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					                                                                                                   Solar Thermal for
                                                                                                   Domestic Hot Water
                                                                                                   Commercial Case Study

Rising utility costs and growing sentiment    before students returned from summer           Project: Landmark College
for reducing the carbon footprint of          break – leaving crews with a short             Location: Putney, VT
its facilities has prompted college           timeframe to finish the job. Within the        Application: Solar Thermal for DHW
campuses nationwide to explore alternative    strict installation time frame, Vermont        Equipment: 24 Buderus SKS 4.0 collectors
ways to curb energy consumption.              Heating and Ventilation was tasked with        2 Buderus KS0120 solar pump stations,
                                                                                             2 indirect 119 gallon storage tanks,
Already facing budget shortfalls in most      installing a solar thermal system for          2 Buderus G315 boilers for back-up
cases, schools, particularly smaller          efficient and sustainable domestic hot
universities and colleges, are turning        water production.
                                                                                             Buderus SKS 4.0 Collectors
to the latest technologies in energy                                                         Product Details:
solutions to meet demand, reduce costs                                                        Coating: Highly selective PVD
                                              Vermont Heating and Ventilation installed
and be a better steward for the planet.
                                              twenty-four Buderus SKS 4.0 collectors          Absorptivity: 95% ± 2%
With a full portfolio of sustainable
                                              in Aiken Hall to pre-heat the domestic
comfort solutions, Bosch Thermotechnology                                                     Emissivity: 12% ± 2%
                                              hot water. The 24 collector system is
has been an integral partner for                                                              Max. Operating Pressure (bar):
                                              divided into four rows of six collectors,
campuses nationwide faced with these                                                          145 psi (10)
                                              each mounted to the dormitory’s
circumstances.                                                                                Nominal Flow Rate (L/Hr): 0.22 GPM (50)
                                              southeast facing roof at a tilt angle of       u	
Landmark College                              23 degrees. Achieving the best balance          Absorber Material: Copper with
Landmark College, a private college with      between optimized system performance            ultrasonic welding
an enrollment of 500 students is located      and an architecturally acceptable               Absorber Type: Double meander
in south-eastern Vermont, and is one          appearance is often times a challenge
                                                                                              Collector Construction: Hermetically
of the only accredited colleges in the        with solar collector installations. Ideal
                                                                                              sealed argon gas
United States designed exclusively for        positioning for year round domestic hot
students with specific learning disorders.    water production in this location would
Aiken Hall, a student dormitory situated in   typically require a collector tilt angle
the heart of the campus houses 70 students    closer to 42 degrees with a direction of
and has 23 bathrooms. The 1960’s era          due south. By using the highly efficient
dorm rooms and facilities needed a            Buderus SKS 4.0 collectors the tilt
renovation since its original opening         angle and direction of the roof could
in 1962. Landmark College officials not       be used with only a 4% drop in overall
only wanted a more modern look for the        system performance.
dorms, but also wanted a more eco-friendly
                                              The 24 collectors where split into
and energy efficient building.
                                              two parallel groups of 12 collectors,
The major challenge of this project was       with each group of 12 supplied with
the renovation timeline. School officials     its own KS0120 solar pump station.
wanted the installation completed             The two parallel circuits feed into a single
primary loop supplying a 199 gallon
preheat storage tank. The preheat tank
is piped in series-parallel with two 119
gallon storage tanks with a recirculation
line connecting all three tanks together
to allow for the combined 437 gallons
to be used as preheat storage. Finally,
this preheated water feeds into two
119 gallon indirect tanks. The indirect
tanks are once again connected back
to the preheat system using a second
recirculation line in the event that the
preheat system exceeds a predefined
temperature in relation to the indirect
tank temperature.

This allows for the combined five-tank
system to contribute the full 675 gallons
to the solar system during high insolation
periods. If needed, during periods of
no solar gain, the two 119 gallon indirect
tanks are heated using two Buderus
G315 boilers. This multi tank system,
using three stages of storage, allows the
ratio of storage/collector to vary from
8.3 – 28 gal/collector depending on
the current system conditions.

Benefits and Conclusion
The Bosch solar thermal system has
been running for just over two years and
so far has saved 4500 gallons of fuel oil,
adding up to a total savings of $13,500.

 Aiken hall also received the addition of
a third floor, expanded accommodations              of the Leadership in Energy and
and an expansion on recreational spaces.            Environmental Design (LEED) Green
The dormitory meets the five categories             Building Rating System established by
                                                    the Green Building Council.

Bosch Thermotechnology Corp.
Londonderry, NH • Ft. Lauderdale, FL • Irvine, CA
General Inquiries: 1-800-283-3787
Technical Support: 1-866-330-2725

77700224A                                                                                   Copyright © 2012 Bosch Thermotechnology Corp. All rights reserved.

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