Viessmann VITOCROSSAL 300, Service Instructions Manual

Page: 12 / 36

Checking the diaphragm expansion vessel and system pres-
sure
Note
Observe the diaphragm expansion
vessel manufacturer's instructions.
Carry out this test on a cold system.
Pump controlled pressure maintaining systems
Note
In heating systems with automatic
pressure maintaining equipment and/
or de-gassing systems (operating
according to the pressure reduction
method for de-gassing), install a dia-
phragm expansion vessel (DEV) as
individual boiler protection.
The diaphragm expansion vessel
must have the following minimum size
(volume in litres), subject to the boiler
output:
up to 300 kW: 50 litres
up to 500 kW: 80 litres
up to 1000 kW: 140 litres
This diaphragm expansion vessel
reduces the frequency and severity of
pressure fluctuations; the service life
of the pressure pump is improved and
therefore the operational reliability
and service life of system components
increased.
Damage to the boiler or to other
system components may result if
these recommendations are not fol-
lowed.
Carry out all checks in accordance
with manufacturer's instructions. Limit
pressure fluctuations to the lowest
possible differential. Cyclical pressure
fluctuations and more significant pres-
sure differentials point towards a sys-
tem fault. Immediately remedy such
faults, otherwise other heating system
components may become faulty.
Further details regarding the individual steps
(cont.)
12
Commissioning, inspection, maintenance
56
92
405
GB