33
Table 11 — EconoMi$er IV Input/Output Logic
*
For single enthalpy control, the module compares outdoor
enthalpy to the ABCD set point.
†
Power at N terminal determines Occupied/Unoccupied setting:
24 vac (Occupied), no power (Unoccupied).
**
Modulation is based on the supply-air sensor signal.
††
Modulation is based on the DCV signal.
*** Modulation is based on the greater of DCV and supply-air sensor
signals, between minimum position and either maximum position
(DCV) or fully open (supply-air signal).
†††
Modulation is based on the greater of DCV and supply-air sensor
signals, between closed and either maximum position (DCV) or
fully open (supply-air signal).
Outdoor Air Temperature (OAT) Sensor
The outdoor air temperature sensor (HH57AC074) is a 10 to
20 mA device used to measure the outdoor-air temperature.
The outdoor-air temperature is used to determine when the
EconoMi$er IV can be used for free cooling. The sensor has 8
selectable temperature changeover setpoints, ranging from
48°F to 78°F. The temperature changeover is set using the 3
dip switches on the sensor See Fig. 58.
Fig. 58 — C7660 Temperature Sensor
Supply Air Temperature (SAT) Sensor
The supply air temperature sensor is a field-installed 3 K thermis
-
tor located on the fan deck. See Fig. 59. This sensor is factory in
-
stalled. The operating range of temperature measurement is 0°F to
158°F (–18°C to 70°C). See Table 12 on page 34 for sensor tem
-
perature/resistance values.
Fig. 59 — Supply Air Sensor Location
The temperature sensor looks like an eyelet terminal with wires
running to it. The sensor is located in the “crimp end” and is
sealed from moisture.
Outdoor Air Lockout Sensor
The EconoMi$er IV is equipped with an ambient temperature
lockout switch located in the outdoor airstream which is used
to lock out the compressors below a 42°F (6°C) ambient tem
-
perature. See Fig. 53 on page 30.
INPUTS
OUTPUTS
Demand
Controlled
Ventilation
(DCV)
Enthalpy*
Y1
Y2
Compressor
N Terminal†
Outdoor
Return
Stage 1
Stage 2
Occupied
Unoccupied
Below set
(DCV LED
Off)
High
(Free Cooling
LED Off)
Low
On
On
On
On
Minimum position
Closed
On
Off
On
Off
Off
Off
Off
Off
Low
(Free Cooling
LED On)
High
On
On
On
Off
Modulating** (between
min. position and full-open)
Modulating** (between
closed and full-open)
On
Off
Off
Off
Off
Off
Off
Off
Minimum position
Closed
Above set
(DCV LED
On)
High
(Free Cooling
LED Off)
Low
On
On
On
On
Modulating†† (between min.
position and DCV maximum)
Modulating†† (between
closed and DCV maximum)
On
Off
On
Off
Off
Off
Off
Off
Low
(Free Cooling
LED On)
High
On
On
On
Off
Modulating***
Modulating†††
On
Off
Off
Off
Off
Off
Off
Off
S
UPPLY AIR
TEMPERATURE
S
EN
S
OR