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Parameters
10 . 7 Valve check
10 . 7 .1 Valve proving system
Parameter 51
Parameter 51 is used to define whether and at what
time in the BCU program sequence the valve check is
activated. This allows either the tightness of the gas
solenoid valves and the pipework between them to be
checked (tightness test) or the closed position of a so-
lenoid valve (proof of closure function) to be checked.
If the proof of closure function is activated, the closed
position of the gas solenoid valve at the inlet side is
checked using a POC switch.
Parameter 51 = 0: Off. No valve check is activated.
Parameter 51 = 1: tightness test before start-up.
Parameter 51 = 2: tightness test after shut-down. With
this setting, a tightness test is also performed after a
fault is reset and after mains on.
Parameter 51 = 3: tightness test before start-up and
after shut-down.
An additional bypass valve must be installed in gas sec-
tions with an air/gas ratio control. The valve allows the
closed air/gas ratio control to be bypassed during the
tightness test.
BCU 580 · Edition 11.15l
Parameter 51 = 4: proof of closure function (POC).
PZL
PZH
49
50
ϑ
1
2
µC
A signal is sent to the BCU via the POC switch on the
3
gas solenoid valve on the inlet side before burner start-
BCU 570..C1
up stating that the valve is closed. After burner start-up,
58
47
the signal must drop out to indicate to the BCU that the
M
valve is open.
PZL
V1
V2
GZL
14
13
45
P
>750°
TC
48
PDZ
95
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