Heating and cooling system

Claim 1

In an air-conditioning system for heating and cooling multiple zone building units, which includes a source of supply of heated water, a source of supply of chilled water, a single pipe closed distribution system in each individual controlled area connecting said sources of supply for conducting heated and chilled water through each said closed distribution system, heat exchange means in each said closed distribution system for each individual controlled area; a single thermostat in each controlled area and means automatically controlled by the thermostat in each individual controlled area for conducting heated or chilled water through the single pipe closed distribution system in its area; and means for returning said heated and chilled water each to its respective source; said means controlled by said thermostat including a pair of three-way bypass valves each said bypass valve arranged at oppoSite ends of each said single pipe closed distribution system, the first said bypass valve adjacent said source of supply of heated water, the second said bypass valve adjacent the source of supply of chilled water each said bypass valve in normal nonactuated position connecting said single pipe closed distribution system to the respective said source of supply and in actuated position the first said bypass valve connecting said single pipe closed distribution system with said means for returning chilled water to its source and the second said bypass valve connecting said single pipe closed distribution system with said means for returning heated water to its source; a pair of check valves, the first said check valve arranged between the first said bypass valve and the said source of supply of heated water, the second said check valve arranged between the second said bypass valve and the said source of supply of cooled water, both said check valves arranged to permit flow of water from the respective said source of supply to the respective said bypass valve but not in the opposite direction; said thermostat separately and individually actuating one said bypass valve or the other, the first said bypass valve being actuated when passage of chilled water through said single pipe closed distribution system is called for and the second said bypass valve being actuated when passage of heated water through said single pipe closed distribution system is called for; whereby heated or chilled water is conducted through said single pipe closed distribution system in opposite directions as called for by said thermostat.