Checking The Function Of The Safety Equipment; Checking The Pressure Switch Function; Checking The Temperature Controller Setting If A Building Management System Is Used (Dcc System); Expansion Vessel And System Pressure - Viessmann Vitocrossal 300 Service Instructions Manual

Commissioning, inspection, maintenance

Checking the function of the safety equipment

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

Checking the pressure switch function

Installation instructions in the "pressure switch
set"
Checking the temperature controller setting if a building management system
is used (DCC system)
!
Please note
Shutting down from full load can result in high
material stress and material damage.
If a system with a higher ranking building man-
agement system takes over the temperature
control of the boiler, adjust the settings at the
temperature controller TR. Set the electronic
temperature controller to at least 10 K below the
mechanical temperature controller.

Expansion vessel and system pressure

Note
Observe the manufacturer's instructions for the dia-
phragm expansion vessel (MAG).
Check when system is cold.
1. Drain the system or close the cap valve on the
expansion vessel and reduce the pressure until the
pressure gauge indicates "0".
Note
The pre-charge pressure of the expansion vessel
(p ) is made up of the static system pressure (p
0
(= static head) and a supplement (p
plement).
The supplement depends on the high limit safety
cut-out setting.
Supplement
100 °C: 0.2 bar (20 kPa)
110 °C: 0.7 bar (70 kPa)
18
2. If the pre-charge pressure of the expansion vessel
is lower than the value calculated using the for-
mula, top up with sufficient nitrogen to achieve this
value.
3. Refill with water until the charge pressure is 0.2
(20 kPa) higher than the pre-charge pressure of
the expansion vessel when the system is cold.
4. Mark this value on the pressure gauge as the mini-
mum charge pressure.
)
St
= p + sup-
0 St