Aprilaire 1750A - External Control

MODEL 76 EXTERNAL CONTROL
WIRING & DIP SWITCH CONFIGURATION
When used as an external control, the Model 76 acts like a dehumidistat and will turn the dehumidifier on and off when the relative humidity
goes above or below the setting. The Model 76 must be installed in the space that is being served by the dehumidifier. One example of
this would be to install the Model 76 in the home’s living space and wire it to the dehumidifier which is located in the basement and is ducted
to the HVAC system. The Model 76 will override the dehumidifier control sensors and on-board control knob setting. Refer to the Model 76
Installation Instructions for location, mounting, and operating instructions. The dehumidifier control knob can only be used to initiate Test Mode
when a Model 76 is connected.
FIGURE 27 – Model 76 External Control
DIP Switch Configuration
90-1538
LOCAL
PRIMARY/SECONDARY
EXTERNAL
SYSTEM SETUP
HVAC FAN ON
VENT-TIMED
VENT-AUTO
PRIMARY
HVAC FAN OFF
ON
1234
MODEL
76
DAMPERS
Rf DH -WGhGs
Cf
VENT
HVAC EQUI
PR
EMOTE
DE
HB
+A
DEHUMIDIFIER
CONTROL BOARD
HVAC EQUIPMENTTHERMOSTAT
G
R
C
G
W
YY
W
C
R
SENSOR
ODT
FLOAT
SWITCH
EXISTING WIRING
ADDITIONAL MODEL 76 WIRING
R/+
B
C/
-
A
DH
DH
90-1537
SEQUENCE OF OPERATION
Whole-Home
•WhenthemeasuredhumidityisgreaterthanthehumiditysettingontheModel76,ON blinks on the LCD display, the dehumidifier damper
output turns on, the dehumidifier blower turns on, and the green Status LED on the dehumidifier flashes.
•Threesecondsafterthedehumidifierblowerturnson,thecompressorturnsonandthegreenStatusLEDswitchestosolidillumination.
•Whenthemeasuredhumidityfalls3%belowthesettingontheModel76,theLCDdisplaysasolidON, the dehumidifier damper output turns
off and the dehumidifier compressor and blower turn off along with the green Status LED.
FIGURE 26 – Model 76 External Control Wiring
Wiring Note: The dehumidifier Rf
and Cf terminals must be powered
from the transformer that powers
the Model 76 Control.
19