HYDRONICS Retirement facility goes geo
against the certainty of increasing energy rates, managers of Merrimack County Nursing Home (MCNH), in Boscawen, N.H. invested deeply in geothermal technology. Today, they and hundreds of residents there celebrate substantial savings and new levels of comfort and air quality. It was back in 2005 when
G
Hampstead, N.H.-based Water Energy Distributors, Inc. was hired as a subcontractor by the engineering firm, McFarland-Johnson, to design an all-geothermal mechanical system
eothermal energy gives new life to this retirement community. As a hedge
he brought his daughter Christina into the business as general manager. In 2000, she became president of the firm. All along, the focus has been the sale and design of sustainable, renewable energy systems. So, as one generation encourages
involvement of the next, mechanical challenges like this one benefit from decades-old vision and expertise, and the latest technology.
No job too big “At MCNH, the first order of
business was to closely study the area’s hydrogeology to determine the best location for the well field. Water
The courtyard outside the nursing home is bright and inviting.
the driller contracted for the MCNH job. The company had two of their four drilling rigs on the job, operated by five employees. “Each well took us about six days to
drill,” said President Roger Skillings. Drilling an eight-inch hole through 1500 feet of solid granite is no small task; it was a blessing in disguise, though. According to Skillings, the number-one enemy of a healthy standing column well is soft rock that cracks, collapses and caves in. “The first thing we do at any job
44
that is to include a standing column well, is to drill a test well,” explained Skillings. “If the rock hardness, density, and the quality of the water are all desirable, that test well becomes the first well on the field.” At this site, we found some of the best, mineral-free water we’ve ever seen, and the rock was also very stable.” The average water temperature across all the wells was 52 degrees.
A technician from Merrimack County Facility Maintenance conducts a diagnostics check on the geo-exchange system at the Merrimack County Nursing Home.
for MCNH. Work on the system — installed in several stages as the facility went through various construction phases — was just completed. The 235,000-sq.-ft. facility has a
staff of 425, and 290 beds with luxury accommodations for elderly residents. Merrimack’s über-green mechanical system incorporates 16 standing column wells and 326 ClimateMaster water-to-air heat pumps for a total of 615 tons of capacity.
Looking back Success of the facility’s job ties to
early development of an energy- tapping technique developed by the founder of Water Energy Distributors. Carl Orio spearheaded development of the standing-column geo- exchange well almost 35 years ago. Today the company he founded in 1981 is recognized as a global leader in geothermal design and distribution. The standing column well is now
regarded as offering one the highest efficiencies of any geo-exchange system. Three years after Carl Orio
incorporated Water Energy Systems,
Energy was instrumental in determining optimal well spacing and number of wells within the identified area as being most suitable for geo-exchange,” said Fred Mock, vice president of Binghamton, N.Y.- based McFarland-Johnson. “Based on the heat load, we
recommended 16, 10-8-6 wells, each 1,500 feet deep,” said Orio. The term
“10-8-6” stands for a 10-inch casing sealed into the bedrock, an 8-inch rock bore, and a 6-inch sleeve and pump. Each submersible pump has a 10-hp motor to push water to the building’s mechanical room, and from there to all the heat pumps within the system. All 16 wells are located beneath
the nursing home’s parking lot. Split up into two well fields, eight wells are located under the upper parking lot, and eight below the lower, with the farthest well being 850 feet from point of entry into the building. Each eight-well field is piped to its own supply and return manifold. The caps are protected by manhole covers, and can be found in the green spaces between parking areas. Amherst, N.H.-based Skillings and Sons was
System details “Each of the eight-well supply and
return manifolds feed well water to a series of risers to the upper floors,” explained Orio. “There are two of the big manifolds; each field feeds half of the building. We generally prefer to have no more than 10 wells, or 300-400 tons, on a given field. At MCNH, there’s a nominal 310 tons on each field.” According to Orio, limiting the
fields to 10 wells is for ease of balancing. The well heads should be kept at the same elevation across the field. Since MCNH rests on a hill, the two fields are roughly five feet apart in elevation from each other. As customary for all standing
column well systems, no circulators are used; there aren’t even any flow centers on the ClimateMaster units. Pressure at the mechanical room
supply manifolds are maintained by the VFD-controlled submersible pumps, which operate in parallel. Pressure in the manifold that serves the upper field is kept at 52 psi, and at 55 psi for the lower manifold, insuring 25 psi at the furthest, fourth floor heat pump. “You take the furthest well and the most distant
e Continued on p 46
phc march 2011
www.phcnews.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72