OPERATION AND MAINTENANCE MANUAL
Wall Mounted 0121…0661
Monobloc Wall Mounted Unit - WMA/WMF 0121-0181-0251-0281-0331-0551-0661 - Rev. 2.0. - Date: 18-07-2000 EN
7 (32)
FUNCTION PRINCIPLES
(basic version – mechanical cooling)
Air from the room is taken in by the recirculating fan through opening (
I
),
cooled by the evaporator coil and delivered into the room through opening
(
M
). In “T” versions, the air may be heated by the electric elements (
H
) before
being delivered into the room.
Fig. 1
M
I
H
FREE COOLING
(WMF UNITS)
The free cooling cycle consists of the introduction into the room of fresh air when this is sufficiently cold to absorb
the thermal load of the room. The unit is fitted with a butterfly damper and two air intakes:
•
recycled air intake (on left hand diagram)
•
external air intake (on right hand diagram).
A.
NORMAL FUNCTION
(figs. 2a and 3a)
During normal function the damper (
S
) is positioned to take in air only from the room (arrow on the left), closing the
external air intake.
The air is filtered (
F
), cooled and dehumidified in the cooling coil (
E
) and returned to the room by the fan (
MVE
).
Cooling is via the cooling cycle, starting the compressor (
CP
).
B.
FREE COOLING (free cooling)
(figs. 2b and 3b)
As soon as the external air is of a low enough temperature to maintain the temperature in the room at the desired
level, the damper (
S
) changes position, delivering fresh air into the room instead of recycled. During free cooling
function, the compressor is off.
C.
MODULATING FUNCTION
(fig. 2c and 3c)
When the outside temperature falls further, the control system therefore changes the damper position to mix fresh
and recycled air to maintain room temperature at the required level. In any case, the temperature of the air taken in
is maintained above a pre-set minimum.
