EVCO S.p.A.
EV3 MVC & EVD MVC | Application manual ver. 1.0 | Code 144EV3MVI104
page 52 of 72
9.9 Constant capacity/pressure regulation
The controller can regulate the fan speed to maintain constant pressure or air capacity if the differential pressure sensor is configured
and not in alarm mode.
On the basis of the parameter C58 (capacity coefficient) value the regulation will be by pressure (C58 = 0) or capacity (C58 > 0). In
the first situation the value detected by the differential pressure probe will be the setting value (C56), while in the second situation it is
the value of the capacity calculated using the formula:
In the incremental neutral zone regulation is based on the values of the parameters C56 (setpoint) and C57 (neutral zone) with an
increase in the C12 speed when the value of the pressure/capacity falls below C56 - C57/2 and a reduction in the C12 speed when the
pressure/capacity value rises above C56 + C57/2. In this situation too, the action may be repeated if the condition remains above C13.
9.10 CO
2
regulation
The controller is able to keep the CO
2
value in the environment under control to guarantee maximum comfort. Regulation acts first on
the mixing chamber damper (if present) and then on the fan speed if the CO
2
probe is configured and not in alarm mode.
CO
2
control uses incremental neutral zone regulation with parameters C50, C51, C12 and C13. If the CO
2
concentration is too high
(above C50 setting plus half the neutral zone C51) the mixing chamber damper is gradually opened wider starting from the normal
open position (defined by its setting and the active timer setting) up to its maximum aperture (C07). If the situation does not return to
normal when the damper is open to its maximum degree (or if the damper is not present) the fan speed gradually increases, starting
from normal speed (as for its setting and the active timer setting) until it reaches maximum speed (C05). When the CO
2
concentration
falls below the setting minus half band the process is reversed and the fan speed gradually reduces down to normal speed, then the
damper returns to its normal aperture.
9.11 Humidity regulation
The controller is able to control the room humidity to guarantee maximum comfort both when the humidity needs to be reduced
(dehumidifying) and when it needs to be increased (humidifying). The dehumidifying processes in the summer and winter cycles are
different.
Winter dehumidifier
For environments that are also humid in winter (swimming pools for example) it is possible to use the extremely low humidity of the
external air to reduce the interior humidity. In this situation regulation happens by action on the mixing chamber damper and on the
fan speed if the dehumifier in hot mode (C45) is enabled and the Humidity probe is configured and not in alarm mode or the digitial
input Dehumidifier request is configured and active
.
The humidity is regulated in the incremental neutral zone by parameters C46, C47, C12 and C13. If the humidity is too high
(>C46+C47/2) the mixing chamber damper is gradually opened wider, starting from normal then up to maximum aperture. If the
situation does not return to normal when the damper is open to its maximum degree, the fan speed gradually increases, starting from
normal speed until it reaches maximum speed. When the humidity falls below the setting minus half band (C46-C47/2) the process is
reversed and the fan speed gradually reduces down to normal speed, then the damper returns to its normal aperture.
Summer dehumidifier
In the summer cycle the external air cannot cause an effective reduction in the environmental humidity, making it necessary to use a
cold coil possibly with post-heating of the air.
Regulation acts on the cooling resources if the dehumidifier in cold mode (C45) is enabled and the Humidity probe is configured and not
in alarm mode or the digital input Dehumidifier request is configured and active.
If required, the summer dehumidifier is activated when the humidity is greater than C46+C47 or the dehumidifier request digital input
is active. The process stops when the humidity falls below C46 or the digital input is deactivated.
The humidity is regulated in the incremental neutral zone by parameters C46, C47, C39 and C40 that activate the cooling resources
according to the heat regulation timings and methods.
Following dehumidification the environmental temperature is liable to fall below the active regulation setting (which is the cooling
setting for the time setting in progress, possibly in follow-on if the return/room probe and the supply probe are present). If this
happens and the second coil is present the post-heating function is activated with regulation in the incremental neutral zone. In this
form of regulation the hot coil power is increased (according to parameters C39/C40) when the temperature falls by C37/2 (regulation
band in hot mode) below the setting; the coil power is decreased if the temperature rises above the setting (without waiting for it to
rise by C37/2 above that value).
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