ACME Koolmaster PP20-VS2 User Manual Download Page 28

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KOOLMASTER PP20-VS2 rev.00

KOOLMASTER PP20-VS2

6.5. Air Inlets

Principle of Operation

6.5.1.

The controller can control the opening of 2 air

inlets: the opening of the first inlet can either

be defined by a potentiometer or with a timer;

the second air inlet can only operate with a

timer. Set the operating mode of the first air

inlet in the Installation Setup (sec. 4.5).

When using inlets, the user has to associate
an inlet opening with the start-up of each fan
stage. As the room temperature increases and
new stages are activated, air inlets will open
or close accordingly

Inlet opening in minimum ventilation:

The

inlet is at its

“Closed”

position during the

“Off

Time”

portion of a minimum ventilation cycle

and opens to its minimum ventilation position
during the

“On Time”.

This is true as long as

the minimum ventilation speed is slower than
a user-defined fan speed

(“Min Fan Speed”).

If the minimum ventilation rate exceeds this
speed, the inlet position will start increasing
and will be defined as a function of the fan
speed. The inlet position will vary between its
minimum ventilation opening and the opening
defined for stage 1 max (the inlet will reach
this maximum position if the minimum ventila-
tion fan speed is of 100%).

Inlet Opening as a

Function of the

Minimum Ventilation

Speed

Min Fan

Speed

100%

Inlet Posi-

tion (%)

Min

Vent.

Speed

Min

Vent.

Opening

Closed

Stage 1

Max

Opening

Over-opening of air inlets:

A supplementary

stage can be defined in order to continue open-

ing air inlets beyond the activation tempera-

ture of the last ventilation stage. This over-

opening stage is used to direct the airflow

more efficiently during periods of warm

weather. When all reference points of ventila-

tion stages are defined, the user can specify

the temperature at which air inlets reach their

over-opening position (Start T° of the last

stage + over-opening bandwidth).

Opening Compensation as a Function of

Temperature :

A compensation can be used

to ensure a certain uniformity in the room

temperature. With this compensation, inlet

positions are automatically adjusted when the

reading of the inlet probes differs from the

ambient temperature reading. Refer to section

4.7.3 to assign probes to the air inlets.

The temperature compensation of the air

inlet is expressed as a percentage per degree

difference between the ambient temperature

and the average reading of the inlet’s probes.

It determines by how much an inlet must

open or close to help reduce the temperature

differences in the building. For each degree

above or below the average temperature, the

inlet will open or close using the compensa-

tion value assigned by the user. For example,

if the compensation value is set to 2%/°F

and the inlet’s probes read 3°F above the

average controller temperature, the inlet will

open 6% to help decrease the temperature

in that zone.

Security function (for potentiometer-based
inlets):

If the potentiometer is defective, the

controller will operate in security mode: if
the room temperature is 2°F (1.1°C) above
the set point, the inlet opens according to the
following cycle: 8 seconds ON, 60 seconds
OFF. If the room temperature is 2°F (1.1°C)
below the set point, the inlet closes according
to the same cycle.

6.5.2. Settings

Select:

Current Conditions (Main Menu)

Inlets*
Inlet 1 is already displayed; press Inlet 2 to

display parameter settings of Inlet 2.

* Accessible if at least one inlet is enabled in the

Installation Setup (section 4.5). A password may also

be required to access this menu (section 4.2).

Set the following parameters:

Inlet openings are defined as a percent-
age of their total opening time.

Position —

This is the current position of

the selected air inlet. This value cannot be
modified.

Hysteresis —

When the actuator isn’t moving,

a minimum opening or closing command is
necessary for the actuator to start moving.
This value is called the

“hysteresis”

and it can

be adjusted from 1 to 15 seconds (timer-
based inlet) or from from 1 to 10% (potenti-
ometer-based inlets). The hysteresis prevents
the actuator from moving constantly. Set it
to the desired value.

Air Inlet

Stage 1

starts

Stg 2

starts

Bandwidth

Min. Vent.

Stg 3

starts

Stg 4

starts

Room