Baxi PRIME HT 240 Installers And Users Instructions page 20

15.4 ELECTRICAL CONNECTIONS TO A MULTI-ZONE SYSTEM
The electrical connections and settings needed to control a multi-zone central heating system vary depending on what
accessories are connected to the boiler.
To permit the boiler to handle requests from individual zones, turn the Summer/Winter selector (1 - figure 1) on the boiler's
front panel to Winter ( ) position.
a) Without a QAA73 temperature regulator:
Connect the switch for functioning in multi-zone mode in parallel to the "TA" terminals 1-2 on terminal board M1 as shown
in figure 12. Remove the default bridge.
Set the desired temperature with knob 6, figure 1, directly on the boiler control panel.
b) With the QAA73 temperature regulator:
Connect the switch controlling those zones not controlled by the QAA73 in parallel to the "TA" terminals 1-2 of terminal
board M1 as shown in figure 15. Remove the default bridge.
The zone controlled by the QAA73 is supplied by the zone 1 solenoid valve as shown in figure 15.
The QAA73 automatically controls room temperature in its own zone.
Use the boiler control panel to set room temperature in the other zones.
Figure 15
Case 1: installation without an outdoor temperature sensor:
Use the central heating temperature control knob (6 - figure 1) on the boiler's control panel to set central heating output
temperature to the various zones.
If heating requests are received simultaneously from the main zone controlled by the QAA73 and another zone, output
temperature will be the higher of the two values set on the QAA73 and on the boiler's central heating temperature control
knob.
Case 2: installation with an outdoor sensor:
Central heating output temperature to the various zones is determined by the electronic control card on the basis of ou-
tdoor temperature and the preset heating curve as described in section 15.3.
If heating requests are received simultaneously from the main zone controlled by the QAA73 and another zone, output
temperature will be the higher of the values set on the QAA73 and calculated by the boiler's electronic control card.
1 Zone
1 Zone
(QAA 73)
(ROOM THER-
MOSTAT)
solenoid valve
1 Zone
20
INSTRUCTIONS FOR THE INSTALLER
2 Zone 3 Zone
(ROOM THERMO- (ROOM THERMO-
STAT) STAT)
N Zone
(ROOM THER-
MOSTAT)