21
Cold Weather Operation
EVAPCOcounterowevaporativecoolingequipmentiswellsuitedtooperateincoldweather
conditions.Thecounterowcoolingtowerdesignencasestheheattransfermedia(ll)completely
and protects it from the outside elements such as wind which can cause freezing in the unit.
When the evaporative cooling unit is going to be used during cold weather conditions, several items need
to be considered. These include: unit layout; unit piping; unit accessories and capacity control of the units.
Unit Layout
Adequateunobstructedairowmustbeprovidedforboththeintakeanddischargefromtheunit.
It is imperative that the equipment minimize the risk of recirculation. Recirculation can result in
condensation freezing the inlet louvers, fans and fan screens. The buildup of ice on these areas
canadverselyaffectairowandinmoreseverecases,leadtofailureofthesecomponents.
Prevailing winds can create icing conditions on the inlet louvers and fan screens adversely
affectingairowtotheunit.
For additional information on unit layout, please refer to EVAPCO’s Equipment Layout Manual -
Bulletin 311.
Unit Piping
All external piping (water make up lines, equalizers, riser piping) that is not drained needs to be heat
tracedandinsulatedtomakecertainitdoesnotfreeze.Allpipingshouldbettedwithdrainvalves
to avoid dead legs which can lead to Legionella contamination. System piping accessories (make
up valves, control valves, water circulation pumps and water level control packages) also require
heat tracing and insulation. If any of these items are not properly heat traced and insulated, the
ensuing ice formation may result in component failure and cause a shutdown of the cooling unit.
The use of a bypass should also be considered. Typically, winter loads are less than peak
summer loads. When this is the case, a cooling tower bypass needs to be incorporated into
the system design to allow water to “bypass” the tower’s water distribution system as a means
of capacity control. EVAPCO recommends that the cooling tower bypass be installed in the
condenser water piping system. Bypasses installed in this manner require a section of piping
between the condenser water supply and return leading to and from the cooling tower. Never
use a partial bypass during cold weather operation. Reducedwaterowcanresultinuneven
waterowovertheheattransfermedia(ll),whichcancauseiceformation.
Pleasenote:bypassesshouldbeperiodicallyushedtominimizestagnantwaterconditions,
unless the bypass is piped directly into the unit’s cold water basin.
Unit Accessories
The appropriate accessories to prevent or minimize ice formation during cold weather operation
are relatively simple and inexpensive. These accessories include cold water basin heaters, the use
of a remote sump, electric water level control and vibration cut out switches. Each of these optional
accessories ensure that the cooling tower will function properly during cold weather operation.
Cold Water Basin Heaters
Optional basin heaters can be furnished with the cooling tower to prevent the water from
freezing in the basin when the unit is idle during low ambient conditions. The basin heaters
are designed to maintain 5° C basin water temperature at -18° C, -29° C and -40° C ambient
temperature. The heaters are only energized when the condenser water pumps are off and
nowaterisowingoverthetower.Aslongasthereisaheatloadandwaterisowingover
the tower, the heaters do not need to operate.
To Next Page
Loading...
Need help?
General
