Douwe Egberts Cafitesse 700, Back Office Manual

Page: 220 / 265

July 2004
5F - 18
Functions - cooling system
Heat sink (7)
• The heat sink (7) is a ribbed aluminium
structure that distributes the heat over a
large area so that this heat can then be
transferred to the surrounding air without
any considerable heat accumulation. (Fig. 1)
The typical heat sink temperature is approx.
16
°
C (61
°
F) above the ambient tempera-
ture.
• Soiling caused by dust and grease (espe-
cially in kitchens) can reduce the heat
transfer. As a result, not only the efficiency
of the cooling system is reduced but also,
in extreme cases, the temperature of the
heat sink and therefore the temperature of
the warm side of the Peltier element can
rise so high as to destroy the Peltier ele-
ment.
• Inside the dispenser an air filter sucks in
the air in order to protect from soiling. To
ensure correct cooling, it is important clean
this air filter regularly.
Despite the air filter, it is advisable to clean
the heat sink with a brush at each servic-
ing.
Fan (9)
• The heat sink (7) is cooled in the air
stream created by a fan (9). To ensure the
efficiency of the cooling system the fan is
required to operate perfectly. (Fig. 1)
Overheating protection (8)
• The overheating protection (8) consists of a
bimetal safety switch and is installed on the
heat sink. (Fig. 1)
• The overheating protection is series-con-
nected with the Peltier elements and inter-
rupts the electric circuit at heat sink tem-
peratures above 75
°
C (167
°
F)
±
5K.
• When the heat sink temperature drops
below 40
°
C
±
5
°
C (145
°
F
±
41
°
F)
again, it closes the electric circuit again.
It is necessary to reset the dispenser by
plugging the mains plug out and back in.
Permissible maximum ambient temperature:
• The cooling system is designed for an
ambient temperature of up to 32
°
C (90
°
F).
• For proper assessment of service use, the
average ambient temperature over a period
of, e. g., 24 hours is an important factor.
Error messages – cooling compartment
temperature:
• At cooling compartment temperatures
beyond the permissible range, the control
system generates the following error mes-
sages:
30: cooling box temperature is too high
T > 12
°
C (54
°
F)
31: cooling box temperature is too low
T < 1
°
C (33.8
°
F)
• The first error message typically occurs
following a longer interruption of the power
supply.
• When the cooling system starts up, it takes
approx. one hour before the cooling com-
partment cools off from a usual ambient
temperature (approx. 25
°
C (77
°
F)) to less
than 6
°
C (42.8
°
F) (message goes out).
• This error can also occur whenever the
dispenser is filled with impermissibly warm
product packs or warm containers.
• An important fact that must be taken into
account is that the cooling system can
merely keep the concentrate in a cool state.
Cooling down the concentrate can take
several hours even if the cooling compart-
ment has already reached the correct
temperature in the meantime.
• The second error message can occur at
ambient temperatures < 1
°
C (33.8
°
F). The
main reason for integrating this error mes-
sage was to detect electric faults (in the
sensor circuit).
• The error messages are normally reset
automatically as soon as the permissible
cooling compartment temperature is
reached again.
• However, if the a cooling compartment
temperature of T < –1
°
C (30
°
F ) or T >
30
°
C (86
°
F) is measured over a period of
more than 3 hours, the errors 30 or 31 are
registered in the error report.
Cafitesse 700 - Functions - cooling system