Aprilaire Model 8120X Digital Ventilation Controller

Product Overview

The Aprilaire Model 8120X Digital Ventilation Controller is designed to manage whole-house ventilation, ensuring optimal indoor air quality by controlling the intake of fresh outdoor air. This manual provides comprehensive guidance for installation, setup, operation, and troubleshooting.

Image Description: The controller features a digital display showing ventilation settings, a 'CODE' indicator, 'MIN/HR' units, a 'Select' button, and a 'Fresh Air' indicator. The Aprilaire logo is present.

Important Instruction: READ AND SAVE THESE INSTRUCTIONS.

Table of Contents

• Warnings and Cautions
• Package Contents
• Specifications
• Mounting the Controller and Outdoor Temperature Sensor
• Wiring
• Operation
• Set Up Menu
• Test Mode
• Rater/Inspector Verification
• Sequence of Operation – "Code" Setting
• Sequence of Operation – “Comfort” Setting
• Limited Warranty

Warnings and Cautions

⚠️ WARNING

• 120 volts can cause serious injury from electric shock. Disconnect electrical power to the HVAC system before proceeding.
• Sharp metal edges can cause serious injury from cuts. Use gloves when cutting openings in sheet metal.

ℹ️ NOTICE

• When installing the Ventilation Controller on downflow furnaces, ensure that the furnace blower continues to run sufficiently long after the heat call is satisfied to prevent temperatures from exceeding the maximum operating temperature.
• Do not mount the Ventilation Controller downstream from any fresh air intake port, humidifier bypass or zone control bypass. False humidity conditions will cause the Ventilation Controller to operate incorrectly.

Package Contents

• CONTROL unit
• WALL PLATE
• #8 x 5/8" HEX HEAD SHEET METAL SCREW (2)
• #8 x 1/2" PAN HEAD TYPE 25 SCREW (2)
• DUCT BOARD BRACKET
• INSTALLATION MANUAL
• OUTDOOR TEMP SENSOR

Specifications

Mounting the Controller and Outdoor Temperature Sensor

Mounting to an 8140NC Ventilator

Note: In hot/humid climates where limiting ventilation with high indoor RH is important, mount the control to the return duct and mount the outdoor temperature sensor as shown on pages 6-9. If humidity limits are not used, the control can be mounted to the housing of the Model 8140NC, and the outdoor temperature sensor does not need to be installed.

1. Remove the wall plate from the control and set the control aside in a safe location until wiring is completed.
2. Remove the sensor hole plug from the cover of the Model 8140NC.
3. Use the supplied #8 x 1/2" hex head sheet metal screws to mount the wall plate to the cover of the Model 8140NC.

Diagram Description: Shows the wall plate being attached to the Model 8140NC ventilator cover using screws, with a sensor hole indicated.

Mounting the Controller to the Return Ductwork

Note: Mount the controller to the return ductwork at a location where the temperature and humidity in the duct are most representative of the home. Keep the controller at least 6 inches upstream from the point where the fresh air duct enters the return duct, and 6 inches upstream from a humidifier outlet.

Sheet Metal Installation

1. Remove the wall plate from the control and set the control aside in a safe location until wiring is completed.
2. Mark the location of the wall plate sensor hole on the duct. Use a step-drill bit to create a 5/8" (0.625") hole for the sensor.
3. Center the sensor hole in the wall plate over the hole in the duct, level the wall plate, and mark the locations of the two mounting slots. Drill small pilot holes using a #36 (0.106") or smaller drill bit at the two mounting locations.
4. Use the supplied #8 standard hex head sheet metal screws to mount the wall plate to the duct.

Diagram Description: Illustrates mounting the wall plate to a sheet metal return duct. It shows the 5/8" sensor hole, pilot holes for screws, and the wall plate positioned on the duct.

Duct Board Installation

1. Take out the duct board mounting bracket, remove the wall plate from the control, and set the control aside in a safe location until wiring is completed.
2. Cut a 5.75" x 5.25" rectangular opening in the return plenum. Save the piece cut out to insulate the duct board bracket around the controller. The display of the control should run parallel with the long dimension. DO NOT MOUNT THE CONTROL IN A POSITION WHERE IT IS FACING DOWN.
3. Use the supplied #8 x 1/2" type 25 pan head screws to mount the control wall plate to the duct board mounting bracket.
4. Place the bracket in the cut out and seal in place using metal foil tape and/or mastic.
5. Insulate the duct board bracket around the wall plate using the plug cut out of the duct board.

Diagram Description: Shows the duct board mounting bracket being installed into a return plenum. It details cutting the opening, attaching the wall plate to the bracket, sealing with tape, and using insulation.

Mounting the Controller in a Closet Return Plenum

Note: Do not mount directly in the path of the outdoor air. Mount the control where it will sense the relative humidity of the return air.

1. Remove the wall plate from the control and set the control aside in a safe location until wiring is complete.
2. Use spacers or brackets to mount the controller to an inside wall surface or return plenum/duct surface that is at room temperature (i.e., do not mount to supply ductwork or to the air handler/furnace) to space the wall bracket a minimum of 1/2 inch away from the surface.
3. Mount the wall bracket to the surface using #8 screws (field supplied – do not use flat head screws) and wall anchors (field supplied) if mounting to drywall. Ensure that there is room for air to flow behind the wall bracket. DO NOT install screws in the wall bracket anywhere except intended mounting holes.

Diagram Description: Illustrates mounting the wall plate in a closet return plenum using spacers and #8 screws, ensuring a 1/2 inch gap for airflow.

Mounting the Outdoor Temperature Sensor

This sensor should be installed in the fresh air inlet hood.

1. Drill a 3/8" diameter hole in the duct of the fresh air inlet hood.
2. Install the outdoor temperature sensor into the duct and use metal foil tape to secure it in place and seal the opening. Run the wire toward the outside wall.
3. Secure ductwork to the inlet hood duct while allowing the wire of the sensor to extend outside of the insulation. Tape and/or mastic the duct as needed and properly insulate.

Diagram Description: Shows a three-step process for installing the outdoor temperature sensor: 1. Drilling a 3/8" hole in the fresh air inlet hood. 2. Installing the sensor and securing it with foil tape. 3. Running the wire and ensuring proper sealing and insulation of the ductwork.

Wiring

Important: Disconnect power to the HVAC system to prevent electrical shorts while wiring.

1. Run a 2-conductor cable from the control to the outdoor temperature sensor (if installed) and wire to the controller ODT terminals.
2. Run an 8-conductor thermostat cable from the control to the HVAC equipment. Wire the controller to the HVAC equipment in accordance with the diagrams below. Contact customer service if wiring assistance is needed for other equipment configurations.
3. Run a 2-conductor cable from the control to either the damper in Model 8126X installations or to the Model 8140NC Fresh Air Ventilator and wire according to the relevant figure.

Wiring to Furnace (Figure 1)

Thermostat Connections: R, C, Y, W, O, GS, GH

Controller Connections: R, C, Y, W, O, GS, GH, ODT, VENT

Terminal Definitions:

• R & C = 24 VAC
• Y = COOLING
• W = HEAT
• GS = FAN INPUT
• GH = FAN OUTPUT

Diagram Description: Shows wiring from a thermostat to the Model 8120X Digital Ventilation Control and to a furnace, including connections for R, C, Y, W, O, GS, GH, and ODT (Outdoor Temperature Sensor).

Wiring to Heat Pump (Figure 2)

Heat Pump Thermostat Connections: R, C, Y, W1, O, G

Controller Connections: R, C, Y, W1, O, G, ODT, VENT

Terminal Definitions:

• R & C = 24 VAC
• Y = COMPRESSOR
• W1 = 1st STAGE AUX. HEAT
• O = REV. VALVE, COOLING
• GS = FAN INPUT
• GH = FAN OUTPUT

Diagram Description: Illustrates wiring from a heat pump thermostat to the Model 8120X Digital Ventilation Control and to a heat pump, including connections for R, C, Y, W1, O, G, GS, GH, and ODT.

Wiring to Model 8140NC Fresh Air Ventilator (Figure 3)

Connect the VENT terminals on the controller to the VENT terminals on the Model 8140NC Ventilator.

Diagram Description: A simple diagram showing a direct connection between the VENT terminals of the Model 8120X controller and the Model 8140NC Ventilator.

Wiring to Model 6506 Damper (Figure 4)

This wiring configuration typically involves a 24 VAC, 10VA transformer (provided with Model 8126X) and the Model 6506 Damper.

Diagram Description: Depicts wiring for a Model 6506 Damper, showing connections from a 24 VAC transformer and the VENT terminals of the Model 8120X controller to the damper.

After routing wires into the channels in the back of the control, snap the control onto the wall plate. Restore power to the HVAC system.

Operation

The controller display appears faint normally; the first press of any button turns it on at full power.

The display shows the ventilation time setting (minutes/hr), the mode of operation (Code or Comfort), and whether the HVAC fan has been turned on when ventilating.

Controls:

• Select Button: Used for Rater/Inspector Verification. Press and hold for 5 seconds to enter Test Mode or Set Up Menu.
• Fresh Air Button: Use to override the calculated ventilation time setting (6 – 60 minutes/hr). Press and hold to turn ventilation OFF. To return to the calculated setting, go completely through the Set Up Menu.

The green Fresh Air LED lights up when ventilating.

Set Up Menu

ℹ️ NOTICE: Before setting up the control for use, the amount of ventilation air being delivered (CFM) by the installed ventilation system must be measured.

Procedure:

1. Press and hold the Select button for 5 seconds, then release.
2. Use the ▲ and ▼ buttons to change values. Use the Select button to enter the value and move to the next Set Up Menu item.

Menu Items:

When all Set Up Menu options have been entered, the control will display "donE".

Test Mode

After wiring and set up have been completed, Test Mode can be used to verify that all components in the ventilation system function and that wiring to the HVAC system fan is correct.

Procedure:

1. Press and hold the Select button for 5 seconds.
2. Use the ▲ and ▼ buttons to navigate.
3. Press Select to start the test sequence.

Test Sequence:

After 45 seconds, Test Mode automatically completes, and the display returns to the operating display.

Rater/Inspector Verification

To verify the ventilation time setting, press the Select button to scroll through the calculated Required Continuous CFM and the Measured CFM for this installation. If any value does not match the expected value, the Set Up Menu must be entered to change the floor area, number of bedrooms, or measured CFM.

Minutes per Hour = 60 * (Required Continuous CFM / Measured CFM)

Measured CFM is entered during set up, and Required Continuous CFM is calculated according to the equation below:

Required Continuous CFM = ((Floor Area ft² * .01) + (No. of Bedrooms + 1) * 7.5)

Sequence of Operation – "Code" Setting

The control will turn on ventilation with a heating, cooling, or fan call for the set number of minutes during a one-hour cycle period. If the outdoor temperature is above the high temperature ventilation limit, ventilation will not occur with a cool or fan call, but if it is below the low temperature ventilation limit, it will occur with a heat call. If the HVAC equipment does not turn on enough to meet the ventilation time within the hour, the control will turn on ventilation without a call, if the outdoor air temperature is within the high and low ventilation temperature limits. The control will also turn on the HVAC system blower, if wired and set up to do so.

If the outdoor temperature exceeds the limits set at the end of the first hour, then no additional ventilation will occur for another 60 minutes, and the cycle period will automatically adjust to four hours. When the ventilator starts again, it will sample the air temperature and if in range, will meet the set amount of ventilation during the four-hour cycle period. For example, if the Vent Time was set to 25 minutes per hour and the air temperature fell below the low limit setting, ventilation would only occur during a heating call. If the heating only operated for 10 minutes during the hour, the control will automatically change the cycle period to four hours and work to provide the additional 90 total minutes of ventilation (25 min/hr * 4 hours = 100 minutes, minus the 10 minutes of ventilation that occurred during heating) during the four-hour cycle period.

If the air temperature is still out of range, the control will automatically switch to an 8-hour cycle period, then a 12-hour cycle period, and finally a 24-hour cycle period. During 8, 12, and 24-hour cycle periods, the total ventilation time increases to compensate for ventilation effectiveness as defined in ASHRAE Standard 62.2-2010. When the cycle period automatically adjusts to 24-hours, the control will turn on ventilation to meet the requirements even if the temperature is outside of the set limits.

Sequence of Operation – "Comfort" Setting

The control will turn on ventilation with a heating, cooling, or fan call by the HVAC equipment, if the outdoor air temperature is within the high and low ventilation temperature limits and the indoor RH is within the high and low RH limits, for the set number of minutes during a one-hour cycle period. If the HVAC equipment does not turn on enough to meet the ventilation time within the hour, the control will turn on ventilation without a call, if the outdoor air temperature and indoor RH are within the set limits. The control will also turn on the HVAC system blower, if wired and set up to do so. If the outdoor temperature or indoor RH are outside of the set limits, then no ventilation will occur.

Limited Warranty

Your Research Products Corporation Aprilaire® Digital Ventilation Controller is expressly warranted for five (5) years from date of installation to be free from defects in materials or workmanship. Research Products Corporation's exclusive obligation under this warranty shall be to supply, without charge, a replacement for the Controller which is found to be defective within such five (5) year period and which is returned not later than thirty (30) days after said five (5) year period by you to either your original supplier or to Research Products Corporation, Madison, Wisconsin 53701, together with the installation date of the controller.

THIS WARRANTY SHALL NOT OBLIGATE RESEARCH PRODUCTS CORPORATION FOR ANY LABOR COSTS AND SHALL NOT APPLY TO DEFECTS IN WORKMANSHIP OR MATERIALS FURNISHED BY YOUR INSTALLER AS CONTRASTED TO DEFECTS IN THE CONTROLLER ITSELF.

IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE SHALL BE LIMITED IN DURATION TO THE AFORESAID FIVE YEAR PERIOD. RESEARCH PRODUCTS CORPORATION'S LIABILITY FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES, OTHER THAN DAMAGES FOR PERSONAL INJURIES, RESULTING FROM ANY BREACH OF THE AFORESAID IMPLIED WARRANTIES OR THE ABOVE LIMITED WARRANTY IS EXPRESSLY EXCLUDED. THIS LIMITED WARRANTY IS VOID IF DEFECT(S) RESULT FROM FAILURE TO HAVE THIS UNIT INSTALLED BY A QUALIFIED HEATING AND AIR CONDITIONING CONTRACTOR. IF THE LIMITED WARRANTY IS VOID DUE TO FAILURE TO USE A QUALIFIED CONTRACTOR, ALL DISCLAIMERS OF IMPLIED WARRANTIES SHALL BE EFFECTIVE UPON INSTALLATION.

Some states do not allow limitations on how long an implied warranty lasts or the exclusion or limitation of incidental or consequential damages so the above exclusion or limitations may not apply to you.

This warranty gives you specific legal rights and you may also have other rights which vary from state to state.

Warranty Registration

Visit us online at www.aprilaire.com to register your Aprilaire product. If you do not have online access, please mail a postcard with your name, address, phone number, email address, product purchased, model number, date of purchase, and dealer name and address to: Research Products Corporation, P.O. Box 1467, Madison, WI 53701.

Your warranty registration information will not be sold or shared outside of this company.

AprilairePartners.com
P.O. Box 1467
Madison, WI 53701-1467
800.334.6011 F: 608.257.4357

Printed in USA

©2018 Aprilaire – Division of Research Products Corporation

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