System Volume; Boiler Schematic; Central Heating Circuit - Baxi Luna 3 Comfort Series Installation And Servicing Instructions

Based on 30 p.s.i. / 2.11 bar safety valve setting
Vessel charge and initial system pressure
Total water content of system using 2.2 gal / 10 l
capacity expansion vessel
supplied with appliance
For systems having a larger capacity MULTIPLY the TOTAL system capacity in litres (gallons) by
the factor to obtain the TOTAL MINIMUM expansion vessel capacity required in litres (gallons)
note: When the boiler is operating at maximum operating temperature, providing heating with all radiators operating, the
pressure gauge should not indicate more than 25.5 p.s.i. / 1.8 bar. If the reading exceeds this figure an additional expan-
sion vessel is required.
central Heating Mode (Fig. 1)
1. With a demand for heating, the pump circulates water through the primary circuit. At a pre-determined flow rate the
central heating flow switch operates, initiating the ignition sequence.
. The main burner ignites at low rate, then the gas valve controls the gas rate to maintain the heating temperature mea-
sured by the temperature sensor.
3. When the flow temperature exceeds the setting temperature, a 3 minute delay occurs before the burner relights auto-
matically (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).
Key
1 Primary Heat Exchanger
2 Burner
3 Ignition Electrode
4 Flame Sensing Electrode
5 Gas Valve
6 Pump
7 Automatic Air Vent
8 Expansion Vessel
9 Plate Heat Exchanger
10 Flow Sensor with Filter
11 Boiler Drain Point
12 Pressure Relief Valve
13 Heating Return
14 Cold Water Inlet On/Off Valve and Filter
15 Gas Inlet
16 Domestic Hot Water Outlet
17 Heating Flow
18 Automatic By-Pass
19 Water Pressure Switch
20 Manometer
21 Domestic Hot Water Temperature Sensor
22 Three Way Valve
23 Three Way Valve Motor
24 Safety Thermostat
25 Central Heating Temperature Sensor
Fig. 1
InstructIons pertaInInG to tHe Installer

2.8 system volume

2.9 boiler schematic

central Heating circuit

7
bar 0.5
psi 7.25
Litres 120
(Can) gal 26.4
(USA) gal 31.7
0.0833
1.0 1.5
14.5 21.7
91 64
20 14
24 16.9
0.109 0.156
95.188.3 - GB