Safety Instructions
[DANGER] ATTENTION INSTALLER: To prevent serious injury from electrical shock this product must be installed by a qualified HVAC contractor. 120 volts can cause serious injury from electric shock. Disconnect electrical power to the HVAC system before proceeding.
[CAUTION] Do not mount the Ventilation Controller on the supply plenum or duct. The unit can lose its calibration when exposed to elevated temperatures. When installing the Ventilation Controller on downflow furnaces, ensure that the blower continues to run after the heat call is satisfied to prevent high temperatures from damaging the Control circuit board. Do not mount the Ventilation Controller downstream from any fresh air intake port, humidifier or bypass outlet. False humidity conditions will cause the Ventilation Controller to operate incorrectly.
[WARNING] Sharp metal edges can cause serious injury from cuts. Use gloves when cutting plenum openings and handling ductwork.
Specifications
| Specification | Value |
|---|---|
| Operating temperature range | 20-160°F |
| Maximum current through VENT relay | 2A |
| Input voltage | 22-30 VAC |
| Minimum VA required | 2.0 VA |
Overview
The ventilation controller brings in fresh air and activates the HVAC fan to cycle the fresh air throughout the home. The controller is designed to meet the ASHRAE 62.2-2010 standard for ventilation. The ventilation mode selection allows for time-only operation or for temperature and humidity limits to be applied to the incoming air.
Mounting Location
The controller must be installed in the return duct, at least 6 inches upstream of the fresh air intake opening, the humidifier if present, and/or the humidifier bypass duct opening (see Figures 1 & 2).
Figure 1 - Typical Attic Installation
Diagram shows a typical attic installation. Components include: FRESH AIR INTAKE HOOD W/SCREEN, MOTORIZED DAMPER, FRESH AIR INTAKE DUCT, FILTER, FURNACE/AIR HANDLER, SUPPLY PLENUM, and VENTILATION CONTROLLER. The controller is positioned in the return duct, 6 inches upstream of the fresh air intake duct. Airflow is indicated from fresh air, through the intake duct, damper, filter, furnace/air handler, to the supply plenum. The diagram also shows a gable end wall, band joist, or porch soffit as the mounting structure.
Figure 2 - Typical Basement Installation
Diagram shows a typical basement installation. Components include: FRESH AIR INTAKE HOOD W/SCREEN, FRESH AIR INTAKE DUCT, MOTORIZED DAMPER, VENTILATION CONTROLLER, HUMIDIFIER, FILTER, FURNACE/AIR HANDLER, RETURN DUCT, and SUPPLY DUCT. The controller is positioned in the return duct, 6 inches upstream of the fresh air intake duct and humidifier. Airflow is indicated from the outside wall, through the intake duct, damper, filter, furnace/air handler, to the supply duct. The return duct is shown leading to the furnace/air handler.
Mounting Controller
Disassemble the Controller
Remove the knob. Remove the cover by pulling at the bottom and swinging out and up.
Mount Controller to Duct
After the location of the controller is selected, drill a 3/4 inch hole for the RH sensor (the RH sensor extends from the back of the controller). Before removing the adhesive backing, use the controller to mark the mounting holes and place anchors if applicable. Clean the mounting surface of the duct, remove the adhesive backing from the gasket on the controller, and secure the controller to the duct making sure to align mounting holes and the RH sensor with the drilled hole.
Mounting to Metal Duct: Use field supplied sheet metal screws to secure controller to duct.
Mounting to Duct Board: Use field supplied screws and anchors to secure controller to duct.
Make sure the controller sensor gasket is sealed tightly around the drilled hole. Do not install the controller without the gasket.
Figure 3 - Fiber and Sheet Metal Duct Mount
Diagram shows the controller and its cover. A 3/4 inch diameter hole is indicated for sensor mounting. The controller is shown with its gasket. Note: When replacing an older controller, the duct opening must be completely covered. Locate and install the new controller as instructed above.
Ductwork & Damper Installation
[CAUTION] 1. Sharp edges may cause serious injury from cuts. Use care when cutting openings and handling duct work. 2. Install damper in fresh air duct as close to the return duct as possible. 3. Do not force damper blades by hand, as damage may occur.
Ductwork Specifications
- Insulated duct of at least R-4 insulating value with a continuous vapor barrier must be used for the intake duct. The vapor barrier must be seated at both ends.
- All flexible ducts must meet UL safety standards for Class I air ducts and connectors.
- All ducting must be installed according to HVAC codes and standards.
- For optimum performance, keep duct run as short and straight as possible.
- All duct connections should be sealed with UL181 foil tape or mastic to prevent leakage.
- Exterior intake hood must be weather resistant.
- Exterior intake hood must have a screen (1/4" openings) to prevent unwanted debris, animals, and insects from entering ductwork. A metal open hood model is recommended. An intake vent with plastic louvers significantly reduces airflow.
- Exterior intake hood should be above the expected snow line or a minimum of 18" above ground level, whichever is greater.
- Exterior intake hood should be a minimum of 10 ft. from appliance vents or other sources of pollution and/or extreme temperatures, such as furnace exhaust or car exhaust, etc.
Damper Installation
- Install damper with crimped end downstream.
- Slide damper over end of crimped duct and secure to duct with 1/2 inch long sheet metal screws (not included).
- Insulate the damper assembly. Leave the motor cover exposed for wiring.
NOTE: Support all duct work in accordance with local code or SMACNA standards.
NOTE: The damper blade, as supplied, is fully closed when not powered and will fully open when powered. The stop screw can be used to limit how much the damper opens when powered. The damper is 10 VA at 24 VAC power-opened/spring-closed.
Figure 4 - Aprilaire Damper
Diagram of the Aprilaire Damper, showing components: BRACKET, MOTOR, INDICATOR LABEL, and ADJUSTABLE STOP SCREW. The damper is shown with its plastic cover removed.
Figure 5 - Damper Installation
Diagram illustrating damper installation into a round duct. Components shown: FRESH AIR INTAKE, ROUND DAMPER, AIR FLOW DIRECTION. An instruction indicates 'DO NOT INSULATE ACTUATOR'.
Wiring
Disconnect power to HVAC equipment. Make wire connections as shown in Figure 6.
- Wire the 24VAC transformer (provided with Model 8126A only). The transformer should be continuously energized; do not wire to the HVAC blower circuit. The transformer, damper, and the ventilation controller “VENT” terminals will be wired in series.
- Wire R, C, and W terminals on the ventilation controller to the corresponding terminals on the HVAC control board. Leave any existing R, C, and W leads in place.
- Disconnect the thermostat wire from the HVAC terminal G and connect it to the ventilation controller G terminal.
- Wire Gf on the ventilation controller to the HVAC terminal G. The only wire connected to HVAC G will be from the ventilation controller Gf terminal.
Figure 6 - Wiring to Controller
Diagram shows the 8120A DIGITAL VENTILATION CONTROLLER TERMINAL STRIP with POWER (R, C, RC, USED) and INPUTS/OUTPUTS (ODT, W, G, VENT, Gf) terminals. It illustrates connections to a THERMOSTAT (R, C, G, Y, W), FURNACE (R, C, G, Y, W), and a DAMPER. A CONTINUOUSLY POWERED 24 VAC TRANSFORMER is also shown, wired to the damper and the controller's VENT terminal.
Outdoor Temperature Sensor (ODT)
If selecting a mode with temperature limits (B, C or D), the outdoor temperature sensor must be installed.
Select Mounting Location for Outdoor Temperature Sensor (ODT)
The temperature sensor can be located in the fresh air duct, in the vent inlet, or on the outside of an exterior wall.
- Do not mount in direct sunlight.
- Do not mount closer than three feet to any exhaust vent.
- Do not route wire alongside 120VAC wires.
- Do not use more than 300 feet of wire to connect the sensor.
- Do not mount below the expected snow line on exterior walls.
Figure 7 - ODT Mounted Outside
Diagram shows the outdoor temperature sensor mounted on the exterior of a home, on the NORTH, EAST, OR WEST SIDE. It is positioned above the expected snow line and away from exhaust vents. Components: OUTDOOR TEMPERATURE SENSOR, SENSOR BRACKET, OUTDOOR TEMPERATURE SENSOR LEADS.
Figure 8 - ODT Mounted in Intake Duct
Diagram shows the outdoor temperature sensor mounted inside the fresh air intake duct. It is positioned on the CENTER LINE, with a maximum distance of 36 inches from the outside wall.
Mode Selection
This controller is equipped with 4 mode settings. The “A” mode allows the controller to ventilate based on time only. The “B”, “C”, and “D” modes allow the controller to ventilate based upon time, outdoor temp, and indoor humidity.
Mode A (Time Only)
Timer controlled ventilation (No temperature or humidity limits). This setting can be calculated with ASHRAE 62.2-2010 standards. (Temperature and humidity sensors are ignored.)
Mode B (Default)
Timer controlled ventilation with humidity and temperature limits.
Chart for Mode B
Chart showing VENTILATION ALLOWED vs. VENTILATION PREVENTED based on OUTDOOR TEMPERATURE (F) and INDOOR RELATIVE HUMIDITY. It includes a region for VENTILATION ALLOWED WITH HEAT.
Mode C (Cold Climate)
Timer controlled ventilation with humidity and temperature limits.
Chart for Mode C
Chart showing VENTILATION ALLOWED vs. VENTILATION PREVENTED based on OUTDOOR TEMPERATURE (F) and INDOOR RELATIVE HUMIDITY. It includes a region for VENTILATION ALLOWED WITH HEAT.
Mode D (Warm Climate)
Timer controlled ventilation with humidity and temperature limits.
Chart for Mode D
Chart showing VENTILATION ALLOWED vs. VENTILATION PREVENTED based on OUTDOOR TEMPERATURE (F) and INDOOR RELATIVE HUMIDITY. It includes a region for VENTILATION ALLOWED WITH HEAT.
Determine Ventilation Requirements
Calculate Ventilation Time Requirements and Select Ventilation Time Setting
Step 1. Determine the minimum ventilation requirement.
This is calculated using ASHRAE 62.2-2010. Airflow in CFM = [House Area in Sq Ft x 0.01] + [No. bedrooms +1 x 7.5]. Use the Number of Bedrooms (Plus 1) or the Number of Occupants, whichever is larger. Additional ventilation may be required for pets, hobbies, fireplaces and attached garage, etc. If more outdoor air is required than the Ventilation Controller can deliver, increase delivered CFM by: reducing bends in duct, increasing duct size, adding a second duct, or adding a powered fan.
Indicate the required CFM: __________
| Home Size (ft²) | Number of Bedrooms | ||||
|---|---|---|---|---|---|
| < 2 | 2 - 3 | 4 - 5 | 6 - 7 | > 7 | |
| ≤ 1500 | 30 | 45 | 60 | 75 | 90 |
| 1501 - 3000 | 45 | 60 | 75 | 90 | 105 |
| 3001 - 4500 | 60 | 75 | 90 | 105 | 120 |
| 4501 - 6000 | 75 | 90 | 105 | 120 | 135 |
| 6001 - 7500 | 90 | 105 | 120 | 135 | 150 |
| > 7500 | 105 | 120 | 135 | 150 | 165 |
Setting Ventilation Time
Step 2. Determine the ventilation controller fresh air delivery rate.
Measure the negative static pressure of the return system and consult the table below for approximate inlet airflow. These values are not absolute. An airflow measuring device (Nailor-Hart, etc.) will give the Ventilation Controller's airflow exactly. For the table below, the flex duct is laid loose with 2 wide 90° bends, and the damper is full open. For the rigid pipe the values are based on two 90° elbows, and the damper is open. For both cases the air intake is through a metal vent hood with a bird screen. Adjust airflow up or down for variations, including elbows or bends, or if the length of duct you're using isn't listed, etc.
Measure the delivered airflow or determine from above chart and record __________
| Duct Length | Negative Static Pressure ("w.c.) as Measured for Return Duct or Plenum | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.05 | 0.1 | 0.15 | 0.2 | 0.25 | 0.3 | |||||||
| Flex | Pipe | Flex | Pipe | Flex | Pipe | Flex | Pipe | Flex | Pipe | Flex | Pipe | |
| 10 ft. | 60 | 65 | 85 | 90 | 105 | 110 | 120 | 125 | 135 | 140 | 150 | 160 |
| 20 ft. | 55 | 60 | 80 | 85 | 100 | 105 | 115 | 120 | 130 | 135 | 140 | 150 |
| 30 ft. | 50 | 55 | 75 | 80 | 95 | 100 | 110 | 115 | 125 | 130 | 130 | 140 |
Step 3. Determine the ventilation controller knob setting.
Use your entries from Steps 1 and 2 in the table below. From this you can determine the correct knob setting. For example, if 80 CFM is required, and the Vent delivers 120 CFM set the knob to 40 minutes. If more outdoor air is required, increase delivered CFM by reducing bends in duct, increasing duct size, adding a second duct, or adding a powered fan.
| CFM Delivered | CFM Required | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 | 110 | 120 | ||
| 60 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 | 110 | 120 | |
| 80 | 15 | 25 | 30 | 40 | 45 | 55 | 60 | 70 | 75 | 85 | 90 | |
| 100 | 15 | 20 | 25 | 30 | 35 | 40 | 50 | 55 | 60 | 65 | 70 | |
| 120 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | 60 | |
| 140 | 10 | 15 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | |
| 160 | 10 | 10 | 15 | 20 | 25 | 25 | 30 | 35 | 40 | 45 | 50 | |
System Checkout
- Turn the time setting knob to the TEST/RESET position. If the installation is correct the HVAC blower will turn on (independent of heat or cooling operation) and the damper will open for 1 minute unless the knob is turned off of TEST/RESET. If the system does not operate see the Troubleshooting Guide.
- Return the time setting knob to the calculated setting. Do not leave in TEST/RESET, the Ventilation Controller will not operate.
Troubleshooting
Technical support is available Monday through Friday, 7:00 a.m. to 5:00 p.m. CST, at 800-334-6011. Use the troubleshooting guide to identify and correct system faults. Contact technical support before replacing the controller or damper, and for additional troubleshooting.
Table 4 - Troubleshooting Guide
| Symptom | Troubleshooting Procedure |
|---|---|
| HVAC Blower does not turn on in Test Mode. | 1. Make sure HVAC equipment has power. 2. Check the wiring for R, C, W and G and Gf at both the HVAC equipment and the Ventilation Controller. 3. Check voltage across the Ventilation Controller R&C and C&Gf terminals. Voltage should be in the 22 VAC to 30 VAC range. |
| Damper does not open in Test Mode. | 1. Follow steps 1-3 above. 2. Check wiring diagram to make sure the damper is wired in series with the circuit board and transformer. |
Table 4 - Troubleshooting Guide (continued)
| Symptom | Troubleshooting Procedure |
|---|---|
| The damper does not open with the blower operating. | 1. The damper will not operate once the ventilation time interval has been met. For example, if the knob is turned to 5 minutes and 5 minutes has elapsed, the damper will close and it will stay closed until the next 1-hour interval. For all modes except Mode A: 2. If the Indoor RH is above 55% and the outdoor temperature is above 50°F the damper will not open because of the potential for excess humidity. 3. If the outdoor temperature is below 0°F or above 100°F the vent stays off. 4. Verify that the outdoor temperature sensor is located properly. See page 12. 5. Turbulence in the return duct, plenum or mixing box can give false readings. Confirm proper location. See pages 5-6. 6. In Mode B, a heat call is required for ventilation under 20°F. 7. In Mode D, a heat call is required for ventilation under 40°F. |
| Blower turns on unexpectedly. | If ventilation time has not been met, the controller will activate the blower. This is normal operation. |
Table 5 - Error Codes
| Displayed Error Code | Troubleshooting Procedure |
|---|---|
| Display Error Code: E1: RH Sensor | Rotate knob to the "Test/Reset" position. After 5 seconds, the green indicator will blink, resetting the error. If E1 returns, replace the controller. |
| Display Error Code: E2: Controller Knob | Rotate knob to the "Test/Reset" position. After 5 seconds, the green indicator will blink, resetting the error. If E2 returns, replace the controller. |
| Display Error Code: E3: Outdoor Temperature Sensor | 1. Make sure that the Outdoor Temperature Sensor is properly connected to the ODT terminals on the controller. 2. Measure the resistance of the ODT sensor by removing the wires from the terminals and measuring the resistance across the wires with an ohmmeter. Confirm the reading with the temperature in the table. If the resistance value does not match the temperature value, replace the ODT sensor. 3. Reset error by rotating knob to Test/Reset then back to the normal setting. Note: ODT must be installed for Mode B, C, and D. |
| Outdoor Temperature (°F) | Resistance (kΩ ±10) |
|---|---|
| -30 | 231.8 |
| -20 | 163.4 |
| -10 | 117.3 |
| 0 | 84.8 |
| 10 | 62.2 |
| 20 | 46.1 |
| 30 | 34.4 |
| 40 | 26.1 |
| 50 | 19.9 |
| 60 | 15.3 |
| 70 | 11.9 |
| 80 | 9.3 |
| 90 | 7.3 |
| 100 | 5.8 |
