Cleaning The Cold Water Filter; Annual Service; Using The Siemens Qaa73 Temperature Regulator To Program Boiler Parameters - Baxi PRIME HT 240 Installers And Users Instructions

24. CLEANING THE COLD WATER FILTER (PRIME HT 280 - HT 330)
The boiler is equipped with a cold water filter placed on the hydraulic assembly. To clean it do the following:
• drain the DHW system from water.
• unscrew the nut on the flow sensing assembly (Figure 25).
• pull out the flow sensing device and its filter.
• remove the impurities.
IMPORTANT: in the event of replacements and/or cleaning of the O-rings on the hydraulic unit, do not use oil or grease
as lubricant but exclusively Molykote 111.
To ensure the boiler operates at peak efficiency, the following checks must be performed every year:
• check on the appearance and tightness of the gas and combustion circuit gaskets;
• check on the condition and position of the ignition and flame sensing electrodes (see section 19);
• check on the condition of the burner and its fixing to the aluminium flange;
• check for any dirt in the combustion chamber. Use a vacuum-cleaner for this cleaning operation;
• check that the gas valve is calibrated correctly (see section 16);
• check that there is no dirt in the siphon;
• check on the central heating system pressure;
• check on the expansion vessel pressure.

26. USING THE SIEMENS QAA73 TEMPERATURE REGULATOR TO PROGRAM BOILER PARAMETERS

You can use the QAA73 temperature regulator to access a number of parameters on the LMU 34 electronic control card.
Connect up the QAA73 as instructed in section 15.2.
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--2
Figure 26

25. ANNUAL SERVICE

3-- ----4
--5
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INSTRUCTIONS FOR THE INSTALLER
The editable parameters are those between 504 and
651. Proceed as follows to access these parame-
ters:
1) Simultaneously press keys 1 and 4 on the QAA73
temperature regulator for about 3 seconds. The
message "Initialising BMU parameters" appears
on the display.
2) Simultaneously press keys 1 and 2 for about 3
seconds. The message "Initialising BMU Service"
appears on the display.
3) Press keys 1 or 2 to scroll through the list of pa-
rameters.
4) To change the value of the selected parameter,
press key 3 or 4 to decrease or increase the value
respectively.
5) Press key 5 to enter the new values and exit pro-
gramming of the boiler's electronic control card.