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Midwest HVAC News
School Discovers
Cost-Cutting and Green Pool HVAC Dehumidifier Retrofit Strategy.
Stevenson H.S. saves $400,000 in retrofit costs, adds to its
green mission and serves as a retrofit role model for future
dehumidifier retrofits too large to remove.
 A
contractor's unique solution circumvented $400,000 in construction
costs during the retrofit of Lincolnshire, Ill.-based Adlai E.
Stevenson High School's indoor pool HVAC support equipment.
The innovative approach added to the suburban Chicago school
district's progressive green mission and also promises a
value-engineered resolution to the HVAC industry's impending
mechanical room dehumidifier replacement challenges.
The 3,950-student school's huge 40,000-square-foot natatorium, one
of only four 100-meter Olympic-sized pools in Illinois, was faced
with replacing two aging HVAC dehumidifiers requiring tens of
thousands of dollars annually in maintenance costs the last few
years. Installed when the natatorium was built in 1996, the removal
of the 15 (L) x 9 (W) x 8 (H)-foot and huge 15 (L) x 7 (W) x 8
(H)-foot heat recovery dehumidifiers would require upwards of
$400,000 in construction costs to tear open a wall or roof for their
removal, according to Mark Michelini, CPA, assistant superintendent
for business at School District 125.
Instead, the school district's longtime building automation and
energy services contractor Siemens Industry Inc. (SII), Mount
Prospect, Ill., and Michelini conceived the idea of leaving the
units in place, gutting them and commissioning dehumidifier
manufacturer, Seresco USA, Decatur, Ga., to factory-build entirely
new 64 and 40-ton dehumidifier components, coils, piping
inlet/outlet receptacles and control packages that would fit inside
the original manufacturer's steel shell configurations.
The revolutionary technique, which may someday become a standard
retrofit procedure as thousands of huge circa 1980's and 1990's
mechanical room dehumidifier lifecycles end, was also approved by
Stevenson's on-site building services contractor, Sodexo,
Gaithersburg, Md.; Bruce Svec, sales engineer at manufacturer's
representative, Imbert Corp., Niles, Ill.; and architect consultant
firm, Cannon Design, Chicago. The school district signed a
performance contract with SII to guarantee solving the dehumidifier
replacement challenge at a specified payback and cost.
Most of the challenge rested on Seresco USA however, which sent its
Vice President of Production, Jonathan Theriault, to assure the
critical measuring accuracy of the shells, components, various
piping connections, positions of inlets/outlets and the 25,000 and
15,000-cfm blowers, the latter which were retained to value-engineer
project costs. Matching the evaporator coils was the most difficult
challenge, according to Theriault.
Factory engineers then designed the entire configuration and
provided the installing contractor Team Mechanical--EMCOR Services,
Buffalo Grove, Ill., with 3-D, computer-modeled blueprints to
simplify on-site assembly and installation. The new
partially-assembled internal component packages arrived as a
compressor/refrigeration circuit skid, separate fully-dipped enamel
corrosion-proof evaporator, reheat and hot water coils, Command
Center/electrical control panels and dry coolers to minimize onsite
assembly. "All dehumidifier manufacturers have a similar physical
airflow sequence consisting of an evaporator coil, reheat coils,
compressor module/refrigeration circuit and fans, but fitting
equipment into another manufacturer's configuration and making it
easy for the contractor to install was a custom- engineering feat,"
said Svec, who helped coordinate the project between SII and Seresco.
Story
continues below ↓
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Instead of a
conventional 100-percent refrigerant dehumidifier, SII chose two
NP-Series Protocol models, which together substitute nearly
1,200 pounds of the original systems' refrigerant with
environmentally-friendly glycol that's PVC piped to rooftop dry
coolers 60 feet away for heat rejection. The units do use a
substantially reduced charge of approximately 400 pounds of
refrigerant R-410A, which doesn't have ozone-depleting chemicals
such as chlorine.
Michelini estimated the school could have postponed the
dehumidifier retrofit another five years, however the
refrigerant R-22-based units were developing leaks regularly and
increasing maintenance costs. Since R-22's chemical makeup
includes chlorine, a major leak and total refrigerant loss of
either unit would have damaged the environment. Furthermore,
replenishing a total charge of R-22 refrigerant would cost a
minimum of $20,000 just in refrigerant, because its prices are
skyrocketing as the U.S. Environmental Protection Agency (EPA)
continues an HCFC production phase-out that culminates with a
complete ban in 2020.
The strategy of reducing potential environmentally-damaging
refrigerants enhances the school district's aggressive green
mission, which typically includes annual carbon footprint
reductions aimed at cutting energy use by three to five percent
annually.
The 833,000-square foot school's ongoing progressive
sustainability efforts, such as high efficiency pumps,
condensing boilers, and various lighting and plumbing upgrades,
for example, have led to the district's Leadership in
Environmental and Energy Design (LEEDŽ) gold certification.
"Reducing refrigerant and chemical use in our building is part
of our sustainability mission," said Michelini.
Besides refrigerant reduction, the new dehumidifiers also save
15 to 20 percent more energy than their predecessors via scroll
compressors, direct drive fans and other comparably higher
efficiency components. Besides sustaining a 50-percent relative
humidity, the units use energy recovery to heat the pool water
to 80°F, and maintain an 82°F space temperature.
Another key to the
project's success was no down-time during the three-month retrofit.
One unit operated continually while the other was retrofitted. Thus,
the pool, which hosts important swimming events such as the Illinois
High School Water Polo Championships and the Midwest Zone Junior
Olympics, remained operational and open during its typical 16-hour
days.
Michelini suspects the
original dehumidifiers may have unknowingly experienced
slowly-degrading inefficiencies in between annual routine service
checkups. The new dehumidifiers won't run inefficienty because they
are each outfitted with a Command Center and Ethernet connection
that relays more than 100 operating parameters to Seresco's factory
engineers for daily review via Seresco's proprietary web-based
WebSentry.
An operating
inefficiency can be pinpointed and corrected the day it occurs,
rather than discovered months later during a service call.
Authorized personnel from the school district or Siemens can also
access the dehumidifiers via WebSentry 24/7 with a PC or a smart
phone to review operating conditions or emailed alarms. The Command
Center independently operates the dehumidifiers, but also reports
monitoring data to Siemens' Apogee building automation system. The
extensive information includes operational data log histories that
factory engineers use to assist local contractors troubleshoot and
repair service issues.
Although there was no ductwork modifications and new dehumidifiers
have a similar refrigeration capacity, Michelini said there's a
noticeable difference between the old and new technology in terms of
air comfort, especially during meets with in the 240-seat spectator
section.
Future replacements of
dehumidifiers too large to fit through mechanical room access doors
may someday all opt for the value-engineered approach of replacing
internal components and leaving the shells in place.
About Seresco: Seresco USA Inc., Decatur, Ga., is the U.S.
subsidiary of privately-owned Seresco Technologies Inc., which is
headquartered in Ottawa, Ontario. Seresco specializes in commercial
and residential indoor swimming pool dehumidifiers and other indoor
air quality HVAC equipment that's sold through a manufacturer's
representative network, and serviced and supported by
factory-trained service technicians. For more information, please
visit
www.serescodehumidifiers.com, email
sales@serescodehumidifiers.com or call (770) 457-3392.
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