Cooling Tower Shutdown
No
matter what type of cooling tower system you have, one thing is
certain - once October rolls around there is much less cooling
demand. In fact, some systems are not used at all in the winter.
Winter
is the time to perform the maintenance you couldn’t do in the summer
because the system was needed. What you do depends on whether or not
the tower is down for the winter.
Since
demand on the tower and condenser system is less in the winter, it’s
an ideal time to schedule a cleanup. Pressure wash all accumulated
dirt and biofouling from the inside of the tower, baffles and
distribution decks. If the condenser water is discolored or cloudy,
drain and purge the system using a product specifically designed for
this purpose.
If the
condenser system is not needed until
spring, it can be left dry over the winter. Temporary covers placed
over the openings in the tower prevent dust and debris from
entering. If the chilled water system is not to be circulated,
ensure that inhibitor concentrations are on the high side of normal
range.
For
systems that require year round condenser operation, the system
should be refilled and immediately charged with scale and corrosion
inhibitor according to published start-up procedure. Protect against
biological activity by adding appropriate microbiocides weekly.
HVAC
systems employing heat pumps and hydronic loops are needed all year
round. Since very little evaporation is taking place, scaling is not
a problem. It is vital, however, to ensure that the system is
protected against corrosion.
It is
not sufficient to just have the correct amount of corrosion
inhibitor in the system, it must also be circulated frequently to
ensure that fresh inhibitor is
supplied to all
parts of the system. This is because the concentration of inhibitor
decreases in areas where corrosion is active. To make up for this,
it is necessary to provide a fresh supply from the bulk liquid.
The
condenser pumps should be programmed to run at least five minutes
twice per day to provide circulation, or the pumps can be manually
run for this same period. Bear in mind that a static system is more
prone to the growth of anaerobic bacteria which could result in
serious pitting attack on system metals. Frequent circulation and
regular biocide additions are the best insurance against this type
of corrosion.
Even in
a mild climate one should be prepared for the possibility of a
freeze up which could damage valves, pipes and other outside
equipment. Either arrange for the system to circulate continuously
during these “cold snaps” or use insulation or heat tracing to
protect exposed equipment.
Remember that the pollination season for conifers may start in
January and there will be a lot of nutrients in the air. So whether
you have a year round or a seasonal system, make sure the tower
system has good microbiocide levels before and during the onset of
pollination.
Tower
and Condenser System Fall Checklist:
1.
Clean the system.
2.
Recharge with inhibitors and biocides (or leave dry)
3.
Circulate system at least twice per day.
4.
Protect from freezing, and
5.
Prepare for springtime pollination season.