BCU 580 · Edition 11.15l 30
Valve proving system
5.1.1 Test instant
Depending on the parameter setting, the tightness
control checks the tightness of the pipework and the
gas solenoid valves before each start-up and/or after
each shut-down of the burner, see page 95 (Valve
proving system).
The gas line is always safeguarded by a gas solenoid
valve during this check.
Before burner start-up
The valve check is started when the start-up signal ϑ1
is present at terminal 1. The BCU checks the tightness
of the gas solenoid valves and the pipework between
the valves. The gas line is always safeguarded by a gas
solenoid valve during this check. The pilot burner is ig-
nited when pre-purge is ended and the tightness has
been checked successfully.
After burner shut-down
After the burner has been shut down, the BCU checks
the tightness of the gas solenoid valves and the pipe-
work between them. Once the test has been carried out
successfully, the next burner start is enabled.
The BCU always conducts a tightness test if mains volt-
age is available or if it is reset after a fault lock-out.
An additional bypass/relief valve must be installed in
gas sections with an air/gas ratio control. This ensures
that the test volume V
p1
can be vented during the tight-
ness test with the air/gas ratio control closed.
BCU 580..C0F3
µC
VAS
VAS 1
VAG
V1 V2
V4
13 14 57
PZH
p
u
/2
45
V
p1
VAS
VAS 1
VAG
V1
V2
V3
V4
VAS 1
BCU 580..C0F3
µC
13 14 15 57
p
u
/2
45
PZH
V
p1
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