Specified Controls SC-Z3-HCMS-ESP Installation And Operation Instruction Manual

SC-Z3-HCMS-ESP Installation and Operation Instructions
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302HC REV 1.2
OVERVIEW:
The SC-Z3-HCMS-ESP is a residential/light
commercial zone control panel that includes
integrated ESP static pressure control logic
designed to eliminate the need for a conventional
bypass damper when used with 3-wire zone
dampers.
SEQUENCE OF OPERATION:
The panel allows a single HVAC unit to have up
to three separate zones. Each zone is controlled
by its own thermostat. When a zone thermostat
calls for heating or cooling, the zones not calling
will have their dampers powered closed, and the
zones calling will have their dampers powered
opened. The heating or cooling equipment will
also be brought on.
As zone dampers open and close, the ZPA-SPS
Static Pressure Sensor continuously monitors
the system static pressure. If the static pressure
goes above the static pressure setpoint, the
panel will send a signal to all selected non-
calling zone dampers to start to open to a point
where the static pressure setpoint is maintained.
The SPS LED will come on with the non-calling
zone LEDs until the static pressure reaches
setpoint. The small amount of air allowed to
bleed into non-calling zones eliminates air noise
and assures proper airflow through the HVAC
system. This also prevents coil freeze up and
high temperature issues.
2 Heat / 2 Cool - Auto Changeover
First Call Priority - Time Share
with Integrated ESP Static Pressure Module
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When all calls are satisfied, all zone dampers will
go to the full open position provided none of the
thermostats are calling for ventilation mode. If
opposite calls take place, the first zone to call for
heating or cooling receives priority. When the first
call is satisfied, the system will changeover and
take care of the opposite call. If zones being
served (heating or cooling) have not been
satisfied within 20 minutes while an opposite call
is taking place, the system will changeover. When
the zone is satisfied or 20 minutes has elapsed,
the system will again changeover if an opposite
call exists. This is referred to as Auto-Changeover
- First Call Priority - Time Share. In the event of a
tie, cooling will receive priority.
HIGH AND LOW LIMIT PROTECTION:
The ZPA-DTS Discharge Temperature Sensor
should be mounted on the discharge air plenum of
the HVAC unit and wired to the DA terminals on
the panel. The sensor is used for both high
(adjustable) and low (fixed) limit protection. The
high limit setting can be adjusted using the two
slide switches located on the panel. (See switch
location and settings on page 2) Low limit is fixed
at 45° F. When the discharge air temperature rises
above the high limit setting or falls below the low
limit setting, the panel will cycle the equipment off
while the fan continues to run. The LIMIT LED
blinks when high or low limit is reached and a 3
minute time delay is activated to prevent short
cycling of the equipment.
VENTILATION MODE:
Zone ventilation is established by the individual
zone thermostat fan setting. When no calls are
taking place, any thermostat set in the fan AUTO
mode will not receive ventilation air and its zone
damper will be closed. Any zone thermostat set in
the fan ON mode will receive ventilation air and its
zone damper will be opened. Heating or cooling
calls take priority over ventilation mode. The ESP
function will continue to maintain the system static
pressure by modulating open non-calling
ventilation zones as required.
POWER REQUIREMENTS:
The panel is powered by a single 24VAC, 40VA
transformer. Never use the equipment
transformer.
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