Two sizes allow multiple applications from 100k Btu to 220k Btu; cabinets are standard with front water access (refer to the chart below for specific applications). NOTE: Blower & Motor and Heat Exchanger Coil are sold separately. Air Handler Cabinet door is capable of holding a filter (not included). Some assembly will be required. If utilizing an existing 24-volt thermostat to control blower, a Fan Center Relay (p/n 515) must be used.