A humidifier for humidifying a flow of pressurized breathable gas to be delivered to a patient includes a dock and a humidification tub. The dock includes a device compartment that is configured to at least partially removably receive an RPT device that is configured to supply the flow of pressurized breathable gas. The dock also includes a humidification compartment that is fluidly connected to the device compartment. The humidification tub is configured to contain a supply of water and is at least partially removably received within the humidification compartment so that, in an operational configuration, the humidification tub is arranged to receive the flow of pressurized breathable gas and output the flow of pressurized breathable gas with increased humidity. The dock also includes a heater fixed to the humidification tub. The heater is configured to heat the supply of water.