Electrical Connections Of External Accessories - Siemens AVS 75.391 Handbuch

3.2

ELECTRICAL CONNECTIONS OF EXTERNAL ACCESSORIES

To connect the AVS75 accessory to the cascade accessories proceed as follows (use "HAR H05 VV-F" harmonised cables with
a cross-section of 1 mm ):
2
• Connect the cascade pump to the QX21 connector on the AVS75.
• Connect the cascade delivery sensor to the BX21 connector on the AVS75 (QAD36 supplied).
• Connect the cascade return sensor to the BX22 connector on the AVS75 (QAD36 available as an accessory).
• Connect the ambient thermostat to the H2 connector on the AVS75.
• If a DHW storage boiler is installed (see section 6.2), connect the storage boiler pump to the QX22 connector of the AVS75.
Connect the relative NTC probe to the M2 terminal block of the master boiler (see the boiler instructions manual).
KEY TO CONNECTORS
Connector linking the SIEMENS electronic board to
X50
the AVS 75 accessory via a flat cable
C (EX21-FX23) Not used for cascade arrangements
230V safety thermostat, not used for cascade
C (FX23-L)
arrangements
S (QX23-N) 230V programmable relay output
T (QX21-N) 230V relay output, CASCADE PUMP powering
230V relay output powering a DHW storage boiler
T (QX22-N)
PUMP
AVS 75 power input
N L (L-N)
n (H2-M) ROOM THERMOSTAT connector
n (BX22-M) CASCADE RETURN SENSOR input
n (BX21-M) CASCADE FLOW SENSOR input
M Common earth for sensors
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