Symbio™ 700 - Multi-Zone VAV Standalone Operation

Symbio 700  - Multi-Zone VAV Standalone Operation

Summary:

Variable Volume Discharge Air (VVDA) control uses available cooling capacity to deliver the required temperature at the discharge of the unit. In cooling modes, the control uses cooling sources to deliver air temperature as required by the Discharge Air Cooling Setpoint.

The way to get cool on a VAV unit is by the following configurations:

VAV Box Relay Output:
This binary output is provided by the controller to be optionally wired to VAV units in a Multi Zone-VAV system to coordinate system changeover to full airflow heating. The binary output is de-energized when the controller is operating in cooling modes. The binary output energizes when the heat type installed requires full airflow. See Maximum Heat below for more details.

VHR Relay provided, see unit schematic

Configure as follows:

• Go to Settings > View Configuration > Edit (Upper right-hand corner)
• Configure system type for > VVDA
• Configure Indoor fan Type for > Variable Speed
• Select Apply (Upper right-hand corner)

• Go to Settings to configure VAV setpoints

• System > Arbitration Method Request > Configure for Standalone Control

• Indoor > Duct Static Pressure Deadband BAS > 0.20 In (H₂O)

• Indoor > Duct Static Pressure Setpoint BAS > 1.00 In (H₂O)

• Indoor > Duct Static Pressure Setpoint High Limit Setpoint BAS 3.50 In (H₂O)

• Refrigeration > Discharge Air Cooling Setpoint BAS > 55.0 °F

Maximum Heat:
Maximum Heat is a heating mode of operation with the supply fan operating at maximum speed. The controller does not provide maximum heat; instead, the controller provides heat capacity per the Operating Mode and unit type.

VVDA:
Variable Volume Discharge Air control units will transition to Maximum Heat operation in heating modes (for example Morning Warm Up, Daytime Warm Up) when the installed heating capacity requires full airflow. Maximum Heat can also be a Heat Cool Mode Request command, which Symbio 700 will remain in the mode until the mode is released.

On the transition to Maximum Heat, the Symbio 700 will reduce the supply fan to minimum speed, energize the VAV Box Relay Output, and wait for the duration of the VAV Box Stroke Time (adjustable). The VAV Box Stroke Time allows the VAV boxes in the system to open. The supply fan speed will then increase to 100% or the maximum speed subject to the high duct static pressure limit. Once the supply fan reaches its allowed maximum speed, Symbio 700 will enable heating capacity control to Discharge Air Heating Setpoint Active. Ventilation is managed per the operating mode.

The transition from Maximum Heat back to modulating airflow control modes is as follows:

1. Heat capacity terminates (if active), and a 90-second post-heat timer begins
2. Supply fan speed slows to minimum speed, and a 3-minute minimum speed timer begins
3. VAV Box Relay de-energizes
4. When the 90-second post heat and 3-minute minimum speed timer expire, modulating airflow control is enabled, and operating mode transitions and capacity control are enabled

Duct Static Pressure Control:
Multi Zone-VAV equipment has variable speed supply fans and is often used in Variable Air Volume (VAV) systems consisting of ductwork serving multiple building zones and VAV boxes that control space comfort independent of the rooftop air handler. VAV boxes modulate air volume by a damper that opens and closes to maintain space comfort. In response, duct static pressure increases and decreases. The controller will modulate supply fan speed to maintain Duct Static Pressure relative to the Duct Static Pressure Setpoint.

Duct Static Pressure High Limit:
The controller operates the supply fan to maintain duct static pressure below the Duct Static Pressure High Limit setpoint. In the event that duct static pressure approaches the high limit setpoint, the controller will reduce and limit the supply fan speed.

Morning Warm Up: 

Click the link below

• https://tranesupport.zendesk.com/hc/en-us/articles/12116225076621-MZVAV-Morning-Warm-Up

Daytime Warm Up:

Click the link below

• https://tranesupport.zendesk.com/hc/en-us/articles/12116581851789-MZVAV-Daytime-Warm-Up

Notes:

• Unless a 10KΩ @ 77° sensor is installed on the Symbio 700 UC J19-1 and J19-2 the unit will only operate in the discharge air cooling mode.
• Morning Warm Up occurs when the unit transitions from unoccupied mode to occupied mode and the zone temperature is at least 1.5F lower than the Morning Warmup setpoint.
• When the Heat Cool Mode Request is Cool (the unit is providing cooling), if a valid space temperature is 3°F below the adjustable Daytime Warm-up Setpoint, the Daytime Warm-up operation initiates.
• Staged heat capacity – Full airflow control (100%

Service Test Mode

• Heat will not be allowed to come on until the unit has been in test mode for at least 6 minutes (adjustable 1-10 minutes, 1-minute increments) and the indoor fan is at 100%.
• 1-hour time duration

Enabling MWU and DWU

1. Go to Settings to configure VAV setpoints
2. Heat > Enable Morning Warm Up
3. Heat > Enable Daytime Warm Up

WARNING:

Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.