Trane VAV-SVN01E-EN, Trane manual Unit Information, Single-DuctUnits, Vcef, Dual-DuctUnits, Vddf

Unit Information

Single-Duct Units	Figure 1 –Typical Single-Duct Units
The basic unit consists of a sheet metal
casing with an air valve, which is used
to modulate the air being delivered into
the occupied zone.The unit is designed
to modulate either cooling or heating
air between the temperatures of 40°F
and 140°F. Air enters the air valve
through the round or rectangular inlet
and exits into the sheet metal casing to
be distributed to the zone either
through integral round outlets in the
casing or through rectangular duct
attached to the discharge of the unit.	VCCF
The basic unit can also be ordered with
factory-mounted electric or hot water
heating coils attached to the discharge.
(See Figure 1.)
These re-heat units are used primarily
to reheat air-to-zone temperature when
the load in the occupied space is low.
Primary air is modulated through the
VariTrane air valve by rotating the
damper blade. All air valves have a
round/rectangular inlet for easy fit-up
with incoming ductwork.
	VCWF

VCEF

Dual-Duct Units

Dual-duct units provide two air valves: one as heating primary air and the other as cooling primary air. Both discharge into the common outlet, which leads to the zone being con- trolled. (See Figure 2.)

The units are provided with a slip and drive rectangular duct connection or can be ordered with integral outlet plenum.

Sequencing of the hot and cold air valve is dependent upon job requirements. One typical control is the valves working in conjunction with each other to respond to zone temperature.

When the cooling valve becomes fully closed or reaches a specified minimum, then the heating valve will begin to modulate or vice versa.The typical result is that air flowing to the zone varies from the maximum down to a minimum and back up to a maximum as the load varies and as the controls would cause one air valve to close and the other to open.

Another typical application is when the unit provides a constant volume to the zone.When the zone sensor is tied directly to the heating valve, it will modulate the heating valve according to the zone temperature.

When the heating valve is fully closed or there is a call for cooling in the zone, the cooling valve will be at constant supply. As the space becomes too cool, the heating valve will modulate open, decreasing the cooling valve flow.The typical result is that the air flowing into the zone stays at a constant flow whether the unit is heating or cooling.

Figure 2 –Typical Dual-Duct Unit

VDDF

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