commercial water heaters: electric low capacity and high capacity, gas fired, special purpose, steam fired, indirect fired; residential water heaters: electric low capacity, gas fired and indirect fired
CSI code / Product type
22 33 30 Residential electric domestic water heaters
22 34 30 Residential gas domestic water heaters
22 35 00 Domestic water heat exchangers
22 33 30.16 Residential storage electric domestic water heaters