BCU 580 · Edition 11.15
89
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 solenoid 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 sections
with an air/gas ratio control. The valve allows the closed air/
gas ratio control to be bypassed during the tightness test.
Parameter 51 = 4: proof of closure function (POC).
PZL
PZH
BCU 570..C1
µC
P
49
13
14
50
47
58
48
TC
PZL
PDZ
M
>750°
ϑ
1
2
3
V1
V2
45
GZL
A signal is sent to the BCU via the POC switch on the gas
solenoid valve on the inlet side before burner start-up stating
that the valve is closed. After burner start-up, the signal must
drop out to indicate to the BCU that the valve is open.
Parameters