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2.2.4 Example 3 - Extra fail-safe supervision with pres-
sure differential switch (fig. 7)
The example shows how a pressure differential
switch (PDS) must be connected to an EBC12. The
pressure differential switch carries out extra fail-safe
supervision. With a PDS fitted, the boiler will not be
released, until both the pressure differential switch
(PDS) and the pressure transducer (XTP) have regis-
tered sufficient draught.
•
Connection to the pressure differential switch
(PDS):
• Remove the factory-fit loop between termi-
nals 16 and 18.
• Connect the pressure differential switch to
terminals 16-18.
• Connect the chimney fan to terminals 19-
21. Chimney fans with an integral pressure
differential switch (PDS) must be connected
to terminals 16-21 according to the instruc-
tions enclosed with the chimney fan.
•
The remaining terminals should be connected as
in example 1 or 2.
Below the connections of example 1 are shown.
Terminals (fig. 7)
1
Supply L1
2
Supply N
3
Supply PE
4-5
Boiler thermostat. Opto coupler (-)(10-230V)
6-7
Boiler thermostat. Opto coupler (+)(10-230V)
8
24V DC supply to voltage free contact (boiler
thermostat)
9
0V DC supply to voltage free contact (boiler
thermostat)
14
Burner relay switch Common (max. 230V AC
8A)
15
Burner relay switch Normally Open (max.
230V AC 8A)
16
PDS-C (Common) pressure differential switch
17
PDS-NC (Normally Closed) pressure differen-
tial switch
18
PDS-NO (Normally Open) pressure differential
switch
19
Chimney fan L1
20
Chimney fan Nreg
21
Chimney fan PE
22
XTP 0V supply (pressure transducer)
23
XTP 24V supply (pressure transducer)
24
XTP 0-10V signal (pressure transducer)
25
Control signal 0V
26
Control signal 0-10V
7
