Cooling your plant at a lower cost
any plant owners are
turning to refrigerated air conditioning to cool their plants
and customer service areas because of the myth that the
“other option” does not work in humid environments.
Let’s face it, refrigerated air is
the ultimate answer to maximum comfort, but for a drycleaning
and laundry plant that generates a great amount of heat, it
would require an excessive amount of tonnage to really do the
job right.
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I asked the local gas and electric company
for an operation cost estimate, and the cost to operate the
unit, not considering the excess usage for a hot drycleaning
and laundry plant, was approximately $1.25 per hour. This
figure was in addition to the cost for electricity to run the
equipment, lights, etc. This was back in 1971.
Most refrigeration cooling units require a
booster blower to produce the turbulence needed for dispersing
the air over large areas and to give comfort while spot cooling
of the individual work areas. It is not always practical to
blow the refrigerated air directly over the individual worker,
who may be constantly moving out of the chill and entering the
heat as required by the type of production unit being operated.
Why do we need to air cool the plant on
torrid days? The answer is simple: To increase production,
reduce absenteeism and enhance morale via a comfortable
environment. No one wants to work in a hot, stuffy environment.
Our customers do not wish to visit a store that is
uncomfortably hot and with the front door open to let in the
hot air from outside. I have seen CSRs with shiny and greasy
foreheads and washed-out looks on their faces from the heat and
discomfort of a store with no air cooling. FANS DO NOT DO IT!
Although the current refrigeration units
have more efficient technology, the cost to purchase, install
and operate them is still considered to be much higher than the
“other option.” This option is known as
“evaporative cooling” and sometimes the unit is
called a “swamp cooler.” This method of cooling is
not new. Manufacturing plants, restaurant kitchens, automobile
service departments, large warehouses, etc., use evaporative
cooling because of its simplicity for maintenance and low
investment and operation cost.
My own production plant of more than
30,000 square feet and my package plants were all cooled with
evaporative cooling units. I cannot begin to describe the
comfort and employee efficiency derived from this system of
cooling.
What is evaporative cooling?
It is a process in which temperatures are
lowered by evaporation of water. The handbook of the American
Society of Heating, Refrigeration and Air Conditioning
Engineers (ASHRACE) states: “Evaporative cooling,
properly applied, is the most practical means available today
to improve products (grown and manufactured) by successfully
reducing the dry bulb temperatures and/or controlling the
humidity.”
Of special note is the fact that it is
applicable in either humid or dry climates.
How does it work?
The basic principle of evaporative cooling
centers on removing heat from the air with water. Another name
for evaporative cooling is “washed air.”
In operation, outside air is drawn into
the unit passing through filters which are saturated with
water. The filters, or pads, are made wet by a small pump which
draws water from a small trough, or tank, and sprays it over
the filter pads.
Some units pump the water through a
dispersing fitting which continuously pours a steady stream of
water at the top of each filter pad, through a channel top, so
the filter pad is saturated at both ends and in the center. The
strong fan then discharges the cooled and washed air into the
plant.
Evaporative coolers work similar to
one’s sitting on the beach with the sun shining on the
water causing evaporation.
The breeze picks up evaporation, and you
get the cooled breeze blowing over you.
Therefore, evaporative cooling is the most
practical and economical method of providing comfortable
working environments for employees involved in production
processes using heat-generating equipment. The technique is
also applicable to cooling areas where big freight doors must
be open most of the time, and to providing make-up air for
production processes that require constant exhaust, such as
paint booths.
Two types of systems
Application of evaporative cooling is
broken into two basic systems: “spot cooling” and
“area cooling.” As the name implies, spot cooling
utilizes a duct system with outlet grilles to cool specific
work stations.
Area cooling, on the other hand, would be
used where workers are constantly moving about, such as in a
warehouse, a drycleaning plant’s assembly area, a coin-op
laundry, a customer service area, etc. Employee comfort is
greatest when airflow is directed at the waistline.
Savings over refrigerated air unit
How much can you save using evaporative
cooling rather than refrigerated air conditioning? A
well-designed evaporative cooling system, operated properly for
efficiency, compared to a refrigerated air cooling system, was
cost-studied by one of the most popular manufacturers and
designers of evaporative cooling as follows:
• Initial cost: 30 percent lower.
• Operating cost: 70 percent lower.
• Maintenance cost: 70 percent lower.
Types of design and installation
There are two types and installations of
these units: “side discharge” and “down
draft.” On the side discharge models, it is usually set
on a stand alongside the building ducting through the wall into
the room. A grill with a diffuser is installed (usually a
four-way).
On the down draft model, it is installed
on the roof where the sun increases the rate of evaporation. A
curb top roof jack and duct running down into the roof with a
diffuser (usually a four-way) sends in the cooled, clean air.
Maintenance of the unit
Maintenance of an evaporative cooling
system is both quick and easy. Service can be performed by
someone in your plant rather than by a refrigeration mechanic.
Total servicing for a complete season
takes about one hour per unit. In the once-per-year
maintenance, the water tank is cleaned. If any rusting has
occurred, those areas on the interior of the pan should be
sanded and repaired with a good rust-resistant paint.
The tank should then be filled with water
and the float valves adjusted to maintain the proper water
level. Additionally, all filter pads should be replaced at this
time.
Filter pads are manufactured from a
variety of materials, some being of impregnated redwood fibers
which normally are replaced yearly. Others use a synthetic
material which gives additional life but not quite the
freshness of air.
Some units use a filter pad on only one
side with a slinger for the water in that it constantly slings
a wall of water for the air to pass through.
One manufacturer draws outside air through
three sets of filter pads and a water spray system. An inlet
filter cleans incoming air and eliminates water spray onto the
roof. The water spray cools the air and washes any remaining
dirt into the water pan. Then the air passes through another
filter pad which is constantly wetted and washed down by the
water spray. The third filter is dry and prevents entrained
moisture from being drawn into the blower section.
Another manufacturer includes a filter and
pump system on two ends of the unit. This eliminates water in
the pan area of the fan chamber. The wetted units on either end
of the assembly are equipped with a media type of filter pad
which lasts a very long time.
Starting the spray pump will allow visual
assurance that the entire cooling surface is being covered by
the water spray. The bearings on the blower should be oiled.
Belt tension should be checked and increased if necessary.
At the end of the early fall season, the
water tank and all roof-top piping should be drained to avoid
freezing and damage during bitter cold winter months.
Most evaporative coolers are equipped with
a variable two-belt sheave on the motor. In adjusting these
sheaves for different speeds, extreme care should be taken to
have each sheave precisely the same width apart so both V-belts
are traveling the same speed. If not, one belt will pull
against the other causing an overload on the motor.
After the unit has been installed for 30
days, it will usually be necessary to tighten the drive belts
since they have a tendency to stretch during the first
month’s use.
My experience with two-speed motors on
evaporative coolers has been bad. Motor failure on two-speed
units is quite common (as attested to by several installers and
engineers).
If a lower air volume is needed at
different times, you could install a damper in the ducting that
could be manually closed or opened. The cooling unit will not
be affected by the air restriction as long as it is not
completely closed in a single duct installation.
Use of exhaust fans for proper air changes
Exhaust fans can force the stale plant air
outside. However, if they exhaust 100 percent of the air forced
into the plant, a slight vacuum may develop within the plant,
causing dirty, dusty air to be drawn in and around the windows
and doors. To avoid this condition, it is advisable to provide
exhaust facilities for no more than 90 percent of the air
brought into the plant.
For example: if using a 15,000 CFM
evaporative cooling unit, the exhaust fan system should not
exhaust more than 13,500 CFM of the air.
If exhaust fans are not feasible or cannot
be installed because of building location, escape for the
incoming air can be through a set of louvers in one rear wall.
The volume of incoming air actually forces the louvers open,
allowing the air to escape.
When installing the inside ducting, it
should be designed with large sweeping and rounded turns, not
90 degree square corners.
Windows and doors should be closed most of
the time, and should be opened only as needed. Remember, an
exhaust fan will pull out air from the nearest opening, so do
not install an exhaust fan close to an opened window or door.
The exhaust fan should be used to remove heat from inside the
plant, not to bring in heat from the outside. The cooled,
washed air should be brought in from the outside only.
With close management and perseverance,
together with proper maintenance and operation of the
evaporative cooling units, combined with proper sizing of the
unit, your plant can be the model of comfort for both you and
your employees.
Note: My spotting video, “The
Caplan Method of Stain Removal,” which includes my
comprehensive text and handy spotting board reference available
in English, Spanish and Korean (video only in Korean) from the
Golomb Group, c/o Dennis McCrory, 7664 Plaza Court,
Willowbrook, IL 60521, phone (800) 679-5856. A lecture and
demonstration are presented similar to my classes over the
years at IFI and SDA. This video and text are ideal for
training inexperienced spotters as well as a good review for
experienced spotters. Digesting with enzymes, bleaching,
oxidized oil stains and caramelized sugar stains are discussed
and demonstrated. An article on “Removing Spots in the
Cleaning Machine” and an article on “How to
Increase Production in the Spotting Department” are
included in the comprehensive text book.
Also available from the Golomb Group, in
English and Spanish, is my video on step-by-step shirt
finishing which includes my comprehensive text in loose-leaf
form outlining each procedure for single-operator and
two-operator cabinet shirt unit using a cabinet sleeve press.
Proper forming of the collar using heated collar formers is
demonstrated. Each lay is demonstrated for top quality with
very little effort by the operators. Attractive detailing and
packaging of the hangered shirt, padding, steam pressures and
timing are all discussed. A unique wash formula for whiter
whites and brighter colors and removal of grease and body oils
is included in the loose-leaf text book.
My experience with shirts spans over 55
years with US Army as a principal laundry and dry-cleaning
concessionaire at Ft. Meade, MD, where average shirt volume was
approximately 10,000 per day. We were constantly
“sampled” for excellent quality in both finishing
and washing in laundry and drycleaning and in tailoring. We
operated our own 40,000-sq.-ft. plant for over 35 years.
Stan Caplan has over 35 years experience
in his own high volume dry-cleaning, laundry and tailoring
plant and two package plants with adjoining coin-operated
laundry and drycleaning. Stan is the former chief instructor at
the International Fabricare Institute, the Southwest
Drycleaners Association and various other trade
association-sponsored schools throughout the US and courses in
Canada, Mexico, South Africa, Singapore and Hong Kong. Stan
offers consulting, training and engineering services in all
areas from customer service area to the boiler room since 1981.
His complete system withtotal quality management will produce
maximum efficiency, economy and product excellent quality. Stan
can be reached at 3601 Clarks Lane, Suite 307, Baltimore, MD
21215-2731, phone/fax (410) 358-0870. His e-mail address is stancap100@aol.com.