Boilers and water heaters, domestic, gas, Heating, ventilation, air conditioning (HVAC) and refrigeration equipment, Construction, Water heaters, gas, domestic, Valves, metal, solenoid operated, Metal pipework, valves and containers, Valves, cocks, taps and fittings, metal, by type, Valves, metal, motorised, for fire protection systems, Valves, cocks, taps and fittings, metal, by use, Control systems, automatic