Issue:
How can I control a non-communicating split system with a VariTrac III CCP?
Resolution:
Yes. CCP3 can handle a split system.
The relay board has both Rc and Rh for the two different 24 VAC connections.
Rc powers G, Y1, and Y2.
Rh powers W1 and W2.
The Primary purpose of the optional relay board is to allow control of generic or non-Trane RTUs with the CCP.Â
Here is information from VAV-18 SVU01A-EN:
Also see Varitrac CCP III Optional Relay Board Wiring for more detail
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Voyager/Reliatel Rooftop Operation versus Binary Output Control
The VariTrac CCP automatically recognizes and communicates directly with a Voyager or Reliatel unit on the communications link. The relay board in the central control panel is not required. The VariTrac CCP controls Reliatel or Voyager rooftops directly via a Trane communications interface (TCI) mounted in the rooftop unit. The CCP automatically senses whether the Voyager or Reliatel unit is a heat pump. The VariTrac CCP uses an optional relay board with six binary output relays to control the stages of heating and cooling, and the supply fan on non-Voyager/ Reliatel air-conditioning units. The same relay board is used for heat-pump and 2- heat/2-cool operation. When controlling the HVAC unit with the relay board, the unit type (heat pump or 2 heat/2 cool) must be selected using the PC software or operator display. The default is 2 heat/2 cool.
2 Heat/2 Cool versus Heat Pump Operation
The VariTrac CCP automatically determines if it is controlling a Reliatel/Voyager 2 heat/2 cool or heat pump unit and configures the operating parameters (such as staging and supply air setpoints). Generic units controlled with the optional relay board must be configured as 2 heat/2 cool or heat pump through the operator display or PC software. This configures the binary outputs to control in the appropriate sequence. Proper relay function by mode is identified in the VariTrac CCP wiring schematic. The system default is 2 heat/2 cool.
Spare Binary Output Control
The sixth binary output on the optional relay board is an SPDT unpowered spare output relay. An entry in the PC software allows you to choose how the relay is controlled:
Ventilation. The spare output controls the outdoor air damper control. The output is energized when the CCP (all groups) is unoccupied. When the first group becomes occupied, the CCP enters the morning warm-up/precool mode and the spare output remains energized. The mode terminates when half of the occupied voting zones are satisfied or become opposite callers. Morning Warmup also terminates after two hours or if the systems heat/cool mode changes over. The spare output is de-energized when morning warm-up terminates.
H/C. The spare output is energized when the CCP is in cooling and de-energized when it is in heating.
I CS. The state of the relay is controlled by an upper-level system, such as Tracker or Tracer (currently not supported).
CO2. The relay is controlled by the CCP demand-controlled ventilation program and energizes when the CO2 alarm point is reached. This relay function can be used to reset the position of a ventilation damper on a non-communicating HVAC unit based on the zone CO2 level.
On a Voyager/Reliatel unit, the ventilation damper is commanded closed via the comm link. On non-communicating HVAC systems (relay board control), the ventilation damper is controlled by Spare Output Relay 6.
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Notes:
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Changes:
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Other Question/Problem/Cause Statements:
- How can I control a non-communicating split system with a VariTrac III CCP?
- What is the optional relay board used for?
- Can I control a non-communicating 2H/2C or heat pump air-conditioning unit with a Tracker system?Â
Facts:
- VariTrac III Central Control Panel (CCP)
- The VariTrac CCP uses an optional relay board with six binary output relays to control the stages of heating and cooling, and the supply fan on non-Voyager/ Reliatel air-conditioning units
Original wave: wave5289
Document Identifier: DOC-82016
Document Identifier: 82016