Flues for heating boilers; oil and gas burners for industrial and domestic use; boilers and heating appliances, namely hot water boilers and central heating boilers; heating systems for residential and commercial buildings comprised of boilers, valves, pipes, manifolds, control panel switches, and electrical wire, all sold as a unit; air-conditioning, air cooling and ventilation apparatus and instruments; turbine ventilators; air purification units; fireplaces; control and safety accessories ...