Checking The Safety Equipment Function; Checking The Diaphragm Expansion Vessel And System Pressure - Viessmann VITOCROSSAL 300 Service Instructions Manual

Commissioning, inspection, maintenance
Further details regarding the individual steps

Checking the safety equipment function

Check the safety valves, the water level
and pressure limiters in accordance with
manufacturer's details.

Checking the diaphragm expansion vessel and system pressure

Note
Observe the diaphragm expansion ves-
sel manufacturer's instructions.
Carry out this test on a cold system.
Pump controlled pressure maintain-
ing systems
Note
In heating systems with automatic pres-
sure maintaining systems and/or deaer-
ating systems (operating according to
the pressure reduction method for dea-
erating), we recommend the installation
of a diaphragm expansion vessel (DEV)
as individual boiler protection.
The diaphragm expansion vessel must
be able to hold the heating water expan-
sion volume inside the boiler and provide
a capacity of at least 35 l.
This diaphragm expansion vessel
reduces the frequency and severity of
pressure fluctuations; the runtime of the
pressure pump is improved and there-
fore the operational reliability and serv-
ice life of system components increased.
Damage to the boiler or to other sys-
tem components may result if these
recommendations are not followed.
12
Carry out all checks in accordance with
the manufacturer's instructions. Limit
pressure fluctuations to the lowest pos-
sible differential. Cyclical pressure fluc-
tuations and more significant pressure
differentials point towards a system fault.
Immediately remedy such faults, other-
wise other heating system components
may become faulty.
Diaphragm expansion vessel
1. Drain the system or close the cap
valve on the diaphragm expansion
vessel and reduce the pressure, until
the pressure gauge indicates "0".
Note
The pre-charge pressure of the dia-
phragm expansion vessel (p
prises the static system pressure
(p ) (= static head) and a supplement
St
(p = p + supplement).
0 St
The supplement is subject to the
adjustment of the high limit safety cut-
out.
For a high limit safety cut-out set to
100 ºC: 0.2 bar
110 ºC: 0.7 bar
(cont.)
) com-
0