Baxi 47 075 35 Installation & Servicing Instructions Manual page 9

1. With a demand for heating, the pump circulates water through the primary circuit.
2. Once main burner ignites the fan speed controls the gas rate to maintain the heating temperature measured by the temperature
sensor.
3. 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.
4. When the demand is satisfied the burner is extinguished and the pump continues to run for a period of 3 minutes (Pump Overrun).
Central Heating Circuit
Fig. 2
Key
1 Primary Heat Exchanger
2 Burner
3 Ignition Electrodes
4 Flame Sensing Electrode
5 Gas Valve
6 Pump
7 Automatic Air Vent
8 Plate Heat Exchanger/Automatic By­pass 22 Diverter Valve Motor
9 Flow Sensor with Filter & Regulator
10 Pressure Relief Valve
11 Boiler Drain Point
12 Heating Return
13 Cold Water Inlet On/Off Valve and Filter
3.2 Domestic Hot Water Mode (Fig. 3)
1. Priority is given to the domestic hot water supply. A demand at a tap or shower will override any central heating requirement.
2. The flow of water will operate the Hall Effect Sensor which requests the 3 way valve to change position. This will allow the pump to
circulate the primary water through the DHW plate heat exchanger.
3. The burner will light automatically and the temperature of the domestic hot water is controlled by the temperature sensor.
4. When the domestic hot water demand ceases the burner will extinguish and the diverter valve will remain in the domestic hot water
mode, unless there is a demand for central heating.
Domestic Hot Water Circuit
14 Gas Inlet
15 Domestic Hot Water Outlet
16 Heating Flow
17 Pressure Gauge
18 Water Pressure Sensor
20 Fan
21 Diverter Valve Assembly
23 Domestic Hot Water Flow Temperature Sensor
24 Safety Thermostat
25 Central Heating Temperature Sensor
26 Expansion Vessel