A valve configured for use in a pressure support therapy system, the pressure support therapy system comprising a pressurized gas source, a supplemental gas source, and a subject interface with a heated tube, the valve comprising: an inlet cap, the inlet cap comprising a first electrical connector and a first flow path both configured to removably couple with the pressurized gas source, the first flow path configured to receive a pressurized flow of breathable gas from the pressurized gas source, the first electrical connector configured to receive electrical power from the pressurized gas source; a body coupled to the inlet cap, the body comprising: a channel configured to receive the pressurized flow of breathable gas from the first flow path; and a plunger biased to close the first flow path in the inlet cap when the pressurized flow of breathable gas is not provided by the pressurized gas source or is provided at a pressure that is below a predetermined pressure threshold, wherein closing the first flow path stops supplemental therapy gas from flowing through the inlet cap toward the pressurized gas source when the inlet cap is coupled to the pressurized gas source; and an outlet cap coupled to the body, the outlet cap including: a side orifice configured to receive the supplemental therapy gas from the supplemental gas source, and a second electrical connector electrically coupled with the first electrical connector and a second flow path coupled with the channel, the outlet cap configured to removably couple with the heated tube such that the second flow path conducts the pressurized flow of breathable gas and the supplemental therapy gas from the channel to the heated tube and the second electrical connector conducts the electrical power from the pressurized gas source to the heated tube when the outlet cap is coupled to the heated tube. an inlet cap, the inlet cap comprising a first electrical connector and a first flow path both configured to removably couple with the pressurized gas source, the first flow path configured to receive a pressurized flow of breathable gas from the pressurized gas source, the first electrical connector configured to receive electrical power from the pressurized gas source; a body coupled to the inlet cap, the body comprising: a channel configured to receive the pressurized flow of breathable gas from the first flow path; and a plunger biased to close the first flow path in the inlet cap when the pressurized flow of breathable gas is not provided by the pressurized gas source or is provided at a pressure that is below a predetermined pressure threshold, wherein closing the first flow path stops supplemental therapy gas from flowing through the inlet cap toward the pressurized gas source when the inlet cap is coupled to the pressurized gas source; and an outlet cap coupled to the body, the outlet cap including: a channel configured to receive the pressurized flow of breathable gas from the first flow path; and a plunger biased to close the first flow path in the inlet cap when the pressurized flow of breathable gas is not provided by the pressurized gas source or is provided at a pressure that is below a predetermined pressure threshold, wherein closing the first flow path stops supplemental therapy gas from flowing through the inlet cap toward the pressurized gas source when the inlet cap is coupled to the pressurized gas source; and an outlet cap coupled to the body, the outlet cap including: a side orifice configured to receive the supplemental therapy gas from the supplemental gas source, and a second electrical connector electrically coupled with the first electrical connector and a second flow path coupled with the channel, the outlet cap configured to removably couple with the heated tube such that the second flow path conducts the pressurized flow of breathable gas and the supplemental therapy gas from the channel to the heated tube and the second electrical connector conducts the electrical power from the pressurized gas source to the heated tube when the outlet cap is coupled to the heated tube.