In which warm or cold air from the central station is delivered

Official title: {in which warm or cold air from the central station is delivered via individual pipes to mixing chambers in the space to be treated, the cold air/warm air ratio being controlled by a thermostat in the space concerned, i.e. so-called Dual-duct System}

F24F3/0522 (In which warm or cold air from the central station is delivered) appears on 15 US grants and 2 published applications in this corpus.