Trane Tracer VV550 User Manual

68 CNT-SVX17G-EN
Sequence of Operations
For staged electric ventilation flow control, the number of installed stages can range from
one to three. Three stages are recommended, since finer control is available with more
stages. In cases where the outdoor air temperature is more than 48°F (26.67°C) below the
discharge air temperature setpoint, the controller cannot provide the requested control
performance.
The controller provides no cooling capacity. If the outdoor air temperature (OAT) is above
the discharge air temperature setpoint, the discharge air temperature cannot be
controlled and the discharge air temperature is equal to the OAT.
Staged Hot Water Reheat Control
Units equipped with hot water coils should be sized so the maximum temperature of air
leaving the coil does not exceed 140°F (60°C F). Since only one stage of hot water reheat
is available, staged hot water does not allow tight control of the discharge air
temperature. Although the controller operates in this configuration, it is not
recommended.
Staged Reheat Control Algorithm (Integral Only)
An incremental form of the integral PID algorithm computes the desired level of reheat
capacity. The algorithm is run once every 10 seconds.
Modulating Reheat Control (Hot Water Only)
Units equipped with hot water coils should be sized so the maximum temperature of air
leaving the coil does not exceed 140°F (60°C). If hot water reheat is installed, the preferred
method of control is with a modulating valve. The modulating valve enables an
instantaneous discharge air temperature within the dead band of the discharge air
temperature setpoint. The reheat capacity algorithm for modulating hot water discharge
air temperature control is the same algorithm used to control modulating hot water
valves for a space temperature controller.
Modulating Reheat Control Algorithm (Proportional-Integral)
An incremental form of the proportional integral algorithm runs once every 10 seconds
and calculates the reheat capacity required to meet the discharge air temperature
setpoint. The required capacity is equal to valve position.
Freeze Protection (Hot Water Only)
Units with hot water coils installed are susceptible to freezing. It is important to prevent
the water coils from freezing. Freeze protection occurs only when the controller is in the
Off state or during the unoccupied period when the primary air valve is closed and the
reheat is disabled. During occupied operation, the control algorithm indirectly provides
freeze protection.
Network Controller Freeze Protection
Controllers that are connected to a LonTalk
®
network use the communicated source
temperature. If the value of the communicated source temperature drops below the

Trane Tracer VV550 Specifications

General

Brand	Trane
Model	Tracer VV550
Category	Controller
Language	English