Marley Marley Class F400, User Manual

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6
Caution
operation will be enhanced if you read “Operating Cooling Towers in
Freezing Weather” Marley Technical Report #H-003.
Ice forming characteristics on any given cooling tower will vary, depending on
velocity and direction of wind, circulating water rate, and heat load. Excessive
ice formation may be controlled by regulating air and water flow through the
tower by one or more of the following procedures:
1–Shut the fan down. This reduces the cooling air rate to a minimum and in-
creases the quantity of warm water at the air inlet to a maximum. However,
normal “fan off” operation causes reverse air flow by aspiration and may
cause water blowout and therefore must be done with caution and moni-
toring. For automatic operation, a timer switch can be provided to shut the
fan down for a few minutes each hour.
2–When a cooling tower has two-speed motors, operate the fans at half speed
forward. This reduces the cooling air rate (heat transfer) and increases the
quantity of warm water at the air inlet.
3–With no heat load on the circulating water, icing cannot be controlled. Towers
must not be operated with reduced water rate and/or no heat load during
freezing weather. If a bypass directly into the cold water basin is used, all
water must be bypassed.
Reverse operation of fans is not recommended . See “Fan Drive”
for fan speed change precautions.
INTERMITTENT OPERATION –When the unit is operated intermittently dur-
ing winter weather, it is necessary that the water be drained from the tower
piping to insure protection against freezing and possible rupture.
Tower Maintenance
Always shut off electrical power to the tower fan motor prior to
performing any inspections that may involve physical contact with
the mechanical or electrical equipment in or on the tower. Lock out
and tag out any electrical switches to prevent others from turning
the power back on. Service personnel must wear proper personal
protective clothing and equipment.
Well-maintained equipment gives the best operating results and the least
maintenance cost. SPX recommends setting up a regular inspection schedule
to insure effective, safe operation of the cooling tower. Use the schedule on
page 16 to obtain continuously good performance with the least tower main-
Warning