Product specifications

As stated at the beginning of 8.1, a suitable
inhibitor must be added to the system water.
Note! For existing central heating systems, the final
system water must have a pH value of between 6.5
and 8.
8.2 Filling the domestic hot water system.
 Open the UV3 combined stop tap and pressure
reducing valve and allow the storage tank to fill
with water. Check the pipework and connections up
to the safety valves for leaks.
 Vent the domestic hot water system by opening
ll hot water outlets until water is discharged.a
 Turn off the hot water outlets once the
ischarge water is clear and free from impurities.d
 Check the system for water leaks, rectifying
where necessary.
Note! If there was any possibility of debris entering
the domestic hot water circuit during filling, the
filter on the UV3 pressure-reducing valve must be
removed and cleaned as necessary.
8.3 Appliance operation.
The appliance may be put into operation by the
follow procedure:-
 With the appliance manual gas tap in the 'Off'
position, switch on the electrical supply to the
boiler. If a letter 'L' appears on the diagnostic
display the boiler has been wired with reversed
Live and Neutral connections, and must be
corrected.
Check that the water pressure in the central heating
circuit is approximately 1.5 bar at the appliance. If
the central heating water pressure is below 0·5 bar,
or higher than 3 bar, a letter 'C' alternating with the
work status of the appliance will be shown by a
warning report on the diagnostic display. (see
Section 12.). If this report is shown, the appliance
will only run at its minimum capacity. Correct the
pressure before proceeding.
 Switch off the domestic hot water heating by
pressing the 'Hot water' button on the operating
panel. The 'On' indication light will go out.
 Open the appliance gas tap and purge the gas
supply if necessary via the measurement nipple
provided for measuring the inlet pressure (Fig. 29).
Figure 29:
 Set the room thermostat at its highest position.
The appliance will now start (status report Code 2
•).
If the hot water temperature is under 10ºC, the frost
protection will cut in and the boiler will
automatically revert to raising the hot water
temperature above 15ºC (status report Code 3
•).
Note! If air is still present in the gas supply, the
boiler's burner may attempt to ignite several times.
After four start attempts, a flame malfunction will
be indicated (flashing 3
•). If this occurs, unlock the
control unit by pressing the 'Reset' button. Once
fired, the appliance will run for the first 3 minutes
at the lowest capacity and will then switch to its
maximum capacity until the central heating water
temperature reaches 80ºC. The appliance modulates
between 80ºC and 90ºC.
The boiler is preset to give a maximum heating
flow temperature of 90ºC. On most installations, it
may be advisable to change this to 75ºC, in which
case the appliance will modulate between 70ºC and
75ºC.
To set heating flow temperature, press and hold
‘Set’ button for 10 secs, or until a capital ‘A’
appears in the status display (to access the
Installer’s Program). Press the ‘Set’ button 3 times
to obtain a capital ‘C’ in the status display. The
lower display will show 90. Press the ‘Hot water’
button twice to change to 75ºC. Press the ‘Reset’
button twice to exit the program.
ATMOS MULTI Mk 2 version 2008
Page 36