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VAV-SVP01A-EN

Sequence of Operations

stratification may result in uneven air distribution and zone temperature complaints.
See

Table 11, p. 72

for single duct reheat operation and

Table 12, p. 72

for fan

powered reheat operation.

On/Off Electric Reheat

One, two, or three stages of staged electric reheat are available on single duct units and two sages
of electric heat are available on fan powered units. The heating minimum airflow setpoint is
enforced during reheat.

•

Stage 1 is energized 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.

When reheat is de-energized, the cooling minimum airflow setpoint is activated. See

Table 11, p. 72

for single duct reheat operation and

Table 12, p. 72

for fan powered reheat operation.

Hot Water Heat

Two types of control of hydronic heat are supported: On/Off and modulating.

Note:

Steam is not supported.

Hydronic heat is enabled if there is no valid primary air temperature. Hydronic heat is disabled if
the primary air temperature is greater than the configured reheat enable setpoint.

ON/Off Hot Water Heat

Refer to staged electric heat for operation. Difference is we are controlling a two position hot water
valve instead of contactor energizing an electric heat strip. See

Table 11, p. 72

for single duct reheat

operation and

Table 12, p. 72

for fan powered reheat operation.

Proportional Hot Water Reheat

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 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. If not already closed, the water valve fully closes when the zone
temperature rises above the active heating setpoint by 0.5 °F (0.28 °C). 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 See

Table 11, p. 72

for single duct reheat operation and

Table 12, p. 72

for fan powered reheat operation.