C7400 Enthalpy Sensor And C7660 Dry Bulb Temperature Sensor; Demand Control Ventilation; Outdoor Air Sensing; Return Air Sensing - Honeywell W7212 Product Data

W7212, W7213, W7214 ECONOMIZER LOGIC MODULES
Fig. 3. Mounting the module on sheet metal.
C7400 Enthalpy Sensor and
C7660 Dry Bulb Temperature Sensor
W7212, W7213, W7214 Logic Modules accept signals from
either the C7400 Enthalpy Sensor or the C7660 Dry Bulb
Temperature Sensor. The W7212A, W7213 and W7214
models are used with the C7400A sensor and the W7212C
models are used with the C7400C sensor. The wiring is the
same for either sensor.
IMPORTANT
When using differential sensing, both sensors must
be of the same type.
For differential dry bulb operation use two C7650 sen-
sors. Note for referential dry bulb use only the C7660
dry bulb sensor for the most energy savings.

OUTDOOR AIR SENSING

1. Mount sensor in any orientation exposing it to freely
circulating air while protecting it from rain, snow, and
direct sunlight.
2. Connect it to the SO and SO+ terminals of the device.
63-2596—09

RETURN AIR SENSING

1. Ensure differential enthalpy control has a second
2. Connect this sensor to the SR and SR+ terminals.
3. Ensure sensor is mounted in the return air duct for

Demand Control Ventilation

The DCV CO2 sensor must provide a 2-10 Vdc output. Less
than 1Vdc input assumes a sensor failure and the action of the
outdoor air dampers defaults to < 1Vdc operation in Table 1.
The DCV (CO2) modulates the outdoor damper to provide
ventilation based on occupancy. The DCV setpoint
potentiometer is adjusted to provide ventilation based on the
output of the CO2 sensor. The DCV LED lights when the DCV
(CO2) signal is above setpoint. If the CO2 sensor should fail,
the W7212 will default to the DCV MAX position which is the
minimum position design for 100% occupancy of the space.
M20601
Occupied
Terminal N has
24 VAC power
Yes
No
Yes
b
No
Yes
No
a
<1 Vdc = no CO2 sensor or failed sensor; 1 Vdc = CO2 sen-
sor working but below CO2 set point and CO2 sensor work-
ing and above set point.
b
Economizer should be powered by fan, if fan is off econo-
mizer will spring return damper closed, if fan is on and no
occupancy damper will drive to DCV MAX position.
4
enthalpy sensor in the return air duct.
proper operation.
Table 1. W7212 Terminal Power and Action.
Input on
AQ-AQ1
a
terminals
1 Vdc
1 Vdc
<1 Vdc
<1 Vdc
>DCV set pt
>DCV set pt
Action with 24 VAC
power applied to W7212
(TR-TR1)
Drives to MIN POS
No movement of motor
Drives to MIN POS or
DCV MAX (highest)
Drives to DCV MAX
Drives to up to MIN POS
or DCV MAX (highest)
Drives to DCV MAX