relay can only accompl is h t his if the relay has been add ed to the cooling tower te m per a ture
controller. The
TOWER FAN RELAY
is turned on whenever the
CONDENSER WATER PUMP
is running, flow is verif ied, and the differenc e bet ween cooler and condens e r pressure is more
than 45 psid (310 kPad) (30 psid [207 kPad] for HFC-1 34a ) or entering condense r water
temperature is greate r than 85 F (29 C). The
TOWER FAN RELAY
is deenergized when the
condenser pump is off, f low is lost, the evaporato r re fri gerant temperature is less than the
override temperat ur e, or the differential pre ssure is less than 40 psid ( 279 kPad) (28 psid [193
kPad] for HFC-134a) and entering condensing wa ter is less than 80 F (27 C).
IMPORTANT: A field-su p plied water temperatu re control system for con denser water
should be installed. The system should maintain the leaving condenser water tempera-
ture at a temperature tha t is 20° F (11° C) above the leav ing chilled water temp era ture.
CAUTION CAUTION
!
The tower-fan rel ay control is not a sub stitute for a condens er water temperature
control. When used with a Water Temperature Contr ol system, the tower fan
relay control can be used to help prevent low condenser water temperatures.