DAB Advanced Hybrid AHU - Wiring/ Configuration

6 Minute Read

| Overview

The DAB Advanced Hybrid AHU is a profile that is used to control an AHU, which meet the HVAC demands of a space. The AHU supported is water a cooled AHU.

The profile supports up to four analog outputs for modulating cooling, heating, Fan speed and composite equipment, and also supports up to seven relay outputs for staged cooling, heating, Fan speed and humidification. Based on the preferences for the required conditioning, the controls required can be switched, set and used.

Since it is a combination of both staged and modulating controls, hence the name Hybrid.

| How it Works

Once you select the DAB Advanced Hybrid AHU profile from the system selection, all of the relays, analog outputs that are available as a part of the CM board of the CCU is made available in the profile screen to enable the conditioning required based on the preferences.

The Algorithm continuously track the average current temperature of the zones mapped as terminal profiles, under the DAB Advanced Hybrid AHU system profile, and looks for the change in the difference between the system level Desired Temperature and Average Current Temperatures and provides the required conditioning, either through the staged or modulating equipment.

When the Average Temperature increases above the set point or desired temperature and the zones demand cooling the cooling equipment stages are triggered based on the staged outputs or cooling equipment ramps up based on the or modulating outputs.

And when the Average Temperature decreases below the set point or desired temperature, and the zones demand heating equipment stages are triggered based on the staged outputs or heating equipment ramps up based on the or modulating outputs.

| Wiring

Below is a wiring schematic for the DAB Advanced Hybrid AHU, that show the connection from the CM board of the CCU to the AHU.

Note: The wiring schematic would differ for different control options set during the configuration.

| Configuration

Below is the configuration screen for the DAB Advanced Hybrid AHU, the control outputs are enabled or disabled based on the preferences.

Relays 1-6 - By default are configured as a traditional thermostat connection. However, depending on your equipment, you can reconfigure (Mapping) any of these relays to act as heating, cooling, or fan. 

Relay 7 - Auxiliary relay for humidifier or dehumidifier contact. This is a wet contact. If your equipment needs a dry contact, please see wiring information for which jumper to pull from the CM board. 

Test Signal - At any point you can override the value the output the algorithm decided. This is used for troubleshooting and testing your equipment. 

Analog-out1 - Cooling output scaled to the cooling load. 0Vdc = No cooling demand. 10Vdc = Max cooling demand. 

Analog-out2 -Fan Speed. Scaled based on the demand for pressure. 

Analog-out3 - Heating. Output scaled to the heating load. 0Vdc = No heating demand. 10Vdc = Max heating demand. 

Analog-out4 - Composite. This assumes no demand at the midpoint. Very configurable. (E.g. 5Vdc = No demand. 0Vdc = Max Cooling demand. 10Vdc = Max Heating Demand) 

Analog-out1-3at Min and Max - Set the minimum output at minimum load or maximum load. Typically synced with your equipment. 

Analog-out4 at Min and Max - Here you need to be careful because it is so customizable. Your Min can be more than the max values depending on unit configuration. What you need to know is that however you set this up, must be matched up with your unit. (A common example would be an RTU where you are setting up a DAT reset. AO4 @ Min Cooling = 5, AO4 @ Min Heating = 5, AO4 @ Max Cooling = 0, and AO4 @ Max Heating = 10V. Then you'd need to sync your DAT setpoints at the RTU to match. 0Vdc = 55F and 10Vdc = 100F)

Below the profile configuration is additional parameters for adjusting the analog output voltage to each piece of equipment.  You may program min/max output voltage for min/max system operation.

| Operations

Cooling

When the zones demand for cooling the algorithm calculates a loop output, which is based on the Proportional and Integral loop for control signals, called cooling loop output. This loop output which is in percentage is scaled to the different stages of cooling or voltages of the modulating output that is set during the configuration as below.

Staged Outputs

• Cooling loop output > 0%, Cooling Stage 1 Turns On
• Cooling loop output > 20%, Cooling Stage 2 Turns On
• Cooling loop output > 40%, Cooling Stage 3 Turns On
• Cooling loop output > 60%, Cooling Stage 4 Turns On
• Cooling loop output > 80%, Cooling Stage 5 Turns On

Modulating Outputs

• Cooling loop output <= 70%, Cooling Stage 5 Turns Off
• Cooling loop output <= 50%, Cooling Stage 4 Turns Off
• Cooling loop output <= 30%, Cooling Stage 3 Turns Off
• Cooling loop output <= 10%, Cooling Stage 2 Turns Off
• Cooling loop output <= 0%, Cooling Stage 1 Turns Off

Heating

When the zones demand for heating the algorithm calculates a loop output, which is based on the Proportional and Integral loop for control signals, called heating loop output. This loop output which is in percentage is scaled to the different stages of heating or voltages of the modulating output that is set during the configuration as below.

Staged Outputs

• Heating loop output > 0%, Heating Stage 1 Turns On
• Heating loop output > 20%, Heating Stage 2 Turns On
• Heating loop output > 40%, Heating Stage 3 Turns On
• Heating loop output > 60%, Heating Stage 4 Turns On
• Heating loop output > 80%, Heating Stage 5 Turns On

Modulating Outputs

• Heating loop output <= 70%, Heating Stage 5 Turn Off
• Heating loop output <= 50%, Heating Stage 4 Turns Off
• Heating loop output <= 30%, Heating Stage 3 Turns Off
• Heating loop output <= 10%, Heating Stage 2 Turns Off
• Heating loop output <= 0%, Heating Stage 1 Turns Off

Recirculate

When the zone demands recirculation along with cooling, the system will call for the staged or modulating fan speeds which is also based on the loop output that is calculated.