Appliance Operation - Baxi Megao System 15 Installation And Service Manual

Boiler Primary Circuit
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Key
1 Heat Exchanger
2 Burner
3 Ignition Electrode
4 Flame Sensing Electrode
5 Gas Valve
6 Pump
7 Automatic Air Vent
8 Pressure Relief Valve
9 Boiler Drain Point
10 Gas Inlet
11 Boiler Flow
12 Boiler Return
13 Pressure Gauge
14 Automatic By-Pass
15 Water Pressure Sensor
16 Safety Thermostat
17 Temperature Sensor
18 Expansion Vessel
19 Return Temperature Sensor
20 Fan
© Baxi Heating UK Ltd 2015
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3.0 Appliance Operation

3.1
1. With a demand for heating or hot water, the pump
circulates water through the primary circuit. If the pressure is
at least 0.5 bar and the ignition sequence will start.
2. When the flow temperature exceeds the setting
temperature, a 3 minute delay occurs before the burner
relights automatically (anti-cycling). The pump continues to
run during this period.
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3. When the demand is satisfied the burner is extinguished
and the pump continues to run for a period of 3 minutes
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(Pump Overrun).
IMPORTANT: When the selector switch is in the '0'
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(Off) position the electrical supply to the boiler is
isolated. The boiler will not operate.
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3.2
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1. The frost protection mode is integral to the appliance and
functions when the selector switch (see Section 2.1) is in the
ON position (
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5° C then the boiler will fire on its minimum setting until a
flow temperature of 30° C is reached. Further protection
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can be incorporated by using a system frost thermostat.
3.3
1. With the selector switch (see Section 2.1) in the ON
position (
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minute in every 24 hours to prevent sticking.
Fig. 2
Operating Mode (Fig. 2)
Frost Protection Mode
). If the system temperature falls below
Pump Protection
) the pump will automatically operate for 1
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