A humidifier system for humidifying gas delivered to a patient, comprising: a water source (109, 509); a humidifier unit (107, 507) disposed on a patient circuit (103, 503) that provides gas to a patient, the humidifier unit (107, 507) located proximal to a patient interface (105, 505) of the patient circuit (103, 503), the humidifier unit (107, 507) comprising: a chamber (203, 603) that receives water from the water source (109, 509), a heat source (201, 601) disposed within the chamber (203, 603), a flow sensor (113, 513) that senses a flow of water provided to the chamber (203, 603) from the water source (109, 509), and a temperature sensor (117b, 517d) that senses a temperature of humidified gas within the patient circuit (103, 503); and a controller (119, 519) having at least one processor configured to: receive, from the flow sensor (113, 513), flow data relating to water being provided to the chamber (203, 603) from the water source (109, 509), receive, from the temperature sensor (117b, 517d), temperature data relating to the temperature of the humidified gas within the patient circuit (103, 503), and characterized in that the at least one processor is further configured to: adjust a flow of water being provided to the chamber (203, 603) by the water source (109, 509) based on the flow data and temperature data. a water source (109, 509); a humidifier unit (107, 507) disposed on a patient circuit (103, 503) that provides gas to a patient, the humidifier unit (107, 507) located proximal to a patient interface (105, 505) of the patient circuit (103, 503), the humidifier unit (107, 507) comprising: a chamber (203, 603) that receives water from the water source (109, 509), a heat source (201, 601) disposed within the chamber (203, 603), a flow sensor (113, 513) that senses a flow of water provided to the chamber (203, 603) from the water source (109, 509), and a temperature sensor (117b, 517d) that senses a temperature of humidified gas within the patient circuit (103, 503); and a controller (119, 519) having at least one processor configured to: receive, from the flow sensor (113, 513), flow data relating to water being provided to the chamber (203, 603) from the water source (109, 509), receive, from the temperature sensor (117b, 517d), temperature data relating to the temperature of the humidified gas within the patient circuit (103, 503), and characterized in that the at least one processor is further configured to: adjust a flow of water being provided to the chamber (203, 603) by the water source (109, 509) based on the flow data and temperature data. a chamber (203, 603) that receives water from the water source (109, 509), a heat source (201, 601) disposed within the chamber (203, 603), a flow sensor (113, 513) that senses a flow of water provided to the chamber (203, 603) from the water source (109, 509), and a temperature sensor (117b, 517d) that senses a temperature of humidified gas within the patient circuit (103, 503); and a controller (119, 519) having at least one processor configured to: receive, from the flow sensor (113, 513), flow data relating to water being provided to the chamber (203, 603) from the water source (109, 509), receive, from the temperature sensor (117b, 517d), temperature data relating to the temperature of the humidified gas within the patient circuit (103, 503), and characterized in that the at least one processor is further configured to: adjust a flow of water being provided to the chamber (203, 603) by the water source (109, 509) based on the flow data and temperature data. receive, from the flow sensor (113, 513), flow data relating to water being provided to the chamber (203, 603) from the water source (109, 509), receive, from the temperature sensor (117b, 517d), temperature data relating to the temperature of the humidified gas within the patient circuit (103, 503), and characterized in that the at least one processor is further configured to: adjust a flow of water being provided to the chamber (203, 603) by the water source (109, 509) based on the flow data and temperature data. adjust a flow of water being provided to the chamber (203, 603) by the water source (109, 509) based on the flow data and temperature data.