WattMaster WM-WCC3-TGD-01B - Manual (Page 320)

WCC III Technical Guide 4-10
4. SCUSCR.EXE SCREENS
When the VAVBOX TUC-2R controller is in the Occupied
Supply Air Heating mode, the damper will be held at the Heating
Minimum position until the space temperature falls to within 0.5 ºF
of the Occupied Heating Setpoint.
As the space temperature falls below the heating setpoint,
the damper/airfl ow calculation causes the air valve to open
proportionally until the maximum setpoint is achieved at 1.5 ºF
below the setpoint. This is a 2 ºF proportional window starting 0.5
ºF above the heating setpoint to 1.5 ºF below the heating setpoint.
Two different confi gurations are available for the Occupied Space
Heating mode. If the box is confi gured to allow reheat during
HVAC Heat mode, the reheat relays can be activated even when
the VAVBOX TUC-2R controller is in the Supply Air Heating
mode. If the box is confi gured not to allow reheat when the HVAC
unit is in Heat mode, the box heat relays will be de-energized when
the VAVBOX TUC-2R controller is in Supply Air Heating mode.
In either confi guration, when the VAVBOX TUC-2R controller is
in the Supply Air Heating mode, the damper will modulate open
proportionally to the space demand. The proportional window for
the space temperature is 0.5 ºF above to 1.5 ºF below the heating
setpoint. This allows the space to take advantage of the warm
supply air in the duct.
The VAVBOX TUC-2R controller can activate auxiliary heating
relays if the Expansion module has been connected and the correct
number of heating stages (1, 2, or 3) has been confi gured. During
demands for heat, the fi rst stage will activate whenever the space
temperature drops below the heating setpoint. The second stage
will activate if the space temperature falls 1.0 ºF below the heating
setpoint. The third stage will activate if the space temperature falls
2.0 ºF below the heating setpoint. There is a two-minute delay
between staging. This prevents stages from activating at the same
time. Once a heating stage has been activated, it must remain on for
at least one minute. Once it has been deactivated, it must remain off
for at least two minutes. The third stage relay will deactivate when
the space temperature rises to within 1.0 ºF of the heating setpoint.
The second stage will deactivate when the space temperature rises
to the heating setpoint. The fi rst stage relay will deactivate when
the space temperature rises above the heating setpoint by 1.0 ºF.
Modulating (Proportional) Heat
The VAVBOX TUC-2R controller expansion board also provides
an analog output for control of a modulating hot water valve or
SCR electric heater. It provides a 0-10 VDC signal to control the
heating device. When the space temperature drops to 0.5 ºF above
the Heating Setpoint the output starts at 0 VDC and ramps up to 10
VDC at 1.5 ºF below the Heating Setpoint.
See Table 4-2: Relay Staging - Occupied Mode for a complete
layout of the various fan and heat relay staging points.
Box Fan Relay & Reheat Relay Staging Occupied Mode
Relays
Stage On
At
Series
Fan
Parallel
Fan
Heat
Stage
1
Heat
Stage
2
Heat
Stage
3
+0.5 F
Above
Box Heat
Setpoint
See
Note 1
See
Note 2
At Box
Heat
Setpoint
X
-1.0 F
Below
Box Heat
Setpoint
X
-2.0 F
Below
Box Heat
Setpoint
X
+1.0 F
Above
Box Heat
Setpoint
See
Note 1
See
Note 2
+1.0 F
Above
Box Heat
Setpoint
X
At Box
Heat
Setpoint
X
-1.0 F
Below
Box Heat
Setpoint
X
Note 1: The series fan will run continuously anytime the
VAVBOX TUC-2R controller is in occupied mode.
Note 2: The parallel fan will run whenever Space Heating Mode is
active. At all other times, the fan will only activate if the damper/air-
fl ow is below a user defi ned low limit setting.
WCC III VAV BOX III Operation Modes
Table 4-2: Relay Staging Occupied Mode