Baxi Luna HT 1.450 Notice D'installation Et D'entretien page 36

11.4.3 Two temperature zone with QAA 73
Fig. 28
In a two temperature application it is possible to avoid using a mixing valve or diverter valve by configuring your system
similar to the one shown in the above example. The boiler has the ability to set two separate loop temperatures as long as
one of the loops is being controlled by the QAA73 controller. The QAA73 loop better known as heating circuit 1 will take
priority over heating circuit 2 (controls conected to terminals 1 & 2 on the M1 bus terminal - fig. 23 - see Section 11.1),
therefore you will always want your high temperature zone to be controlled by the QAA73.When the QAA73 is calling the
NC and C terminals 1 & 2 on the M2 bus terminal will open breaking the circuit to terminals 1 & 2 on the M1 bus terminal
and resulting in a call for heat from heating circuit 1 only. Once the QAA73 has been satisfied the NC and C terminals on
the M2 bus terminal will close, if there is a call for heat from the thermostat connected to terminals 1 & 2 on the M1 bus
terminal the unit will being to heat heating circuit 2. The maximum loop temperature setpoin for heating circuit 1 can be
adjusted on line 72 (Section 12.6) of the QAA73 and the maximum loop temperature setpoint for heating circuit 2 can
be set by adjusting the central heating dial located on the front of the boiler. There is also the option to set two separate
heating curves in this aplication if utilizing a QAC34 outdoor temperature sensor (Section 11.3). You can set the heating
curve of heating circuit 1 on line 70 (Section 12.6) of the QAA73 and the heating curve of heating circuit 2 on line 532
(Section 12.5) of the QAA73.
INSTALLATION AND SERVICING INSTRUCTIONS 7110242.02 - en
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