EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER
74-2958—158
Fig. 47. Setpoint ramping parameters with setpoint
calculation.
Durin
the COOL recover
period, the setpoint chan
es at a
rate in de
rees per hour relative to the outdoor air
temperature. If there is no outdoor air temperature sensor
available, the MinClRamp is used as the recover
rate.
See Fi
. 48 for the various setpoints.
Fig. 48. Setpoint ramping parameters with ramp rate
calculation.
NOTES: The setpoint used durin
the COOL recover
period
is similar to the heat mode in Fi
. 46, except the
slope of the line reverses for coolin
.
Recover
rampin
applies between scheduled heat-
in
or coolin
setpoint chan
es from UNOCCUPIED
to STANDBY, UNOCCUPIED to OCCUPIED, and
STANDBY to OCCUPIED. Scheduled setpoint
chan
es from OCCUPIED to UNOCCUPIED or
OCCUPIED to STANDBY do not use a ramped set-
point, but instead, use a step chan
e in setpoint.
Recover
ramps be
in before the next scheduled
occupanc
time and are ramped from the setpoint for
the existin
scheduled occupanc
state to the set-
point for the next occupanc
state.
FAN OPERATION
The W7750 suppl
fan can be controlled in one of two
different wa
s. In Continuous Fan mode, the fan runs
whenever the controller is in Occupied mode. When in
Standb
or Unoccupied modes, the fan c
cles on with a call
for coolin
or heatin
if the FanOnHtMode parameter is set
.
In Intermittent Fan mode, the fan c
cles on with a call for
coolin
or heatin
if the FanOnHtMode parameter is set
, and
c
cles off when the space temperature control is satisfied.
The fan control supports an optional
Proof of Air Flow
di
ital
input, that allows monitorin
of the suppl
fans status. If the
fan is commanded on, the Proof of Air Flow di
ital input is
checked up to three times to verif
that the fan is runnin
after
an initial dela
of FanOnDela
seconds
user-settable
. If the
fan fails to start the CVAHU must be reset b
first c
clin
CVAHU power. If this does not work, set DestManMode to
Manual and then back to Enable. After a reset the application
restarts—all outputs switch off and auto control is enabled.
Also, the W7750 Controller provides fan-run-on operation that
keeps the fan runnin
for a short time after heatin
or coolin
shuts off. The amount of time that the fan continues to run is
set in FanRunOnHeat for heatin
mode and FanRunOnCool
for coolin
mode.
WINDOW SENSOR (StatusWndw)
The di
ital input for a window contact provides the al
orithm
with a means to disable its temperature control activities if
someone has opened a window or door in the room. When a
window is detected to be Open
di
ital input contacts Open
e
uals window open
, the normal temperature control is
disabled, and the W7750 Controller enters the Freeze Protect
mode. Freeze Protect mode sets the space setpoint to 46.4 °F
8°C
and brin
s on the fan and heat if the space temperature
falls below this setpoint. Normal temperature control resumes
on window closure. The Window sensor si
nal can also be a
network input from another L
ON
W
ORKS
Bus device, so that no
ph
sical sensor is re
uired at the receivin
W7750 Controller.
SMOKE CONTROL
The Excel 10 W7750 Controller supports three smoke-related
control strate
ies:
1.
Emer
enc
Shutdown
all outputs off
.
2.
Depressurize
fan on, outdoor air damper closed
.
3.
Pressurize
fan on, outdoor air damper open
.
The controller is placed in one of these three control states
whenever the W7750 mode becomes
SMOKE_EMERGENCY, which can be initiated via a network
command
DestEmer
Cmd
or from a local
ph
sicall
connected
smoke detector di
ital input. When in
SMOKE_EMERGENCY mode, the W7750 Controller uses the
control strate
found in SmkCtlMode
one of the three listed
above
, and the normal temperature control function is
disabled. If a W7750 local smoke detector trips, the SrcEmer
network variable
for other L
ON
W
ORKS
Bus devices to receive
is set to the Emer
enc
state.
DEMAND LIMIT CONTROL (DLC)
When The L
ON
W
ORKS
Bus network receives a hi
h-electrical-
demand si
nal, the controller applies a DlcBumpTemp amount
to the current actual space temperature setpoint value. The
setpoint is alwa
s ad
usted in the ener
-savin
direction.
This means that if the W7750 Controller is in Coolin
mode,
the DLC offset bumps the control point up, and when in
Heatin
mode, bumps the control point down.
OCC setpoint
UN_OCC setpoint
OR
STANDBY setpoint
M10110
AUX HEAT
SETPOINT
HEAT PUMP
SETPOINT
(FOR COMPRESSORS)
RECOVERY TIME
OCCUPIED TIME
COOL RECOVERY
RAMP RATE
(DEGREES/HOUR)
MaxClRam
MinClRam
OaTempMinClRa OaTempMaxClRam
OUTDOOR AIR
TEMPERATURE
M10111
