ESIE98–06A Functional Control
Part 2 – Functional Description 2–13
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1.8 Head Pressure Control for EUWA/Y15-30HC(Z)
Functional
description
The chiller types EUWA/Y15-30HC(Z) are equipped with a fan control to ensure the high pressure
when the ambient temperature is low. When no signal is sent, all fans rotate on high speed.
■ When the temperature decreases until 17°C, relay Ry1 switches on. A first set of fans turns to a
lower speed or switches off (reset at 19°C).
■ When the temperature decreases until 0°C, relay Ry2 switches on. A second set of fans turns to a
lower speed or switches off (reset at 2°C).
All chiller types EUWA/Y15-30HC(Z) are equipped with head pressure control (as part of the
standardized switch box). For the EUWY, head pressure control is not used to its full extend while its
operation range is limited to 15°C.
In the wiring diagram, this head pressure control is positioned in block J22. Refer to ‘Wiring Diagrams’
on page 1-34.
Illustration The following illustration clarifies the working of the head pressure control:
In the tables below you will find an overview of the relay and fans:
STEP 0 Ry1=OFF and Ry2=OFF all fans at high speed
STEP 1
Ry1=ON M11F M12F M21F M22F M31F M32F
EUWA/Y15HC H OFF M — — —
EUWA/Y20HC H OFF H OFF — —
EUWA/Y25HC H OFF H OFF M —
EUWA/Y30HCHOFFHOFFHOFF
STEP 2
Ry1=ON + Ry2=ON M11F M12F M21F M22F M31F M32F
EUWA/Y15HC M OFF M — — —
EUWA/Y20HC M OFF M OFF — —
EUWA/Y25HCMOFFMOFFM—
EUWA/Y30HCMOFFMOFFMOFF
17 1902
very highmedium high
ambient temperature (°C)
speed
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