ASHRAE Journal - December 2014 - 90

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University of North Texas Experiences Big Savings Using AERCO
Like most things in Texas, the plans to upgrade the heating
and hot water systems at the University of North Texas in
Denton are big. While the entire project entails nearly 70
boilers and water heaters, the largest part of the renovation
for the school nicknamed "mean green" may be the energy
savings associated with the new systems. That's because
by installing high-efﬁciency AERCO Benchmark gas-ﬁred

boilers and Innovation tankless water heaters the school
has realized tremendous operational beneﬁts, including a
new heating system that consumes 57% less gas and offers
enhanced uptime reliability.
University administrators planned to upgrade their existing
systems with new high-efﬁciency boilers and water heaters
for a few reasons. One was that the large central steam plant
that supplied most of the heating for the classroom and
administrative buildings was antiquated. The other was that
as the school grew to become the fourth largest college in
Texas and one of the 30 biggest in the United States, it had to
periodically add facilities. Separate steam boilers or hydronic
boilers that peaked at 80% efﬁciency were used for each
administrative or educational building as it was constructed,
creating operational inefﬁciencies.
Heating and hot water systems for the residence halls
were also in need of upgrades. Each dormitory used a steam
boiler for space heating and a mix of either indirect steam
storage tank heaters or direct-ﬁred storage heaters that
operated at 82% efﬁciency.
A Highly Efﬁcient Plan
The ﬁrst phase of the project consisted of the central
plant and outlying facility buildings, which are under the
supervision of the school's Facilities Department. AERCO
Benchmark 3000 (BMK3000) high-efﬁciency boilers,
which have full-ﬁre input capacity of 3 million BTU/
hr., were installed into each of the outlying buildings.
The retroﬁt went off without a hitch, and the units began
reaping beneﬁts almost immediately. Due to the successful
conversion of these buildings, it was agreed that ﬁve
BMK3000 units would be installed in the central plant.

The Facilities Department standardized on the Benchmark
family because it had low cost of ownership due to three
key reasons:
* High Efficiency - With 15:1 turndown, the BMK3000
boilers achieve 96% efﬁciency to maximize fuel savings
for the university.
* Uptime Reliability - A stainless steel heat exchanger
increases the reliability and life of the boilers.
* Maintenance - Compared to the previous system at the
school, the BMK3000 had minimal maintenance and
subsequently lower service costs.
Making Students Comfortable
Learning from the lessons of the Facilities Department, the
Housing Department also turned to AERCO when it began
to upgrade the student center and 14 dormitories. Given
that the housing facilities had equal or larger domestic
water heating requirements compared to space heating, a
water heater was necessary rather than a boiler.
After studying the alternatives and comparing them
to the needs of the residence halls, it was decided that
the AERCO Innovation 1060 tankless on-demand water
heater was a smart choice. Like the Benchmark family, the
Innovation units have the features to meet the university's
requirements, including a small footprint for easy
retroﬁtting, a reliable stainless steel heat exchanger design,
and high efﬁciency of 96%.
Six Innovation 1060
water heaters were installed
in three dormitories and
the Student Events Center.
At Kerr Hall, the ﬁrst dorm
to be converted, two units
were installed with zeroside clearance in the same
footprint as a single leaking 250-gallon storage heater. One
Innovation unit now handles the entire load of the 300room dorm without the need for storage. By installing two
water heaters, the facilities managers can alternate between
each unit monthly to extend the life of the units. Another
beneﬁt is the tankless design, which reduces the footprint of
the water heaters, as well as virtually eliminates the risk of
Legionella bacteria growth.
Five more dormitories are slated to be retroﬁtted with
AERCO Innovation units by the end of 2014, when the
project is scheduled to be completed. In all, the university
will have installed 16 Innovation 1060 water heaters and 50
BMK3000 boilers across the 900-acre campus.
Signiﬁcant Energy Savings
The University of North Texas has been experiencing
efﬁciency beneﬁts throughout the renovation. For example,
during the 2012-2013 heating season, the new central plant
consumed 6,465 mcf of gas, a 57% decrease from the 11,389
mcf the old system used during the prior heating season. With
results such as these, it's easy to see why the AERCO units
have received high marks with the university administrators.

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ASHRAE Journal - December 2014

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