Practical air treatment cycles

The majority of air-conditioned buildings are offices or are used for similar indoor activities, and are occupied intermittently. The heating system must bring them up to comfortable working conditions by the time work is due to start, so the heating must come into operation earlier to warm up the building. 

A large part of the heating load when operating in daytime will be for fresh or outside air, which is not needed before occupation, and the heat-up time will be reduced if the fresh air supply can remain inoperative for this time. 

The required warm-up time will vary with ambient conditions, being longer in cold weather and least in warm. Optimum-start controllers are now in general use which are programmed for the building warm-up characteristics and sense the inside and ambient conditions. They then transduce the required start-up period and set the heating plant going only when needed. This, and the previous scheme, will save fuel. 

The addition of moisture to the winter air in the UK is not usually necessary, except for systems using all outside air, or where persons with severe respiratory trouble are accommodated. With a winter 

Air washers require water treatment and bleed-off, since they concentrate salts in the tank. Steam will be free from such impurities, but the boiler will need attention to remove accumulations of hardness. 

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