Honeywell W7750A User Manual
EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER
7
74-2958—1
Control Application
W7750 systems in commercial buildings typically incorporate
a packaged air handler system that delivers a constant
volume of air at preconditioned temperatures to the zone
being served. Each zone is usually serviced by a separate
AHU; however, sometimes two or more AHUs service the
same zone. Note that the W7750 is not designed to control
Variable Air Volume (VAV) air handlers or Multi-Zone air
handlers, where one air handler simultaneously controls the
space temperature in many zones.
a packaged air handler system that delivers a constant
volume of air at preconditioned temperatures to the zone
being served. Each zone is usually serviced by a separate
AHU; however, sometimes two or more AHUs service the
same zone. Note that the W7750 is not designed to control
Variable Air Volume (VAV) air handlers or Multi-Zone air
handlers, where one air handler simultaneously controls the
space temperature in many zones.
The W7750 can control staged or modulating heating and
cooling coils, mixed air economizer dampers, and the system
fan. Control of heat pump units, where the compressor(s) is
used for both cooling and heating, is also provided. The zone
the W7750 services can use a T7770 or T7650 for space
temperature sensing and an L
cooling coils, mixed air economizer dampers, and the system
fan. Control of heat pump units, where the compressor(s) is
used for both cooling and heating, is also provided. The zone
the W7750 services can use a T7770 or T7650 for space
temperature sensing and an L
ON
W
ORKS
Bus network access
for users. Fig. 2 shows a typical W7750 control application.
Fig. 2. Typical W7750 control application.
Control Provided
The W7750 Controller is designed to control a single air
handler to maintain the units space temperature at the current
setpoint. Heating and cooling control is provided for either
staged or modulating equipment. Up to four stages of
mechanical cooling and up to four stages of heating are
allowed. Modulating outputs can be either floating type such
as a Series 60 control, or Pulse Width Modulated (PWM
W7750B,C only) control.
handler to maintain the units space temperature at the current
setpoint. Heating and cooling control is provided for either
staged or modulating equipment. Up to four stages of
mechanical cooling and up to four stages of heating are
allowed. Modulating outputs can be either floating type such
as a Series 60 control, or Pulse Width Modulated (PWM
W7750B,C only) control.
The economizer dampers can be controlled directly with
floating or PWM outputs, or indirectly using a digital output as
an enable/disable signal to a packaged economizer controller.
The economizer enable function, which decides when to allow
outdoor air to be used for free cooling, can be configured to
floating or PWM outputs, or indirectly using a digital output as
an enable/disable signal to a packaged economizer controller.
The economizer enable function, which decides when to allow
outdoor air to be used for free cooling, can be configured to
one of ten strategies based on the inputs. For more details,
see Appendix B—Sequences of Operation. When the
economizer position is controlled from the W7750, the
minimum position setting (for ventilation requirements) can be
adjusted based on indoor air quality (IAQ) needs in the space.
IAQ monitoring is provided through either a CO
see Appendix B—Sequences of Operation. When the
economizer position is controlled from the W7750, the
minimum position setting (for ventilation requirements) can be
adjusted based on indoor air quality (IAQ) needs in the space.
IAQ monitoring is provided through either a CO
2
sensor or a
digital input from a space-mounted IAQ limit switch.
For heat pump configurations, up to four compressors can be
controlled, along with up to four stages of auxiliary heat, and a
heat/cool change over valve. Including the supply fan, the
combination of these items may not exceed eight outputs if a
W7750B,C is used, or six outputs for a W7750A. (The eight
outputs on the W7750C consist of five digital and three analog
outputs.)
controlled, along with up to four stages of auxiliary heat, and a
heat/cool change over valve. Including the supply fan, the
combination of these items may not exceed eight outputs if a
W7750B,C is used, or six outputs for a W7750A. (The eight
outputs on the W7750C consist of five digital and three analog
outputs.)
WINDOW CONTACT
OCCUPANCY
SENSOR
SENSOR
M
OA TEMP
FILTER
FAN
COOL
COIL
COIL
HEAT
COIL
COIL
DA TEMP
RA TEMP
EXCEL 10
W7750
CVAHU
W7750
CVAHU
T7770 OR T7560A,B
RETURN
AIR
AIR
DISCHARGE
AIR
AIR
OUTDOOR
AIR
AIR
CEILING
ROOF
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M17488