3.8 BOILER SCHEMATIC 16 17 15 18 14 19 13 20 12 21 11 22 10 23 9 24 8 7 25 6 26 5 27 4 28 3 29 30 2 1 31 Domestic hot water outlet Primary Heating return Primary Heating flow Gas Cold mains water inlet Condensate discharge and expansion relief 1 Gas isolation valve 12 Venturi 23 Boiler pump 2 Cold mains isolation valve 13 Primary flow temperature sensor 24 Primary pressure switch 3 Gas valve 4 DHW flow switch 14 Ignition/sensing electrode 15 Air supply pipe 25 DHW heat exchanger 26 Diverter valve 5 Gas injector 6 Flow regulator 16 Flue temperature sensor 17 Flue test point (pressure point +) 27 By-pass 28 Drain point 7 DHW temperature sensor 18 Air test point (pressure point -) 29 Safety valve indicator 8 Condensate trap 9 3 bar safety valve 19 Burner 20 Primary return sensor 30 Heating return isolation valve 31 Heating flow isolation valve 10 Expansion vessel 11 Venturi positive pressure point (+) 21 Fan 22 Automatic air vent Fig.
3.4 Alpha E-Tec 28 and 33 - Technical Data 9