26•
•THE WHOLESALER® —MAY 2011
Earth Energy Geothermal not retiring
(Continued from page 24.)
free water we’ve ever seen, and the rock was also very stable.” The aver- age water temperature across all the wells was 52°.
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 to 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 bal- ancing. The well heads should be kept at the same elevation across the field. Since MCNH rests on a hill, the two fields are roughly 5 feet apart in elevation from each other. As customary for all standing col-
umn well systems, no circulators are used; there aren’t even any flow cen- ters on the ClimateMaster units. Pressure at the mechanical room
The FBC System
eliminates the guesswork by identifying products that do
m Compatible Progra do go together.* r.*
Combining products that ar en’t meant to be used together can jeopar dize the reliability of any piping system due to chemical incompatibility. Only FBC™ Building Solutions pr ovides added peace of mind with a unique program that thoroughly tests ancillary products, such as caulks and thread sealants, to confirm compatibility with FBC piping systems— FlowGuard Gold,® BlazeMaster® and Corzan.®
*
Why take chances? Specify FBC piping systems and FBC System Compatible pr oducts with confidence.
™ am
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, in- suring 25 psi at the furthest, fourth
the building at peak flow. Suspended above drop-ceiling tiles
are either 3- or 4-ton ClimateMaster TS units with copper-nickel heat ex- changers. The majority of the units serve two bedroom areas. A big ad- vantage in having many small units — as opposed to a large, central unit for
and the technical solutions that were offered.”
“I was really impressed with everyone involved
each floor — is sanitation. With the smaller systems, air movement is lim- ited to two rooms, greatly reducing the threat posed by airborne pathogens. “I was skeptical at first,” said Sid
McDonald, director of facilities at MCNH. “The bugs got worked out the first year the system was in, and ever since then, it’s has been phe- nomenal. I was really impressed with everyone involved and the technical solutions that were offered.”
Btu gusher; a “geo dream” According to Carl Orio, most stand-
ing column wells are designed to bleed off 10% of the water used. In the case of MCNH, the wells were designed to bleed off only 5% of the geo-exchange water. This was done to prevent water from overfilling the property’s deten- tion pond which would then put it on a downhill course and into Merri- mack River, requiring another, higher level of environmental permitting. Yet aquifer flow under MCNH
The courtyard outside the nursing home is bright and inviting.
floor heat pump. “You take the furthest well and the
most distant heat pump, and that gives you the requirement for sizing the submersible pumps,” said Orio.
Pathogenic purity
For more information about the pr view a list of proven compatible pr
www
e information about the program or to oven compatible products, visit
www.fbcsystemcompatible.com or call 888.234.2436, ext. 4477393.
* Since CPVC compounds differ r Use FBC compatible products with other brands of CPVC piping at your own risk. See contact information on page 102 “Two key things come together
when determining system head pres- sure,” said Orio. “The design engineer determines the TDH (total dynamic head) in the building, and the geother- mal engineer determines the TDH from the well to the manifold.” Together, these provide the pres- sure drop to the highest heat pump in
was much better than expected. The flow of water in the wells is so steady, easily maintaining de- sign temp despite the influence of system geo-exchange, that there’s no need even for a 5% bleed-off of water. But it gets better. So rich and steady is the supply of water-
borne Btus that, for eight or nine months of the year, only 10 of the 16 wells are used. So, just to keep things equal in the wells, Btus are tapped from different wells on a rotating basis year-round. “It’s really amazing how well the
system has worked out, almost like a dream,” said Skillings. “By rotating wells, MCNH not only saves even more electric, but conserves pump life and the aquifers as well.” The system is a great example of
what can be achieved when several outstanding companies come to- gether for one project.
n • Be sure to visit
www.thewholesaler.com for web exclusive articles and videos! •
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