Rev. d 01/1 38
DMP052E
EXAMPLE 4
:
RETURN AIR SYSTEM WITH ENTHALPY DAMPER CONTROL, ROOM TEMPERATURE AND
HUMIDIFICATION
Enthalpy damper control: THIS APPLICATION REQUIRES TWO W500H
Return air system with differential comparison of two Enthalpies (outside/inside) for damper
control, room temperature control with heating/cooling coil + limit function (anti-frost or max
temperature) on any of digital inputs.
OPERATION
The R1 controller time controls, with PI action, the room temperature on return air (sensor 2)
driving the valve (4) on heating/cooling coil. It controls “Direct” (Summer) or “Reverse” (Winter)
action depending on S/W changeover (6), from digital input DI2.
In winter time, the room humidity detected by transmitter (3) is maintained at set point by on/off
action of humidifier (9). The outside dampers (inlet and exhaust) and the return air one are
controlled by one analogue output only and by setting the correct direct/reverse action of the
relevant actuators (max outside opening=minimum return air system).
If the outside Enthalpy (detected by outside temperature sensor (10) and outside humidity
transmitter (11)) is higher than the internal one (return air temperature sensor (2) and return air
humidity transmitter (3)) , in winter outside air has priority and vice versa in summer. R1 controller
receives the information about outside humidity percentage via LinkBus, through the R2 controller.
ModBus supervision is possible.
Frost protection:
in case of heated fluid lack or of faulty control, if the anti-frost thermostat (5)
detects a temperature lower than the set value, the controller stops the fan and closes the outside
air and air-exhaust damper and contemporarily opens the return air damper.
