Product specifications

5. Inspecting the Ionisation flow.
The ionisation flow of the burner can be read off
via the Installer Programme of the control unit. The
ionisation flow should be greater than 40 for both
the low and high positions. If there are differences
the ionisation probe must be examined and replaced
as necessary (see Section 11.4). Press and hold the
'Set' button on the controller for 10 secs until a
capital 'A' appears on the central heating display.
Press the 'Hot water' button once. The ionisation
flow alternating with 'LL' for low burner rate will
be displayed. Press the 'Hot water' button again.
The fan will speed up, the burner will go to high
output, and 'HH' alternating with the ionisation
flow will be displayed. Press the 'Reset' button
twice to restore to normal operation. Record the
data on the Service card.
6. Inspecting the siphon.
Remove the siphon. Remove the cap from the
siphon at the bottom of the appliance and drain
contents into a suitable container. Replace cap
firmly, refill siphon with water and refit to boiler.
Check the deposits for the presence of aluminium
oxide. If a quantity of aluminium oxide is present,
this could indicate that the outlet casting requires
removal and cleaning (see Section 10.3). These
deposits, if excessive, could indicate that the boiler
heating output is not sufficient to meet the system
demand.
10.2 Auxiliary equipment inspection.
The annual inspection of the boiler's auxiliary
equipment comprises checking the following:-
1. Operation of safety relief valves.
2. Operation of pressure reducing valve.
3. Expansion vessels pre-charge.
1. Safety relief valves.
Three safety relief valves are fitted to the system,
two are external to the boiler and one internal. The
operation of the two external pressure relief valves
may be checked by rotating the cap of the valve
through 90º. The internal temperature and pressure
relief valve can be checked by lifting the lever. In
each case water should be discharged. This can be
heard and also seen in the discharge tundish. If
there is no discharge, check that the system is
correctly pressurised, and if so, replace the
defective valve. Finally, check that there is no
leakage when the valves are returned to their closed
position.
Note: Where HepVo trap is used, it is important
requirement to run water through it during the
annual inspection, to maintain its correct
functioning.
2. Pressure reducing valve
Turn off the cold water supply and remove the
pressure reducing valve's head from the UV3
manifold. Check the gauze filter and clean or
replace as necessary.
Turn the water supply back on and use a suitable
gauge to check that the water pressure at a hot
water tap is no higher than 3·5 bar (the correct pre-
set pressure). If the pressure is higher than 3·5 bar,
then replace the pressure reducing valve.
3. Expansion vessels
 Domestic hot water vessel. (Blue)
Turn off the mains cold water supply stop tap and
depressurise the domestic hot water system. Apply
a suitable air pressure gauge to the air valve on the
end of the vessel. The pressure should be 3·0 bar. If
less, restore the pressure. If the vessel fails to
pressurise, check and replace.

Heating system vessel (Red)
Isolate the boiler and depressurise the heating
system. Follow the procedure for the domestic hot
water vessel ensuring the pre charge pressure is as
stated on the expansion vessel label. (Normally 1·5
bar).
10.3 .Servicing the boiler.
Warning! Before servicing the boiler, isolate
the electrical supply and close the boiler's gas
service control tap. Allow the boiler to cool
before commencing work.
Gas soundness checks must always be carried out
following servicing of any gas-carrying component.
Following servicing work, electrical system safety
checks must always be undertaken using a suitable
instrument prior to reinstating the electrical supply
to the appliance.
Correct boiler servicing comprises the following:-
1. Cleaning the appliance outlet casting.
2. Inspecting the burner unit.
3. Cleaning the heat exchanger.
4. Inspect air supply/flue gas discharge system.
5. Unvented hot water tank inspection.
6. Cleaning the central heating filter in the
optional Pre-Assembled Pipework kit if
included (as shown in Section 7.14).
ATMOS MULTI Mk 2 version 2008
Page 41