Specifications

B) Face and Bypass Damper Actuator
This non-spring return actuator is connected to 24 VAC power and is controlled with a 4-20 mA signal
from Analog Output 2 (AO2, #21). A 4 mA signal drives the damper into full bypass position (closed),
while a 20 mA signal drives the actuator to the full face position (open).
C) 2-Pipe Valve Controlled Unit
A proportional valve is used on all 2-pipe (steam, chilled water and/or hot water) units. The valve
actuator is connected to 24 VAC power and is controlled with a 0-20 mA signal from Analog Output 2
(AO2, #21). The valve will return to the full open position on a loss of power. A 0 mA signal drives the
valve fully open, while a 20 mA signal drives the valve fully closed.
D) 4-Pipe Valve Controlled Unit
A proportional valve is used control the heating valve (steam or hot water) as described above.
A floating point (tri-state) valve is used to control the cooling valve (chilled water). The valve actuator is
connected to 24 VAC power and will fully close on a loss of power. Binary (Relay) Output 5 (NO5, #13)
is energized to drive the chilled water valve open, while Output 6 (NO6, #15) is energized to drive the
chilled water valve closed.
E) Binary (Relay) Outputs
(1) Fan control - the Fan Relay (FR1) is connected to Output 1 (NO1, #5). This output is energized to
start the fan and de-energized to stop the fan
(2) DX cooling Control - On self-contained units and units with DX cooling, the DX control circuit is
connected to NO5, #13. This output is energized to start the compressor/condenser and de-
energized to disengage the compressor/condenser.
(3) Electric Heat Control - 1st stage electric heat relay (HR1) is connected to NO2 (#7). 2nd stage
electric heat relay (HR2) is connected toNO3 (#9). 3rd stage electric heat relay (HR3) is connected
to NO4 (#11). These outputs are energized to engage the electric heat stage and de-energized to
disengage the stage.
(4) Radiant Heat Control - when this option is ordered on units with water/steam heating, a relay (HR1)
is added to control radiant heat. The coil of this relay is connected to NO2, #7.
6) Sequences of Operation
The following sequences of operation detail each ASHRAE Cycle II control configuration.
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