User manual

Fan cycling limits:

Considering the normal fan and motor sizes utilized on MH Fluid

Coolers, anticipate that approximately4 to 5 starts perhour are

allowable.

If your ﬂuid cooler is equipped with a two-speed motor(s), you will enjoy

greater opportunity for process temperature control. When the process

ﬂuid temperature becomes too cold, switching the fan to half-speed will

cause the cold process ﬂuid temperature to rise—stabilizing at a tempera-

ture a few degrees higher than before. With a further reduction in ﬂuid

temperature, the fan may be cycled alternately from half-speed to off.

Donotstartthemotormorethanfourtovetimesperhour(each

lowspeedstartandeachhighspeedstartcountasonestart).

For greater insight on process ﬂuid temperature control, please read

“Cooling Tower Energy and its Management”, Technical Report

#H-001-A, available at spxcooling.com.

Pump cycling limits: Marley does not recommend the recirculation

water pump(s) be cycled to control process ﬂuid temperature. It is recom-

mended that while process ﬂuid is being circulated through the coil the

ﬂuid cooler recirculation water system always be in operation. Cycling

the recirculation water pump(s) may lead to premature scaling of the coil

surface.

Dampers: If equipped, the positive closure damper system is designed

to help prevent heat loss from the coil due to air movement caused by

convection or wind conditions when both the fan and pump are off.

Upon start-up of the ﬂuid cooler fans, the damper actuator is energized

and rotates the damper assembly blades open. The actuator should be

wired into the control circuitry of the fan motor. Upon system shutdown

the damper actuator is de-energized and the spring return actuator returns

the damper blades to the closed position.

Ifthedampersareequippedwithanautomaticelectricactuator,

the actuator electric motor controller will include a 115-volt AC

space heater in accordance with the SPX Cooling speciﬁcation.

The space heater is to be energized at all times whether actuator

Operation

Note