McDaniel Metals

Economizer 101

Economizers are designed to provide “free” air conditioning when outside conditions are appropriate. When the outside air is cool and dry enough, the economizer automatically opens to introduce the cool air to the interior space, thereby eliminating the need to run the air conditioning compressor.

If the outside air becomes too warm or humid, the economizer automatically closes the fresh air damper and the compressor engages to begin cooling the space mechanically.

If a two-stage thermostat is used, it is possible to use a combination of economizer and mechanical cooling to condition the space.

The economizer can also be set to allow a minimum amount of fresh air to enter the space when the equipment's indoor blower is operating.

Economizers are valuable tools to enhance indoor air quality, save energy, and prolong the life of the air conditioning equipment.

Figure 1: Depicts the Honeywell Jade Economizer unit, showing various electrical connections and controls.

Sequence of Operation

This sequence assumes employment of a single enthalpy economizer using a two-stage thermostat.

1. A call for cooling comes from the room thermostat.
2. The enthalpy sensor determines if the atmospheric conditions are conducive for using outside air for cooling. If YES, proceed to step 3. If NO, or if outdoor air temperature rises above the enthalpy set point, proceed to step 4.
3. The outside air dampers open and modulate to maintain a mixed air temperature (outside air + indoor air) of 53 degrees F. If the outdoor air is insufficient to satisfy the thermostat alone and a second stage of cooling is required, the compressor starts and works in conjunction with the economizer.
4. In a system with two compressors, if the thermostat is still not satisfied by the economizer and stage 1 compressor, the Jade control will energize the second compressor. (Proceed to step 5.)
5. Outdoor air dampers open to minimum position and the compressor engages to provide mechanical cooling.
6. When the thermostat is satisfied, the outside air dampers return to a minimum position.

Installation

Figure 2: Illustrates the installation of the economizer damper rack.

1. Open carton and inspect contents for shortages and damage.
2. Remove filter access and evaporator access panel from the package unit. Keep the screws from the evaporator access panel.
3. Slide internal damper rack into the opening until the outside flanges of the assembly nest inside of the posts framing the opening. (Refer to Figure 2).
4. Plug the 9-pin economizer plug into the matching 9-pin plug in the unit.
5. NOTE: Ensure neither the wire nor the plugs interfere with the movement of the dampers during operation. Install the bottom portion of the new access panel on the unit.
6. Secure access panel to the unit with the screws removed in Step 2.
7. Remove the blower access panel from the unit and mount the mixed air sensor to the blower housing. (Refer to Figure 3).
8. Feed the wire for the mixed air sensor back to the economizer and connect it on the side of the Jade control at MAT. (Refer to Figure 4).
9. Assemble hood per the instructions on page 2. (Refer to Figure 5).
10. Attach the hood to the side of the unit over the economizer damper in the place of the discarded evaporator access panel.
11. Power the unit and use the Honeywell Jade Economizer instructions provided and the 4-button interface on the Jade controller to configure the economizer for your application.
12. Replace filter access panel on the unit.

Hood Assembly

Follow these steps to assemble the hood:

1. First, put the top face down.
2. Attach the left side to the top using the screws provided.
3. Attach the right side to the top using the screws provided.
4. Slide two 13-3/4" x 18-1/2" mist eliminators into place between filter stops.
5. Attach the divider to the left and right sides using the screws provided.
6. Attach the back to the left and right sides using the screws provided.

The diagram visually guides the assembly of the hood component, showing the placement of the top, sides, mist eliminators, divider, and back panel.

Technical Details

Minimum Set Point Equation

The following equation may be used to set the minimum position. The mixed air temperature and outside air temperature may be discerned by looking at the status menu on the Jade controller.

Equation: (To X OA) + (Tr X RA) = Tm

• To: Outdoor air temperature
• OA: Percent of outdoor air
• Tr: Return air temperature
• RA: Percent of return air
• Tm: Resulting mixed air temperature

Example:

Fresh air required is 10% outdoor air. Outdoor air temperature is 60 degrees F. Return air temperature is 75 degrees F.

(0.1 X 60) + (0.9 X 75) = 6.0 + 67.5 = 73.5

Mixed air temperature will be 73.5 degrees F when the OA is 60 degrees F and the RA is 75 degrees F with 10% outdoor air.

Dimensions

Figure 5: A dimensional drawing showing key measurements for a component, with values such as 17.29, 11.97, 23.85, 9.58, 8.53, and 8.22 units.

Contents

Accessories / Capabilities

• Dual Enthalpy: Requires an additional C7400 enthalpy control installed in the return air duct.
• Demand Control Ventilation: Requires a CO2 sensor.
• Power Exhaust: DPE3672(2/4) power exhaust used in applications where barometric relief is not sufficient.
• Remote Minimum Positioner: For applications requiring minimum position adjustments inside the conditioned space.

Important Notes

• Please see enclosed brochure for Honeywell component troubleshooting instructions as well as instructions for heat pump set up.
• Heat pump applications require Goodman part number IRKT-01 isolation relay kit.
• The fresh air mist eliminator should be flushed periodically with warm soapy water.
• A two-stage thermostat is recommended with this accessory.

Wiring Diagram

The wiring diagram illustrates the connections for the Honeywell W7220 Jade Controller.

Key Components and Connections:

• Honeywell W7220 Jade Controller: Features terminals for MAT, OAT, S-BUS, IAQ 2-10, IAQ COM, IAQ 24V+, ACT 2-10, ACT COM, ACT 24V+, AUX2-1, OCC, E-GND, EXH1, AUX1-0, Y2-1, Y2-0, Y1-1, Y1-0, C, R.
• Actuator Connections: COM, 24VAC/DC, S-BUS (3, 4).
• Sensors:
  • Mixed Air Sensor (connected to C7250A1001): Wires connect to MAT terminals.
  • Outside Air Temperature (OAT) Sensor: Wires connect to OAT terminals.
  • Enthalpy Control (connected to C7400S1000): Wires connect to S-BUS terminals.
• Thermostat Connections:
  • Standard 24VAC/DC Room Thermostat: Terminals R, C, G, Y1, Y2, W1/O, W2 are connected to corresponding terminals on the W7220.
  • Color codes for the 9-pin plug are provided: (Y) Yellow, (P) Purple, (BL) Blue, (G) Green, (O) Orange, (R) Red.
• HVAC Unit Plugs:
  • Daikin Plug (9-pin): Connections for Y1, Y2, W1/O, W2, R, G, C, OCC.
  • Goodman Plug (9-pin): Connections for Y1, Y2, W1/O, W2, R, G, C, OCC.
  • Specific wire colors for Daikin (DCG/DCH) are noted for W1/O.
• Ground Lug: Provided for grounding.
• Molex Connector: Part number 3597706** 50048926-002 is referenced.

The diagram details the routing of wires from sensors and thermostat to the W7220 controller, and then to the HVAC unit's control board via specific plugs.