在大多数装置中，热泵可以提供热量。回收系统或多或少遵循了传统的循环。在许多情况下，增加的交换设备会增加恢复或传递功能的第一成本。在热回收应用领域的30年中，作者开发了完全不同的循环。在许多情况下，这些差异旨在提高热泵热量回收的效率，但它们也对空调程序产生了有利的影响。在所有情况下，电力和整体运营费用都有所降低，在某些情况下，加热-冷却功能的部分（如果不是全部）第一成本也有所降低。在最早的应用中，人们认识到闭合接近线圈的重要性。这种近距离接触扩展到了冷却塔- -热交换功能、冷凝器和水冷却器。在接近的情况下，全年的回水温度基本相同。这一特性反过来又引出了一个共用的回流管，并使高效、可行的三管系统（热供、冷供和共用回流）成为可能。宽量程导致更小的管道、更少的绝缘、更小的阀门和控制装置。最重要的是，设备尺寸减小了。通过混合用于加热和回流的回水和热水以及用于冷却的冷水来进行控制，是一种简单且廉价的方法，可以消除因泵送量可变而产生的问题。近距离的方法使热泵的开发成为可能，以降低夏季制冷的成本，并与压缩系统相结合。 多个冷凝器和水冷却器串联，可在降低运行成本的情况下实现高冷凝温度和低冷冻水冷却温度。冷凝水温度较高的原因是，在液体冷却器冷凝或冷却塔中使用低湿度的内部排气，通过水板式热交换接近水。较低的冷冻水温度导致回风湿度较低，使得换热器出水的温度低于大范围盘管的直接回风温度。实际上，这允许部分夏季内部热量直接排放到流体冷却器或通过热交换器排放到冷却塔，从而降低冷水机组的容量。这种夏季热泵的使用尤其适合储罐储存，以减少夏季需求费用等- 称为棘轮费用（夏季高峰需求影响全年高峰需求）。水的广泛范围大大缩小了水箱的尺寸。可能最重要的是热平衡控制，这使得消除冬季省煤器循环成为可能，从而去除可回收用于冬季热泵运行的可用和有价值的热量。与没有分段的情况相比，分段允许使用更高的热水进行加热。所有的好处结合在一起才是最有价值的，尤其是在降低初期成本方面。单位:I-PCITION:研讨会，ASHRAE交易，1988年，第94卷，pt。2、渥太华

In most installations, heat pump heat. recovery systems have followed more or less conventional cycles. In many cases, added exchange apparatus resulted in added first cost for the recovery or transfer functions.During 30 years in the field of heat recovery applications, entirely different cycles were developed by the author. In many cases, the differences were intended to increase the efficiency of the heat pump’s heat recovery, but they also favorably affected air-conditioning procedures. In all cases, power and overall operating expense were reduced, and in some cases, first cost was reduced for part, if not all, of the heating - cooling functions.The importance of close approach coils was recognized in the earliest applications. This close approach was expanded to the cooling tower -- heat exchange functions, condensers, and water coolers. With close approaches, the return water is substantially the same temperature all year. This feature led, in turn, to a common return pipe and made possible an efficient and workable three-pipe system (hot supply, cold supply, and common return). Wide ranges result in smaller as well as fewer pipes, less insulation, smaller valves and controls. Most important, the equipment sizes were reduced.Control by mixing return and hot water for heating and return and cold water for cooling is a simple and inexpensive way to eliminate problems resulting from variable pumping quantities.Close approaches made possible the development of the heat pump for less expensive summer cooling in conjunction with compression system staging. Multiple condensers and water coolers in series permit high condensing and low chilled-water cooling temperatures at reduced operating costs.The higher condensing water temperature is made possible by the use of low-humidity inside exhaust air for either fluid cooler condensing or cooling towers with close approach water through water plate type heat exchange.The lower chilled-water temperatures result in low-humidity return air that permits water off the exchanger to be lower in tempera~re thlan the direct return water from wide-range coils. In effect, this allows part of the summer internal heat to be discharged directly to the fluid cooler or through a heat exchangerto the cooling tower, thus reducing the water chiller capacity.This use of a summer heat pump is particularly desirable with tank storage to reduce summer demand charges and so-called ratchet charges (where peak summer demand affects year-round peak demand). The water wide range greatly reduces the tank size.Probably most important is the heat balance control, which made possible the elimination of the winter economizer cycle removing usable and valuable heat that could be recycled for winter heat pump operation. The staging permits higher hot water for heating than is available without staging.It is all the benefits in combination that is most valuable, especially in reducing first costs.Units: I-P