Abstract: A heat exchanger unit comprises a plurality of heat exchangers of a construction in which a number of tubes are mounted on mounting plates, which additionally serve as manifolds, in a manner such that the tubes maintained in spaced relation while being twisted such that their axes conform to parts of helices.

Abstract: An environmental control system for controlling the environmental conditions in a swimming pool hall 1 comprises a heat pump having a multi-section evaporator 8, compressors 23a and 23b and a multi-section condensor 18.In the day-time, the dry bulb temperature in the pool hall is maintained by circulating space air through a duct 3 to the evaporator 8 where the latent heat is recovered from the moisture laden air. This heat is rejected via the condensor 18 either to the now drier recirculated air or fresh air from an inlet 13 or a mixture of air from the two sources. In a night mode of operation, circulation of space air through the duct 3 is prevented and instead it is recirculated via a direct recirculation duct 53 and is heated by the condensor 18, the heat used to do this being recovered from outside air inducted into the evaporator 8 via an inlet 50.

Abstract: An environmental control system has an evaporator section comprising an evaporator for extracting heat from (and dehumidifying) air destined for the controlled space or for exhaust--this air may be a controlled mixture of fresh and recycled air--and a chiller for extracting heat from a source such as well water and from a thermal store. The heat pump condenser section comprises a condenser for rejecting heat to air entering the space and a condenser receiver for rejecting heat to the store. The system includes a system controller (not shown) programmed to control operation in a manner tending to minimize the prime energy requirement.