIN POS for the building effluent
(low occupancy) airflow and adjust the DCV MAX
using the minimum airflow for maximum occupancy.
Enthalpy Changeover Setpoint
Outdoor Enthalpy Changeover Setpoint
(Single Enthalpy)
Single enthalpy compares the outdoor air conditions to a set
A,B,C, or D (E) curve for humidity and temperature conditions.
The installer must set the onboard potentiometer to the desired
curve. The outdoor enthalpy changeover setpoint returns the
outdoor air damper to minimum position. Enthalpy setpoint
scale markings, located in the device, are A, B, C, and D for
the W7212A, W7213 and W7214. See Fig. 7 for the
corresponding control point. Enthalpy setpoint scale markings
for the W7212C are A,B,C,D and E. See Fig. 8 for the
corresponding control points. The factory-installed 620-ohm
jumper must be in place across terminals SR and SR+.
Temperature and humidity conditions to the left of the selected
curve will allow the dampers to open for free cooling,
temperature, and humidity conditions to the right of the curve
will return the OA damper to minimum position (this is either
MIN POS if using a CO2 sensor or DCV MAX if a CO2 sensor
is NOT used).
Differential Enthalpy Changeover Setting
Differential enthalpy control uses two C7400 Enthalpy Sensors
connected to one logic module. The logic module compares
outdoor air to return air.
NOTE: Turn the enthalpy setpoint potentiometer fully clock-
wise to the D (or E setting for W7212C) setting.
The logic module selects the lower enthalpy air (return or
outdoor) for cooling. For example, when outdoor air has lower
enthalpy than return air, the module calls to open the outdoor
air damper to bring in outdoor air for free cooling.
Exhaust Setpoint
The exhaust setpoint determines when the exhaust fan runs
based on damper position. When the exhaust fan call is made,
the module provides a 60 ±30 second delay before exhaust fan
activation. This delay allows the damper to reach the
appropriate position to avoid unnecessary fan overload.
NOTES:
—
EF and EF1 are 24V dry contacts only. An external
line voltage contactor is required to operate the
exhaust fan.
—
When the exhaust fan is deactivated the EF and
EF1 contacts open immediately.
Adjustable Exhaust Setpoint
These logic modules have an adjustable exhaust setpoint. This
potentiometer allows the installer to adjust the damper position
at which the EF and EF1 exhaust fan contacts are made.
NOTE: The 60 ±30 second delay allows the outdoor damper
to reach the exhaust setpoint prior to the EF and EF1
contacts being made.
Remote Minimum Position Control
Remote control of outdoor air dampers is desirable when
requiring temporary additional ventilation. The addition of a
S963B1128 Remote Potentiometer allows occupants to open
or close the dampers beyond minimum position for modified
ventilation. Connect the potentiometer as shown in Fig. 6. For
economizer applications using remote position potentiometers,
the action of the outdoor damper matches the MIN POS action
in Table 1.
IMPORTANT
Freeze protection logic takes priority over all signals.
For details, see the notes in the Adjusting Minimum
and Maximum Positions section.
NOTE: For additional wiring applications, refer to the Design
and Application Guide for Honeywell Economizers
(form 63-8594).
T
O
OA
×
(
)
T
R
RA
×
(
)
+
T
M
=
0.1 60°F
×
(
)
0.9 75°F
×
(
)
+
6.0°F 67.5°F
+
73.5°F
=
=
