All Water System & Air-Water System

In an All - Water System water (the controllable fluid) is circulated to the space. Thus a special type of terminal unit (Figure below) is required in the space.

Essentially each space requires a small air handling unit consisting of a coil, a fan, and a filter.

Return air (Figure 26) is drawn into the unit by the suction of the fan. The air is then filtered and passes on to the suction of the fan.

From this point the same thing happens what has happened in the All Air.

So what has happened in All Air at this stage.

Heat removed from the space (Figure above) is then transferred to the refrigeration equipment thru a network of chilled water pipes. Heat rejection equipment then transfers the heat from the refrigeration equipment to the outdoors.

The only thing lacking is proper odor removal, because an All - Water System circulates water, not air.

Air - Water System

The lack of odor removal leads us to the third basic system - the Air-Water System.

A separate air system (Figure below) is provided to supply fresh ventilation air to the space.