Check expansion vessel pressure (every year)
Isolate the boiler by the flow and return valves underneath the boiler.
(the 2 outer black handled valves).
Drain down the boiler and with the boiler still vented remove the dust
cap on the boiler expansion vessel. Check the pre-charge pressure of
the expansion vessel and ideally re-pressurise with nitrogen, otherwise
with air to 1 bar or in accordance with the static height of the heating
installation, if necessary. Ensure the drain off is open when
re-pressurising.
Refill boiler and allow boiler to carry out the air purge function for its
7 minutes.
Test expansion vessel re-pressurisation point with leak detection fluid
to ensure no pressure is leaking through re-pressurisation point after
this work.
Note:
The vessel can lose some of its charge pressure over time.
Also check whether the installed expansion vessel is adequate for the
system water volume.
Expansion vessel & repressurisation point
Note:
If the interior of the boiler looks heavily polluted with dust /
dirt, then a full service should be performed even with acceptable
combustion readings (CO/CO
2
ratio).
Flue gas analysis
Put the boiler back into operation and carry out a flue gas analysis
as described on page 22.
Always put back the cover after (maintenance) work and secure it with
screws
A
and
B
.
Note:
During routine servicing, and after any maintenance or change of
part of the combustion circuit, the following must be checked: -
Checking the CO
2
Check the CO
2
readings at full load and low load as described on page 22.
Checking flue integrity
The integrity of the complete flue system and the flue seals by
checking air inlet sample to eliminate the possibility of recirculation as
described in the installation & servicing instructions.
Checking CO readings and Combustion Performance (CO/CO
2
ratio)
Check CO readings and Combustion Performance as described in the
installation & servicing instructions.
The combustion reading (CO/CO
2
ratio) must be less than 0.004. If the
combustion reading (CO/CO
2
ratio) is greater than this, and the integrity
of the complete flue system and combustion circuit seals has been
verified, and the inlet gas pressure and gas rate are satisfactory either:-
• Perform the ‘Full Service’
• Perform ‘Setting the Gas Valve’
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