Baxi Power HT 1.850 Installation, Operation And Maintenance Manual page 92

12.3 DESCRIPTION OF THE ELECTRICAL CONNECTIONS TO THE BOILER
IT
Turn the control box downward to access terminal blocks M1 and M2 used for the electrical connections by
AT
removing the two protective covers (see figure 8).
Terminals 1-2: connections for the optional SIEMENS QAA73 temperature regulator. These connections do
not have any specific polarity.
GB
Remove the bridge between terminals 1-2 "TA" on terminal block M1.
Read the instructions provided with the temperature regulator to ensure correct installation and program-
ming.
Terminals 3-4: room temperature thermostat "TA". Thermostats with integral accelerator resistor must not be
used. Check that there is no voltage across the ends of the two thermostat connection wires.
Terminals 5-6: floor temperature thermostat connection "TP" (commercially available device). Check that there
is no voltage across the ends of the two thermostat connection wires.
Terminals 7-8: connections for the optional SIEMENS QAC34 outdoor temperature sensor. Read the instruc-
tions provided with the outdoor temperature sensor to ensure correct installation.
Terminals 9-10: connections for the optional domestic hot water priority sensor, for connecting single system
boilers to external DHW boilers.
Terminals a-b (230V AC; 50 Hz; 0,5 A max; cos ϕ > 0,8): electricity supply for boiler pump.
(Feeding relay coil).
12.4 CONNECTING THE QAA73 TEMPERATURE REGULATOR
The SIEMENS model QAA73 temperature regulator (optional accessory) must be connected to terminals 1-2
of terminal block M2 in figure 8.
The jumper across terminals 3-4, provided for connection of a room temperature thermostat, must be remo-
ved.
The settings of the domestic hot water temperature and domestic hot water production schedule must be made
using this device.
The timed program of the central heating circuit must be set on the QAA73 if there is a single zone, or in relation
to the zone controlled by the QAA73 device.
The timed program for the central heating circuit of the other zones can be set directly on the boiler control
panel.
See the instructions provided with the QAA73 temperature regulator for the user parameter programming
procedure.
IMPORTANT: For systems divided into zones, parameter 80 "HC2 gradient", which can be set on the
QAA73 temperature regulator, must be set as —.- "not active".
QAA73: parameters which can be set by the installer (service)
By pressing the two PROG buttons together for at least three seconds it is possible to access the list of para-
meters that the installer can display and/or set.
Press either of these buttons to change the parameter to display or change.
Press the [+] or [-] key to change the value displayed.
Press either of the PROG buttons again to save the change.
Press the information button (i) to quit programming.
Here follows a list of the most commonly used parameters:
92
INSTRUCTIONS PERTAINING TO THE INSTALLER