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August/September 2015
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Navien Provides Schools with
DHW Systems to Weather the Storm
Product Focus: Water Heaters
Change Service Requested
Southern Trade Publications
P.O. Box 7344
Greensboro, NC 27417
PHC
Cover Story
Navien Provides Schools with
DHW Systems to Weather the Storm
Even in times of peace and plenty,
building and occupying a modern
school is an endeavor for any community. Building three at once, even with ample years of planning, is a challenge of
monolithic proportions. Doing so amidst
utter chaos and tragedy in the fallout of a
natural disaster is unfathomable.
That’s just what the rapidly-growing
town of Moore, OK did immediately on
the heels of the F5 tornado that claimed
lives and ravaged the town in the spring
of 2013. And they did it in nine months.
“The town reeled in shock for a few
days,” said David Elliott, the school district’s plumbing foreman. “Aid came
pouring in from around the country,
and as soon as could be expected, demo
crews were cleaning up the rubble that
once was Plaza Towers Elementary and
Briarwood Elementary School.”
The district’s administration building had been strafed by the twister as
well, completely knocking out the entire
school server. A third school, Highlands
East, was also scathed. The mechanical
room had literally been sucked right off
of the building; heavy components flung
some untold distance to join the miles of
garbage and flat wasteland that had once
been 13,000 beautiful suburban homes.
The district planned to swiftly rebuild
Plaza Towers Elementary (bottom left) was one of the schools demolished by the F5 tornado that tore
through Moore, OK, in May of 2013. South Lake Elementary (top) shares a very similar blueprint
with Plaza Towers, an advantage during the fast construction schedule. Briarwood Elementary
(bottom right) was also destroyed by the 2013 tornado and rebuilt along with the other two schools.
10 Southern Plumbing•Heating•Cooling Magazine
the two demolished schools and continue with existing plans to construct
a third; Southlake Elementary. Plus,
countless other public buildings needed repair. Every tradesman in town and
many from neighboring states felt the
impact close to home. They knew from
the onset that it would take long hours
and a tenacious mindset.
Dedication and Know-How
“For nine months our guys worked
60-hour weeks to install plumbing and
HVAC systems at various buildings in
the district,” said Randy Hunter, owner of Hunter Mechanical in Oklahoma
City. “Everyone had a good attitude
about the projects, but going that hard
for that long really wore us down.”
With 40 employees, Hunter covers
most of Oklahoma. The company’s
main focus is commercial plumbing and
HVAC, but high-end custom homes account for roughly 10 percent of their
installs. The big homes allow them to
apply their core skill set and experience with high-efficiency equipment;
web-enabled controls, radiant in-floor
heat, tankless water heater systems and
ground-source heat pumps.
That skill set was vital in the twister’s
aftermath, as well. Moore needed three
new schools, fast, but couldn’t afford to
sacrifice efficiency, sustainability and
longevity in the name of expediency.
The district could have used 10 Hunter
Mechanicals in 2013.
“You’ve heard the saying that goes
roughly, ‘You want it done well, quickly
and affordably. Pick two,’” said Hunter.
“That’s kind of where we were, but the
district had no choice but to demand
PHC
Cover Story
Superior Systems
Randy Hunter (above top), owner of Hunter Mechanical, routinely uses Navien’s NPE line of water
heaters for schools, restaurants, multi-family units and hi-end residential. Four Navien NPE 240A
tankless water heaters cascade their operation in order to provide the exact temperature and water
volume the school’s big commercial kitchen needs. The four units are pictured here (bottom) with
David Elliott, the school district’s plumbing foreman, who is in charge of all plumbing systems in the
school district, including nearly 50 Navien tankless water heaters.
all three. Due to the nature of the situation, everyone involved anted up and
delivered. Not just my guys, but all the
trades.”
The key to overcoming countless obstacles was working harder, working
smarter and using the best products for
the application. For instance, two of the
schools feature a very similar blueprint;
a big advantage to the general contractor and trades involved.
When it came time to install plumbing components, simple, yet superior
systems cut down on install time.
Instead of one central mechanical
room housing all DHW production
equipment with hot water lines running
throughout the building, tankless water
heaters were installed in close proximity to all the main points of use; kitchen,
janitorial closets and bathrooms.
There are 16 Navien NPE-240 units
throughout Plaza Towers Elementary,
and the other schools in the district
use the same approach. Four serve the
kitchen, while the others are paired together in smaller mechanical spaces,
primarily in closets between the boys
and girls bathrooms.
Above the drop ceilings, the two-inch
PVC venting ties into a common pipe so
that only two penetrations are made in
the roof, saving more install time. The
units’ firing rates cascade in order to
provide only the amount of hot water
needed, not wasting any energy. The
NPE-240A unit features integrated controls that allow the units to communicate. Up to 16 can be cascaded and common vented for maximum capacity and
efficiency.
“You simply click a communication
cable from unit to unit, like a phone jack,
press a few programming buttons on
each unit and you’re done.” said Hunter. “Just turn them on and walk away;
no external control panels or additional
equipment required. It saves hours.”
Because of Oklahoma’s super harsh
groundwater – with more than 10 grains
of hardness per gallon – tank-type water
heaters at the original schools failed rapidly. In 2010, the district started replacing tanks with wall-hung, condensing
tankless units throughout all buildings.
“Over the years, we tried a variety of
different gas-fired tankless water heaters,” said Elliott. “Units with copper
heat exchangers would last no more
than nine months before corroding. We
settled on the Navien units because of
their dual stainless steel heat exchangers.”
Story continues on page 12.
Southern Plumbing•Heating•Cooling Magazine 11
PHC
Cover Story
Two Navien NPE-240A tankless water heaters serve a janitorial space, with a mop sink and washing
machine (above). Navien units that serve bathroom groups are located high in closet spaces with
storage below and set only to 110°F in order to avoid the possibility of scalding students.
“There are 40 or 50 of these units installed across the district,” he continued.
“We have a commercial Scale Blaster electronic water descaler on the cold water
line at each bank of water heaters, and we
manually de-lime the units once a year.
We simply don’t have issues anymore.”
Solid School Solution
“Elliott and his six maintenance guys
are in charge of all the plumbing systems in the district, and they really know
their business,” said Hunter. “They service all of their own units and are still
installing tankless units any time a tank
fails at one of the older buildings.”
For an elementary school application,
Elliott finds that the tankless technology can’t be matched. The units that
serve the bathrooms and common areas
are all set back to 110°F, while the units
in the kitchen heat water to 140°F before
sending it to the wash room and food
prep areas.
“This is an elementary school,” said
Elliott. “On top of that, we have special needs students. There’s no better
way to ensure safe water delivery than
when the unit doesn’t even produce
water at a dangerous temperature. And
because there’s no body of warm water,
the presence of legionella bacteria isn’t
even a consideration.”
In the kitchen, sealed combustion of
the Navien units is a huge help. Large
fume hoods exhausting air from cooking
areas could potentially create a negative
pressure environment. With atmospheric
combustion, this could lead to problems
ranging from incomplete fuel burn to flue
The key to overcoming
countless obstacles
was working harder,
working smarter and
using the best products
for the application.
gas passing back into the occupied space.
“Combustion air is one less consideration with these units when it comes
time to design a system,” said Hunter.
“Especially when you have a high water demand, it’s nice not having to think
about where your CFMs are coming
from.”
Another added benefit to tankless
12 Southern Plumbing•Heating•Cooling Magazine
technology is the floor space saved. The
school was spending — in rough numbers — $200 per square foot on the new
buildings. Considering a single commercial sized water heater needs up to
25 square feet, eliminating a single tank
means a savings of nearly $5,000 during
construction.
In his own home, Hunter’s domestic
hot water is supplied by the first Navien unit sold in the state of Oklahoma.
He says, “while the durability and efficiency of the units is a major advantage, it’s the field support and product
warranty that allow him to confidently
install dozens each year.”
Elliott appreciates the customer support as well, and mentioned that after
the tornado, he’d actually had Navien
service agents asking him about the disaster. While he and other tradesmen
worked late into many evenings, they
never had trouble getting a live person
on the other end of the line.
Built to Last
“The new schools were completed in
plenty of time for the 2014/2015 school
year,” said Elliott. “Since then, we’ve
not had a single issue with any of the
water heaters, or any real challenges
with the HVAC systems, either. All the
trades involved really poured themselves into the work.”
The district continued class in an old
school and a large church until the new
buildings could be occupied. As the
third largest district in the state, Moore
has more than 20,000 students, and it’s
growing rapidly.
The schools, similar to the new homes
in the immediate area, have been built
with tornado shelters large enough for
the whole student body.
“The new schools are built to protect
our most valuable asset; the kids,” said
Elliott. “And barring another direct hit
from tornado, so are the systems inside.
We’re so grateful for the dedication and
hard work from everyone involved,
whether that be the local tradesmen or the
volunteers from around the country.” n