Aprilaire 75 User manual

Model 75 Dehumidifier Control
Installation Instructions
READ AND SAVE THESE INSTRUCTIONS
CAUTION
1. Read all instructions before beginning installation.
2. Do not use in pool applications. Pool chemicals can damage the control.
3. Do not use solvents or cleaners on or near the display and circuit board.
Chemicals can damage components.
WARNING
1. Improper installation may cause property damage or injury. Installation, service,
and maintenance must be performed by a qualified service technician.
2. 120 Volts may cause serious injury from electric shock. Disconnect electrical
power before starting installation or servicing. Leave power disconnected until
installation/service is completed. This control is not a 120 Volt (line voltage)
device.
SAFETY INSTRUCTIONS
The Model 75 is for use with any dehumidifier requiring a normally
open control, including Aprilaire Models 1710A, 1730A, 1750A, 1770A.
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TABLE OF CONTENTS
Safety Instructions.................. 1
Overview .......................... 2
Specifications...................... 2
Location Recommendations ......... 3
Installation
Mount Control . . . . . . . . . . . . . . . . . . . . . 4
Replacing a Manual Dehumidistat ..... 5
Wiring to 1730A ................... 7
Wiring to 1710A/1750A/1770A ...... 8
System Checkout
Power Up ......................... 9
Test Mode ....................... 10
Humidity Setting .................. 10
Offset ........................... 10
Turning On and Setting Control....... 11
Sequence of Operation ............. 11
Troubleshooting
Error Codes ...................... 11
Troubleshooting Guide.............. 12
OVERVIEW
The Aprilaire®Model 75 Dehumidifier Control provides control of the dehumidifier from the
living space. The control allows the homeowner to set and adjust the humidity setting and turn
dehumidification on or off from a convenient location. The Model 75 uses an onboard sensor
to monitor the relative humidity in the space in which it is located and displays the measured
relative humidity on the digital display.
ELECTRICAL
Input Voltage and Current Voltage: 24V AC +/-20%
Current: 25mA (nominal), 50mA (max.) at 24V AC
Output Dry Contact, Normally Open – DH Terminals
SPECIFICATIONS
CONTROL
Humidity Setting Range 40% – 80% RH
Accuracy +/-5% RH
Differential 3%
Low Limit 40°F Dew Point
High Limit 99°F Dry Bulb
LOCATION RECOMMENDATIONS
MOUNT CONTROL
•Inanareathehomeownerwantsto
monitor and control moisture levels.
•Onaninteriorwall.
•Approximately5’offthefloor.
•Atleast18”fromanoutsidewall.
DO NOT MOUNT CONTROL
• Intheflowofasupplyregister.
•Behinddoors,incornersorotherdeadairspaces.
•Indirectsunlight,nearlightingfixtures,orother
appliances that give off heat.
•Onanoutsideorunconditionedareawall.
•Instairwellsornearoutsidedoors.
•Onawallwithconcealedpipesorductwork.
FIGURE 1 – Mounting Control
90-1640
2
3

INSTALLATION
MOUNT CONTROL
If replacing a control mounted in the living space, see Control Mounted in Living Space on
page 5.
PULL APART
FRONT COVER
BACKING
PLATE
DH
DH
R
C
FIGURE 2 – Disassemble Control
90-1631
DH
DH
R
C
BACKING PLATE
ANCHOR
SCREW
FIGURE 3 – Mount Backing Plate
90-1632
REQUIRED COMPONENTS
18 – 24 gauge wire (field supplied) – 4 wires required, run new cable as needed.
(2)#8x1-1/2”mountingscrews(supplied)
(2) Anchors (supplied)
1.Levelthebackingplateonthewallandmarkthemountingholesandwireaccesslocation
on the wall.
2.Drilltwo3/16”mountingholesanda3/4”wireaccesshole.SeeFigure 3.
3. Install the drywall anchors flush with the wall surface. Note:Mountingholesonthebacking
plate are designed to fit on a horizontal J-box.
4. Run a 4-wire cable from the dehumidifier to the wall mount location and through the square
holeinthebackingplate.
5.Securethebackingplatetothewallusingthetwo#8x1-1/2”screws.
6. Connect wires to the C, R, and both DHterminalsonthebackingplate.
7. Push excess cable into the wire access hole and fill the hole with insulation. Note: Failure
to seal the hole can cause drafts to enter the control and affect sensing accuracy.
REPLACING A MANUAL DEHUMIDISTAT
STEP 1 – REMOVE THE CURRENT MANUAL CONTROL
IF THE CONTROL IS MOUNTED IN THE
LIVING SPACE:
1. Disconnect power to the dehumidifier
and HVAC system.
2.Pullknobfromthedehumidistatcoverand
remove cover from the control base.
3. Remove the four screws from the base plate.
4. Pull the dehumidistat off the wall until wire
nuts are exposed.
5. Remove dehumidistat leads.
6. The existing 2-wire cable can remain. The Model 75 wiring requires 4 wires. Install more
wires as needed.
7. Mount the Model 75 control following steps 1-5 in the MOUNT CONTROL section above.
Reuse the existing wire access hole and wiring as needed.
8. Connect the existing wires (from 1730A REMOTE terminals) to the DH terminals and
connect the remaining two wires to the Cand RterminalsontheModel75backingplate.
9. Proceed to WIRING section on page 7.
FIGURE 4 – Manual Dehumidistat
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5

IF THE CONTROL IS MOUNTED ON A 1730A DEHUMIDIFIER:
1. Disconnect power to the dehumidifier and HVAC system.
2. Pullknobfromthedehumidistatcoverandremovecoverfromthecontrolbase.
3. Remove the four screws from the base plate and pull the dehumidistat off the unit until
4” – 6”ofwireisoutsideoftheunit.
4. Cut the wires and use metal tape to secure the leads to the inside of the unit, preventing
contact with the blower.
5. Removethegasketfromthebaseplate.
6. Installtheinsulatedcoverplate(ServicePart4927)andgasketovertheopening,usingthe
screws removed in step 3. See Figure 5.
7. Remove the wiring access panel on the outlet panel. See Figure 6.
8. Unplug the REMOTE terminals from the circuit board, remove the two wires and cut off the
bare leads. Once cut, the wires may remain in the unit.
9. Replace REMOTE terminals on circuit board and leave wiring access panel off for Model 75
wiring.
10. Proceed to WIRING section on page 7.
COVER PLATE
SERVICE PART 4927
FIGURE 5 – Inlet with Cover Plate
90-1642
WIRING ACCESS PANEL
FIGURE 6 – Wiring Access Panel
on Outlet
90-1633
WIRING
STEP 2 – SUPPLY 24VAC TO THE MODEL 75 CONTROL
The Model 75 control requires 24VAC. Pulling power from the HVAC system is the
recommended method.
MODEL 75 TO 1730A
1. Disconnect power to the dehumidifier and HVAC system.
2. If replacing a dehumidistat that was in the living space, follow steps 3-6. If replacing a
dehumidistat that was on the dehumidifier, follow steps 7-13.
3. Connect the wires from the Cand Rterminals on the Model 75 to the HVAC or thermostat
Cand Rterminals.
4. Connect the existing wires connected to the REMOTE terminals to the DH terminals on
the Model 75.
5. SnaptheModel75frontcoveronthebackplate.The4-pinterminalalignswiththe
terminalblockreceptacleonthebackplate.
6. Proceed to SYSTEM CHECKOUT on page 9.
7. Remove the wiring access panel (if not already removed) on the dehumidifier outlet panel.
8. Unplug the REMOTE terminals from the circuit board.
9. Connect the wires from the DH terminals on the Model 75 to the REMOTE terminals and
plugtheterminalsbackintotheunitcircuitboard.
10. Connect the wires from the Cand Rterminals on the Model 75 to the HVAC or thermostat
Cand Rterminals.
11. Replace the wiring access panel on the dehumidifier.
12. SnaptheModel75frontcoveronthebackingplate.The4-pinterminalalignswiththe
terminalblockreceptacleonthebackingplate.
13. Proceed to SYSTEM CHECKOUT on page 9.
DH
DH
R
C
FLOAT
SWITCH
REMOTE
G-STAT
R-HVAC
G-HVAC
R
C
G
W
Y
HVAC
EQUIPMENT
R
C
G
W
Y
THERMOSTAT
EXISTING WIRING
ADDITIONAL MODEL 75 WIRING
FIGURE 7 – Model 75 to 1730A Wired to HVAC System
90-1641
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MODEL 75 TO 1710A /1750A /1770A
1. Disconnect power to the dehumidifier and HVAC system.
2. Remove the control door on the dehumidifier inlet panel.
3. Connect one wire from the DH terminal on the Model 75 to the DH terminal on the control
board.
4. Connect the other wire from the DH terminal on the Model 75 to the Rf terminal on the
control board.
5. Connect the wires from the Cand Rterminals on the Model 75 to the HVAC or thermostat C
and Rterminals.
6. Set SYSTEM SETUP switches to EXTERNAL and WHL HOUSE. See Figure 9.
7. Replace the control door on the dehumidifier.
8. SnaptheModel75frontcoveronthebackingplate.The4-pinterminalalignswiththe
terminalblockreceptacleonthebackingplate.
MODEL
75
DH
R
DH
C
DAMPERS
Rf DH -WGhGs
Cf
VENT
HVAC EQUIP REMOTE
DEH B +A
DEHUMIDIFIER
CONTROL BOARD
HVAC EQUIPMENTTHERMOSTAT
G
R
C
G
W
YY
W
C
R
SENSOR
ODT
FLOAT
SWITCH
EXISTING WIRING
ADDITIONAL MODEL 75 WIRING
FIGURE 8 – Model 75 to 1710A/1750A/1770A
Wired to HVAC System
90-1537
4321
ON
HVAC FAN OFF
WHL HOUSE
VENT-AUTO VENT- TIMED
HVAC FAN ON
SYSTEM SETUP
EXTERNAL
CONVERTIBLE
LOCAL
FIGURE 9 – Dip Switch
Configuration
90-1538
Wiring Note: The dehumidifier Rf
and Cf terminals must be powered
from the transformer that powers
the Model 75 Control.
SYSTEM CHECKOUT
POWER UP
1.Checkallwiring.
2. Plug in dehumidifier and restore power to the HVAC system.
3. Turn on/off switch on dehumidifier ON. After a 4 second start up sequence all buttons on
the Model 75 will be functional.
 •ThecontrolwillbeOFF.
 •Thehumiditysettingwillbe60%.
 •Thecontrolwilldisplaythemeasuredhumidity.
FIGURE 10
90-1636
Model 75 Control
Model 75 LCD Display
Blinking ON +*: Control Limit Exceeded.
See Control Limits, page 11.
Solid ON:
Control On
Blinking ON:
Dehumidifying
Measured
Humidity or
Setting
Control On/Off
Humidity Setting
and Offset
Adjustment
Control must be
ON to adjust offset
and setting.
SET: Shows when
humidity setting
displayed or being
changed.
OFF: Control Off
System Setup Note:
The convertible configuration is not
available with the Model 75 control.
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9

TEST MODE
1. Press and hold the ON button for 5 seconds to enter Test Mode.
 a.VerifyallLCDsegmentsblinkeverysecond.
b. Verify dehumidifier turns on.
2. After 5 minutes or after pressing the OFF button, the control will enter Off mode.
a. Verify the dehumidifier turns off.
HUMIDITY SETTING
•ThecontrolmustbeONtoadjustthehumiditysetting.
•The (up) and (down) buttons are used to increase or decrease the humidity setting.
•ThefirstpressofeitherbuttonwilldisplaythecurrentsettingontheLCDdisplayandSET
will be displayed below the % sign.
•Eachsubsequentpushoftheupordownbuttonswillchangethesettingby1%.
•Ifabuttonishelddown,thesettingwillcontinuallychangeby1%every1/2secondforas
long as the button is pressed.
•ThecontrolwillreturntoNormalMode,displayingthemeasuredhumidity,5secondsafter
the last button press/release.
OFFSET
An offset can be applied to the humidity reading to
avoid discrepancies with other humidity measuring
devices in the home. Allow 48 hours for the control to
acclimate before applying an offset. The control must
be ON to enter the Offset screen.
•PressandholdtheOFFbuttonfor5secondsto
enter the Offset screen.
•The buttons can be used to set an offset
value between -5% RH and +5% RH.
•ThecontrolwillreturntoNormalMode,displaying
the measured humidity, 5 seconds after the last
button press/release.
TURNING ON AND SETTING CONTROL
1. Press the ON button.
2. Use the buttons to set the control at 59%.
Increasing the humidity setting will decrease dehumidifier run time, allowing for higher
humidity levels.
Decreasing the humidity setting will increase dehumidifier run time, allowing for lower
humidity levels.
FIGURE 11 – Offset Screen
90-1638
SEQUENCE OF OPERATION
Normal Mode
•Whenthemeasuredhumidityisgreaterthanthesetting,thecontrolwillactivatethe
dehumidifieroutput,thedehumidifierwillbegindehumidifyingandONwillblinkonthe
LCD display.
•Whenthemeasuredhumidityfalls3%belowthesetting,thecontrolwilldeactivatethe
dehumidifier output, the dehumidifier will stop dehumidifying and the LCD will display a
solid ON.
Control Limits
•Ifthecontrolmeasuresadewpointbelow40°FORatemperatureabove99°F,thecontrol
will deactivate the dehumidifier output if actively dehumidifying, the dehumidifier will stop
dehumidifying, and ON and *willblinkontheLCDscreen.
•Thecontrolwillresumenormaloperationwhenthemeasureddewpointisgreaterthan45°F
or the measured temperature is below 94°F, whichever control limit was exceeded.
Technical Support is available Monday through Friday, 7:00 a.m. to 5:00 p.m. CST, at
[phone]. Use the guide on the following page to help find and correct system faults.
Contact Technical Support before replacing the control or for additional troubleshooting.
TROUBLESHOOTING
When the control detects an internal error, it
will stop controlling, deactivate the dehumidifier
output, and the LCD will display the Error Code.
See Figure 12. The control will attempt to
recover from the error every 10 minutes. The Error
Code will continue to be displayed as long as
the error condition exists. Button presses are not
registered when in Error Mode. Cycling power to
the control will not clear the code and the control
will need to be replaced.
ERROR CODES
FIGURE 12 – Error Code Screen
90-1645
10
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TABLE 1 – Troubleshooting Guide
Symptom Possible Reason Troubleshooting Procedure
No power to the
control.
Incorrect wiring. Verify wiring connections between control,
dehumidifier and HVAC system (where applicable).
No power to dehumidifier. •VerifythatthedehumidifierpowerswitchisON.
•Verifythecircuitbreakerhasnottripped.
No power to HVAC
equipment.
•VerifyHVACsystemswitchison.
•Verifythecircuitbreakerhasnottripped.
Control does
not turn on
dehumidifier
output.
Incorrect wiring. Verify wiring connections between control and
dehumidifier.
Control does not
turn on HVAC fan.
Incorrect wiring. Verify wiring connections between dehumidifier
and HVAC system.
Display does
not flash all LCD
segments during
Test Mode.
LCD error. Replace control.
Display shows
EE.
Control detected an
internal error.
The control will need to be replaced.
Inaccurate
humidity reading.
Control recently installed
after being stored in an
uncontrolled temperature
and humidity environment.
Allow 48 hours for control to acclimate.
Offset has been applied to
the humidity reading.
Change the offset.
Control is mounted in direct
sunlight, above a heat or
humidity source, or in the
path of a supply register.
Relocate the control.
P.O.Box1467•Madison,WI53701-1467•Phone:800/334-6011 •Fax:608/257-4357
www.aprilairepartners.com
10009383 4.11
B2205372A
Printed in U.S.A.
© 2011 Aprilaire – A division of Research Products Corporation
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