Baxi HT 1.850 Installation, Operation And Maintenance Manual page 20

The pumps of the heating system (P1 and P2) have to be connected to boiler terminal block following the wir-
ing of gure 9, a relay must be wired between the boiler control circuit board and the pumps.
Figure 9
12.3 DESCRIPTION OF THE ELECTRICAL CONNECTIONS TO THE BOILER
Turn the control box downward to access terminal blocks M1 and M2 used for the electrical connections by
removing the two protective covers (see gure 8).
Terminals 1-2: connections for the optional SIEMENS QAA73 temperature regulator. These connections do
not have any speci c polarity.
Remove the bridge between terminals 1-2 "TA" on terminal
Read the instructions provided with the temperature regulator to ensure correct installation and programming.
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: oor 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).
ISTRUCTIONS PERTAINING TO THE INSTALLER
hydroheat.com.au
12.2 CONNECTING THE PUMPS
Cover
Terminal board
block
20
Terminal board
Cover
Terminal board
M1.
910.026.1 - EN (AUS)