Engineered Comfort Fan Coil Controller EZstat Especificações descarregar pdf (Página 28)

Installation and Operation Manual

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Fan Coil Controller – EZstat

EC-EZstat

Date: 9-2014 Supersedes: NEW

Engineered Comfort reserves the right to change any information concerning product or speciﬁcation without notice or obligation.

Page 28 of 36

 7.3 Automaccoolingandheangchangeover

The EZstat can be set to automacally change between the heang and cooling modes.

• If the space temperature rises above the acve cooling setpoint, the mode is set to cooling.

• If the space temperature falls below the heang setpoint, the mode is set to heang.

7.4 Scheduling occupancy

The schedule in the controller is a standard BACnet schedule object. It can be changed from the display by a technician

with Password 2 or a BACnet operator workstaon.

The internal occupancy schedule changes the EZstat between the occupied (ACTIVE) and unoccupied (INACTIVE) states.

7.5 Display blanking and backlight

The EZstat display and backlight can be set to take any of the following acons one minute aer the last buon is pushed.

• Display an analog clock instead of the temperature display.

• Dim the display to a preset level.

• Remain unchanged.

When the display is dimmed or the clock is visible, the display returns to normal when any buon is pushed.

7.6 Temperature sensing inputs

The EZstat includes inputs for sensing space, discharge air, and fan coil unit supply water.

Space temperature sensing

All models of EZstat include an internal temperature sensor for measuring space temperature. For remote temperature

sensing, an external, 10,000 ohm, Type II thermistor sensor or Nailor Part# H1‑1989 can be connected to terminals RS. If

the EZstat detects that a remote sensor is connected, the internal sensor is not used for determining space temperature.

Water temperature sensor

The Water Temperature Sensor input (WST) is a required sensor for two‑pipe fan coil units with both heang and

cooling applicaons. The EZstat is congured for a Type III thermistor sensor or Nailor Part# H1‑1764B to monitor water

temperature.

The water temperature can be monitored as an analog input and is also stored in an analog value object.

Discharge air temperature sensor

The Discharge Air Temperature (DAT) setup is a required for modulang valve applicaons. The EZstat is congured for a

Type III thermistor sensor or Nailor Part# H1‑0246 for DAT applicaons. Discharge air temperature can be monitored as an

analog input and is also stored in an analog value object.

The Loop 3 (CL_DAT_Loop) and Loop 4 (HT_DAT_Loop) modulate to the DAT set‑points. The valves are controlled o

these loops, while the DAT sensor is constantly monitoring the discharge air temperature.

7.7 PID control loops

A PID control loop calculates an error value from the dierence between the measured room temperature and the acve

setpoint. The error value is expressed as a percentage and is typically used in a BAS controller to control the state of

an output. When the dierence between the setpoint and room temperature is large, the error is large. As the system

reduces the dierence between the setpoint and space temperature, the error becomes smaller. In a simple example, if

the output of the PID loop that is controlling a modulang valve is 50% the valve would be opened half way; if the output

of the loop is 100% the valve posion is fully open.

The EZstat uses the heang and cooling PID loops which are implemented in all sequences.

The PID loops in the EZstat are standard BACnet objects.

 7.8 Valveoperaonforfancoils

Hot and chilled water valves are used for heang and cooling in the fan coil unit versions of the EZstat. The fan coil two‑

pipe programming includes also a method to determine supply water temperature.

  Modulangvalves

On a call for cooling or heang, a modulang valve will modulate from 0 to 100% over the rst half (0‑50%) of the PID

loop output controlling the valve. The EZstat supports both normal and reverse acon valves which can be set from the

user interface.

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