Fan-Powered Units - Trane Tracer Uc

On/Off Electric Reheat
The Airflow Setpoint Minimum Local Heat is enforced during reheat.
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When reheat is de-energized, the cooling minimum airflow setpoint is activated. Refer to
p. 51
Hot Water Heat
Two types of control of hydronic heat are supported:
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Fan-Powered Units

The UC400 controllers provide the following three (3) fan options when in space temperature
control mode:
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VAV-SVX07B-EN
Stage 1; energizes when the space temperature falls below the active heating setpoint and
minimum airflow requirements are met. When the zone temperature rises above the active
heating setpoint by 0.5°F (0.28°C), stage 1 is de-energized.
Stage 2; energizes when the space temperature is 1°F (0.56°C) or more below the active
heating setpoint, and is de-energized when the space temperature is 0.5°F (0.28°C) below the
active heating setpoint.
Stage 3; energizes when the zone temperature is 2°F (1.11°C) or more below the active heating
setpoint, and de-energizes when the space temperature is 1.5°F (0.83°C) below the active
heating setpoint.
and Table 7, p. 51.
ON/OFF
Refer to staged electric heat for operation. The main difference with ON/OFF hot water heating
is the control of a two position hot water valve instead of the contactor energizing an electric
heat strip. Refer to Table 6, p. 51
Modulating
Proportional hot water reheat uses 3- wire, floating-point-actuator technology. It is the same
operation for single duct units as it is for fan powered units. The local heating minimum airflow
setpoint is enforced during reheat. The water valve opens as space temperature drops below
the heating setpoint. A separate reheat proportional, plus integral control loop from that
controlling airflow into the room, is enforced. Water valve position is dependent on the degree
that the space temperature is below the active heating setpoint and the time that the space
temperature has been below the active heating setpoint. An additional ON/OFF remote heat
output is available and energized when the proportional valve is driven 100% open and de-
energized when the proportional valve reaches 50% open. When reheat is de-energized, the
cooling minimum airflow setpoint is activated.
Hydronic heat is enabled if there is no valid supply air temperature and disabled if the supply
air temperature is greater than the configured reheat enable setpoint.
Note: Steam is not supported.
One-speed ON/OFF series fan
One-speed ON/OFF parallel fan
Flow control parallel fan
Calibration, Operation Modes, and Control
and Table 7, p. 51.
Table 6,
53