Water-chilling systems for concrete production article in The Concrete Producer magazine, by Don Talend, brand storytelling, content management and demand generation expert. Construction industry

1. A
s summer approaches, bringing elevat-
ed ambient temperatures, producers
are beginning their “chill” routines.
Even in northern climates, many produc-
ers who had previously avoided chilling
water are finding that this practice results
in profitable service for contractors.
Manufacturers of water-chilling equip-
ment remind the producer to consider
five operational factors before purchasing
chilling- and chilled-water storage equip-
ment for the upcoming season.
1 Chilled-water volume needed.
Calculating an accurate required daily rate
of concrete is what matters, according to
Michael Lee, owner of Coldcrete, a Colo-
rado Springs, Colo.-based manufacturer of
concrete cooling equipment. Lee recom-
mends the producer size chilling equipment
based on average maximum daily require-
ments. But Lee also warns the producer to
be mindful of whether the schedule rou-
tinely includes large-volume back-to-back
production days. If 1000-cubic-yard days
are the exception rather than the rule, Lee
says, calculate the maximum rate for most
days and size the chiller and cold water
B Y D O N TA L E N D
ᮣ Consider
these 5 factors
when setting
up a water-
chilling system
COLD
WATER
How to Stay in
Proper sizing of
a water-chilling
system requires
a thorough
knowledge of
many facets of
the producer’s
entire operation.
PHOTOSCOURTESYPEARSONHEATINGSYSTEMS

2. storage tank accordingly. “On the other
hand, if a guy’s doing a paving job and he’s
doing 1000 yards day after day, he’s going
to need to size his chiller and his tank for
that 1000 yards.” In that case, he advises,
calculate the average concrete yardage
required over a few days.
2Material moisture content and
temperature. A plant’s daily chilled-water
requirement depends on the physical
properties of its cement, water, stone, and
sand. A thorough knowledge of these
properties can help the producer pinpoint
the required chiller size.
Jack Womack, president of American
GeoThermal, Murfreesboro, Tenn., asks
the producer to document the average
moisture content in an operation’s sand
and rock, which limits the amount of
water the producer can chill to achieve
the target temperature. “The more batch
water you’ve got, the more you can move
the temperature of the final mix,” says
Womack.
Delivered concrete temperature is
important, too. With many cement mills
pushed to the limits of their capacity,
cement storage time and thus cooling time
are often shorter than in the past. “A lot of
people are getting 150°, 160° F cement,
which has added to the demand for chilled
water at locations that have not needed it
in the past,” says Womack.
3Delivery time and distance. This
factor affects the level of fresh concrete
temperature reduction chilled water can
achieve. Keeping concrete cool is more
difficult than keeping it warm. For all
practical purposes, the delivery window
for cooled concrete is less than that for
concrete delivered during the winter. For
plant operators, delivery distance has a
bearing on the make and model of chiller
chosen. Available chillers normally pro-
duce water with a temperature of 35° to
40° F, although special measures such as
running an ethylene glycol/water mixture
through the heat exchanger can produce a
water temperature as low as 33° F.
Say the producer has a 90° F concrete
placement specification, and the well or
city water supply is 80° F. The chilling sys-
tem produces a typical water temperature
of 38° F for a 42° F water temperature
drop. The producer might get a 1° F con-
crete temperature decrease for each 6° F
the water temperature decreases, for a 7° F
decrease in concrete temperature. That
concrete temperature decrease is usually
enough to meet the placement spec for a
normal haul time. A water temperature of
35° F might allow the producer to make
longer hauls—and expand the company’s
service radius.
4Water source and disposal. The
producer’s water source affects the deci-
sion of whether to buy an air- or water-
cooled chiller, says Womack. Well-water
temperature is more consistent and lower
throughout the year, allowing the produc-
er to install a slightly less-expensive but
longer-lasting water-cooled unit.
However, the condenser water used
in a water-cooled chiller is often mixed
with coolant, so it must be disposed of and
not used in concrete. As a result, many
producers are choosing models with air-
cooled condensers.
5 Keeping supply constant. A
properly sized insulated tank, designed for
maximum concrete yardage under normal
circumstances or for average yardage when
big back-to-back days are the norm, takes
pressure off the chiller. If the chiller breaks
down, chilled water will still be available
throughout the day, Lee notes. More
importantly, a properly sized insulated
tank enables the chiller to produce chilled
water at a steady rate.
The key to steady production is an
automatic makeup system, Lee says.
This system automatically monitors
both the volume of water and its tem-
perature. It also not only keeps the tank
full, but it also maintains stored-water
temperature.
When the chilled water in the tank
is drawn down past a preset level, a float
switch sends a signal to a makeup valve.
Water is looped directly from the water
supply through the makeup valve and
into the chiller, keeping the water at a
consistent temperature. “At the end of
the day, the tank won’t be full, but you
Ample water storage and piping insulation are two keys to chilling system efficiency.

3. don’t have to do anything,” Lee says.
“The system just continues to make up
chilled water until the tank is full again
during the night, and then the float
switch will shut off the chiller automat-
ically. It only costs a couple of hundred
bucks for all this stuff, and just the guy’s
time paying attention to it is worth
more than that.”
To get their highest chilled-water
production rates, the producer should pipe
makeup water into the chilling system,
not directly into the tank, Lee adds. This
practice better controls the stored-water
temperature so the plant makes full use of
equipment capacity.
Make sure you don’t overlook tank
insulation either, notes Marc Mariano, oper-
ations manager at Pearson Heating Systems,
Stevensville, Md., a manufacturer of both
water-chilling and water-heating equip-
ment. “Whether the customer is purchas-
ing an insulated storage tank or insulating
an existing one, it should either be cov-
ered with a vapor barrier or insulated with
closed cell insulation,” he says. “This pre-
vents the tank from building up condensa-
tion, or sweating, which lowers the insula-
tion efficiency.”
Mariano also stresses the importance
of insulating with closed cell material the
circulation pipes and the pipes leading
from the tank to the plant.
Maintenance of an air-cooled chiller
is perhaps the most important factor in
keeping water temperature constant,
Mariano adds. “The condenser coils have
a tendency to get covered with dirt and
dust,” he says. “It’s very important to keep
these coils free of dust, because that lowers
the efficiency of the unit. When cleaning
these coils, use only compressed air.
Spraying the coils with water can perma-
nently clog them.”
For more information about custom sizing a
water-chilling system to your operation, circle the
manufacturers’ corresponding numbers on the
reader service card.
American GeoThermal 2
Coldcrete 3
Pearson Heating Systems 4
Publication #T01E043
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