HL 530 Training Panel Function of Gas Heater

1 radiator,  2 overflow valve,  3 secondary heat exchanger,  4 gas fitting, 5 expansion vessel,  6 circulating pump,  7 air bleed valve,  8 sight glass, 9 burner, flow-operated safety device, primary heat exchanger,  10 U tube manometer,  11 operating and controller unit in switch cabinet