5.Control system - Meibes

5. Control system
5.3.1 Explanation of menu items
5.3.2 Information menu
In this menu all the measured values of the temperature
sensor, volumetric flow metre as well as the control
system (system conditions) are displayed.
Status display:
Active 50 = Control system on domestic hot water
set temperature value of 50°C
Z - active 4 = Control system on circulation set
temperature value of 40°C
After-run = After-run of the circulation pump for
cooling down the stainless steel plate
heat exchanger (See 5.3.5)
Disinfection = Control system on disinfection
temperature
Off = No control system function active
5.3.3 Programming menu
The programming menu contains values which are to be
set by the end customer.
■ Heat transfer unit
Hot water – set value 50°C, adjustment range
45°C to 60°C for domestic hot water. Should this
value be increased, the 60°C temperature value of
the safety shutdown should also be increased, by
going in the basic setting menu, submenu
„Controller“. A blending valve should in any event be
installed on the freshwater station outlet!
Water temperature – operating mode:
cold, hot or timed heating.
Water temperature – cold 1) No heat exchange
media is added to the stainless steel plate heat
exchanger after hot water has been drawn off. It
remains at the lowest temperature level after
drawing off. This results in a favourable control
behaviour arising for the drawing off of hot water.
Water temperature – hot 1) 2) The stainless steel
plate heat exchanger is continuously kept at a
constant operating temperature. When there is a
deviation lower than the water temperature set value
minus hysteresis, the P1 is activated with a capacity
of 25 % until the water temperature set value has
been achieved. This happens provided that a temperature
is measured at T2 or at the “reheating” option
at T5 which is greater than that of the hold-warm
temperature. Should this condition not be fulfilled at
T2, the temperature is again requested after a resting
period of one hour.
Water temperature – timed heating 1) 2) For the
duration of the time slot the stainless steel plate
heat exchanger is kept warm.
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Water temperature – set value 2) 40°C, adjustment
range 20°C to 50°C for the hold-warm temperature
of the stainless steel plate heat exchanger for water
temperature – hot and water temperature – timed
heating.
Water temperature – Hysteresis 3 K, adjustment
range 1 K to 20 K for the water temperature set
value. Only visible if water temperature = hot or
water temperature = timed heating has been
selected!
Note: The water temperature – hot function should
be used if the buffer storage is located far from
the freshwater station and the system is
operated without circulation.
Hot water max. 5K (2 K – 10 K)
Hot water min. 5K (2 K – 10 K)
Testing period 5 min (1 min – 30 min)
An error message is displayed when the temperature
exceeds or is lower than the hot water set
value. When the threshold values are exceeded or
the temperature drops below these values, a fault is
generated after the preset monitoring period, and
output S2 is switched as a potential-free contact.
The output is reset once the temperature is again
within the temperature range or it can be reset in
the information menu/error message upon actuation
of the right key. This monitoring is only valid when
drawing off takes place – not during circulation!
■ Time slot
There are tree time slots available to set the
circulation. Should the switch-on and the switch-off
time be set the same, this time slot is no longer
active. For further circulation functions, see 5.3.3.
The time slots are also used for the water tempera-
ture - timed heating. (See 5.3.3)
■ Reheating
This menu item is only visible once the reheating
function has been activated in the basic setting
menu. If „absolute value” has been selected, „65°C
storage tank set value” will be displayed. This value
is adjustable between 20°C and 90°C. If „relative
value” is selected „15 K splay” is displayed here.
This value is adjustable between 2 K and 50 K.
For further information regarding functions, see
points 5.3.5 and 7.4. Storage tank set value = buffer
set value
■ Data logging
This menu is only visible if a data stick has been
connected to the front side of the control system.
Measured values can be recorded on this data stick.
In a measurement interval of 1 second (factory
setting) measured values for approx. 4.5 hours can
be logged. The data can be analysed at the plant
with special software.
■ Clock time
Submenu for setting the clock time, date and the day
of the week.