Firmware V1.4
20.05.2021
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To prevent the heat exchanger from overheating, the pump has an overrun of 150 seconds. If the HT function is
deactivated, the hot gas valve is closed first, and the hot water produced in the meantime is still discharged.
In addition, the controller monitors whether
sufficient heating power is available. This is assessed using two
criteria:
firstly by an adjustable spread between the CO
2
inlet temperature and the outlet temperature, and
secondly, the water inlet temperature must be lower than the CO
2
inlet temperature. If this is not the case,
the internal power signal HT is reduced to "0" after an adjustable delay and held at this value (during an
adjustable lockout time), and an alarm is issued.
In addition, the HT function also has the
optional "legionella function"
:
The legionella function is intended to prevent the development of legionella by cyclically (once a week)
requesting a higher temperature setpoint in the drinking water buffer. If a heat exchanger is used to heat a
drinking water buffer, then the "legionella function" required for this can be activated. If the function has been
activated, a separate legionella setpoint (all values can be parametrised) is transferred to the internal power
calculation on Mondays at 01:00 h and the relay output 7 (terminals 33/34) on the optional SIOX extension
module is set. This relay output can be used to control an additional heating rod in the drinking water buffer.
Note:
with the legionella setpoint can only be used if "HT" is not set
to "external" power signal!
The "legionella function" remains active until the upper buffer temperature has reached the legionella setpoint
or the maximum duration of the "legionella function" has expired. If the maximum duration is exceeded, a
message is sent to the system centre.
The relay output 7 described in the previous paragraph is now continuously available (without legionella
function). The heating rod connected there is switched on when the temperature falls below the limit
temperature "HT heating rod on" and is switched off again when the temperature exceeds the limit temperature
"HT heating rod off". It can thus be used as a backup heating system. There is no time-based monitoring, as is
usual with the legionella function. The basic requirements for heating via heating rod are:
High temperature heat recovery HT is selected.
A request of the higher level BMS on digital input 2 (terminals 52/53).
A temperature sensor, mounted on top of the buffer storage tank, Pt1000 input 13 (terminals 29/30).
If any of these 3 conditions is not met, the heating rod is switched off immediately. This also applies if a
temperature sensor is installed, but a sensor break is detected.
The following temperature sensors are available and must be connected correctly:
Water inlet
Water outlet
Hot gas inlet
Hot gas outlet
Buffer top (optional)
Buffer bottom (optional)
All temperature sensors are monitored for wire breaks by the controller and in the event of any failure
an alarm is immediately transmitted to the system centre. For details on the terminal assignment, see
Terminal Assignment of the Analogue Inputs