Checking The Gaskets And Thermal Insulation Sections On The Boiler Side; Checking The Expansion Vessel And System Pressure; Checking The Water Quality - Viessmann Vitocrossal 100 Series Service Instructions For Contractors

Checking the gaskets and thermal insulation sections on the boiler side

A
B C
Fig. 19
1. Check gaskets on boiler flue connection
A
leaks.
Note
In full load operation, the gaskets can be checked
with an inspection mirror. If required, remove the
thermal insulation components. Traces of conden-
sate on the outside of the boiler flue connection are
also a sign of leaks.
Note
Before removing the boiler flue connection, discon-
nect plug at flue gas temperature sensor

Checking the expansion vessel and system pressure

Note
Check when system is cold.
1. Drain the system or close the cap valve on the
expansion vessel. Reduce pressure until the pres-
sure gauge shows "0".
2. If the pre-charge pressure of the expansion vessel
is lower than the static system pressure, top up
with nitrogen until the pre-charge pressure is 0.1 to
0.2 bar (10 to 20 kPa) higher.

Checking the water quality

Enter the amount of top-up water and the total hard-
ness of the feed and boiler water into the table in the
appendix (page 128).
For water quality requirements, see page 126.
Commissioning, inspection, maintenance
2. Check the fittings on the heating water side for
leaks and replace the seals/gaskets if required.
Danger
There is a risk of injury when working on
pressurised components.
The connections on the heating water side
must only be opened after the boiler has
been depressurised.
Only drain the boiler with a suction pump
when the boiler air vent valve is open.
3. Check the boiler thermal insulation for good fit and
correct if required or replace if it is damaged.
Reassemble if the boiler flue connection was
removed:
1. Push the boiler flue connection onto the flue outlet
for as far as it will go.
B
2. Secure with two M 8 screws; torque 18 Nm.
3. Push plug onto flue gas temperature sensor
C .
3. Top up with water until the charge pressure of the
cooled system is 0.1 to 0.2 bar (10 to 20 kPa)
higher than the pre-charge pressure of the expan-
sion vessel.
Permiss. operating pressure: 6 bar (0.6 MPa)
Minimum operating pressure: 0.5 bar (50 kPa)
Note
The minimum operating pressure is essential for
safe operation. It can be ensured with a minimum
pressure switch (one per system for multi boiler
systems).
The total hardness of the feed and top-up water must
not exceed the standard values specified by VDI 2035
(see page 126).
The pH value should be between 8.2 and 10.0.
.
C
25