valve. High pressure opens the valve, allowing a
greater flow of water; low pressure throttles the flow.
Use of such a valve provides for a more economical use
of water for condensing. Figure 7-33 shows a typical
water-regulating valve. When condenser water is
supplied by a cooling tower, water-regulating valves
are not customarily used because the cooling tower fan
Figure 7-33.Water-regulating valve.
and circulating pump are wired into the compressor
motor control circuit.
The step controller contains a shaft upon which is
mounted a series of cams. Rotation of the cams, in
turn, operates electrical switches. Through adjustment
of the cams on the shaft, the temperature at which each
switch is to close and open (differential) is established.
In addition, the switches may be adjusted to operate in
almost any sequence (fig. 7-34).
Table Z of appendix II is a troubleshooting chart
generally applicable to all types of air conditioners.
Most manufacturers include more detailed and specific
information in publications pertaining to their units. If
you find that there is no manual with the unit when it is
unpacked, write to the manufacturer and request one as
soon as possible.
How are cooling towers classified?
Q22. A wind velocity of 8 mph is generally used to
design natural draft cooling towers. True /False
Counter flow, parallel flow, and cross flow are
types of what class of cooling tower?
Figure 7-34.Step controller and pressure-sensor configuration. (A) Step controller with modulating motor, single-pole
double-throw mini switches, and mouse trap relay assembly; (B) Pressure sensor that controls the step controller.