1

SourceThe International Ground Source Heat Pump Association Newsletter

November/December 2001 Volume 14, Number 6

Stay in the Loop

The

IGSHPA • Headquarters: Oklahoma State University

Inside. . .

InternetResources ............... 2

ExperimentalObservations ......... 3

Calendar ofEvents ..................... 5

WEEC was a greatopportunity for

IGSHPA to promotethe ground source

heat pump industry

The geothermal industry was afeatured track at the World Energy EngineeringCongress (WEEC), held October 24-26 in theGeorgia World Congress Center in Atlanta,Georgia. WEEC is an opportunity to getcutting edge information about innovations inthe energy industry. At the 24th annualconference, 3,019 attendees listened tospeakers, attended workshops, and browsedexhibits, speaking with 960 exhibitors. Theconference featured a geothermal track, withspeakers promoting and discussing thegeothermal industry. The exhibit hall alsofeatured an area for exhibitors in thegeothermal industry.

IGSHPA staff exhibited at the conferenceto promote geothermal technology and theCertified GeoExchange Designer (CGD)

course. This intense course is targeted atexperienced architects or engineers who wantspecific information about ground source heatpump design.

Prior to the WEEC Conference, IGSHPAconducted a Certified GeoExchange Designercourse at the Georgia World Congress Center.Sixteen students enrolled in the CGD course,with three of the students being engineersfrom Korea. Students spent time in theclassroom with industry experts and took anexamination at the end of the course.

WEEC was a great opportunity for IGSHPAto promote the ground source heat pumpindustry and to educate attendees about thebenefits of this efficient technology. To findout more information or to enroll in an IGSHPAcourse or workshop, call 800-626-4747.

WEEC Conference FeaturesCGD Classby Kerri Tate

What’s up with The Source this month? HasSt. Patrick’s Day come early?

No! The Source has temporarily turned greenin eager anticipation of next year’s Green Book!

So what is The Green Book? The Green Bookwill replace the IGSHPA Membership Directoryas the industry resource for professional contacts.Like the Membership Directory, it will featureIGSHPA members by type of business,geographic area and alphabetically.

The Green Book will be printed in acompact size (6 x 9 inches) making it aconvenient, portable reference. All members willreceive one free copy, with additional copiesavailable for a nominal fee.

The Green Book will also be sold to non-members through the IGSHPA website and atindustry trade shows.

For more information on The Green Bookand advertising opportunities call 1-800-626-4747.

A New Look for The Source?

2

499 Cordell South

Oklahoma State University

Stillwater, OK 74078-8018

Phone: 800-626-4747

Fax: 405-744-5283

www.igshpa.okstate.edu

The Source is published bimonthly by OSU and the InternationalGround Source Heat Pump Association, 499 Cordell South,Stillwater, OK, 74078-8018, as a service to the membership.Send questions, story ideas, photos, and comments to Editor,The Source, c/o IGSHPA, or call 800-626-4747. Visit our website at www.igshpa.okstate.edu.

Copyright 2001 by the Board of Regents for the OklahomaState University Agricultural and Mechanical College, all rightsreserved.

Use of copyrighted material is permitted, provided the reprintcredits IGSHPA and The Source, and a copy of the reprint issent to the IGSHPA office.

IGSHPA Advisory CouncilDan Ellis, ChairClimateMaster

Howard Newton, Vice ChairTrane/Command-Aire

Vacant, Secretary

Billy Abner, East Kentucky Power Coop.

Phil Albertson, Ditch Witch

Larry Eitelman, Florida Heat Pump

Morris Lovett, OG&E

Frank Migneco, GPU Energy

David Sabatino, Carrier Corporation

Ron Robertson, Energy Assets

Phil Schoen, Geo-Enterprises, Inc.

Chris Smith, Florida Heat Pump

Mark Sullivan, WaterFurnace International

Greg Wells, Middleton Group

Ex-Officio Members

Lew Pratsch, DOE

Carl Hiller, EPRI

Conn Abnee, GHPC

IGSHPA StaffExecutive Director, Jim Bose

Assistant Director, Lisa McArthur

Director of Research, Marvin Smith

Development Engineer, Randy Perry

Publications Coordinator/Web Master, Jeanne Knobbe

Special Projects & Training, Jim Netherton

Conference Coordinator, Shelly Fitzpatrick

Financial Assistant, Kelli Hill

Receptionist, Amanda Collins

Training Graduate Assistant, Jay Davidson

Interns, Mohammed Khan, Chee Jeng Lau, Kerri Tate

Down to Earth Energy

Internet Resources forGeothermalTechnologyBy Trina Walker

The Internet is a powerfultool in today’s fast-paced, hightech society. The world is at yourfingertips. One can check oneverything from stock prices toinformation regarding geothermaltechnology. The questionis,where to start?

• A quick search located the U.S.Department of Energy’s, EnergyEfficiency and RenewableEnergy Network (EREN) page atwww.eren.doe.gov. This sitelinks to many renewable energyresource pages. The geothermallink allows one to findinformation regarding heatpumps as well as advancedtechnologies andenvironmental advantages. Thegreatest value to this site maybe the contacts. Theopportunity to discusstechnology and research withprofessionals around the worldis just a click away.

• An interesting web site is TheGeothermal Resources Councilat www.geothermal.org.The pages’ main intent is topromote membership

opportunity with the council,however this is also a goodlocation to find more contactsand to keep up on currentindustry events. A listing ofbooks and other researchmaterial available for purchaseis also found here.

• Another site of interest isDemarco Energy Systems atwww.demarcoenergy.com/home.cfm. This is a site for acompany specializing ingeothermal heat pumps. Here,one can read case studies, newsand press releases. Demarcoalso offers online subscriptionto news and press releases. Thispage is interesting because itshows how geothermaltechnology is being used andmarketed in the real world.

This brief overview ofInternet sites is just that–brief. Itis a starting point for finding moreinformation and contacting withothers interested in this work.Many other sites are available. TheInternet may not replace hands onresearch but it is a valuable tool.A quick search can lead to vastamount of information.

Bulletin Board

3November/December 2001

The Source

GeoClip U-Bend Installation vs.Standard U-Bend Installation

The GeoClip was specifically designed to maximize borehole thermalconductivity, yet facilitate superior borehole grouting to protect theenvironment in Vertical closed loop heating and cooling wells. Researchindicates that positioning up-bend pipes at the borehole wall directlyacross from one another significantly increases the heat transfer rate ofthe vertical heat exchanger over a standard installation, regardless ofthe backfill or grouting material used.

Standard• Random pipe

positioning• Random pipe

separation• Inferior heat

transfer

GeoClip• Optimum pipe

positioning• Optimum pipe

separation• Superior heat

transfer

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www.geoclip.com

IntroductionRecent experiences with an architect showed a need for more

information regarding pond water temperatures. The plan was to use aducted air system through pipes in a pond. A fan would return the air toan air space under the floor, around the walls and the ceiling to cool thebuilding at night during the summer. A ground source heat pump (GSHP)would be used during day. Unfortunately, the water in a pond fed byrainwater run-off in the southern half of the United States is often toowarm to approach cooling with this method. Water sources from pondsand municipal water sources are being explored in an attempt to reducethe high-energy costs in cooling buildings. Before designs can beimplemented it is necessary to know the temperature ranges expectedfrom these water sources.Background: Test System

A 3.5-acre pond constructed at Oklahoma State University (OSU) isused to investigate cooling and heating applications associated with bodiesof water. The pond is 17-feet-deep in areas. A test bridge constructed

over a portion of this pond is equipped with a ground source heat system.The bridge deck is 20-feet-wide and 60-feet-long. E-PexB pipe loopsimbedded in the bridge connect to a ten-ton water-to-water heat pump.This system heats the bridge, preventing the buildup of ice and snow, thusincreasing bridge safety while decreasing maintenance. The energysources feeding the heat pump are a vertical borehole field of sixboreholes, and a set of three, four-ton flat plate “Slim Jim” heat exchangersmounted in a submerged vault. Both, pond and hydrant water are usedto supply vault water. Hydrant water is carried through a six-foot-deepsupply line to ensure temperature stability. Pond water comes from atwo-foot vertical intake submerged in nine-feet of water. Each methodmay be used simultaneously.

Preliminary tests of the flat plate heat exchangers provided the dataconcerning hydrant source and pond source temperatures. Flow ratesfrom the hydrant and pond water sources were each around 20 gpm.The two-inch diameter distribution pipe used for each source enters aburied concrete control room.Flat Plate Heat Exchanger System

In the foreground of Figure 1 (page 4) you will see the heatexchanger vault. Baffles near the wall of the heat exchanger vault guidethe exiting water. Three flat plate heat exchangers are spaced between the

Experimental Observations of Pond and Hydrant Flowing WaterTemperaturesby Marvin Smith, Ph.D.,P.E.Oklahoma State University

(continued on page 4)

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4 Down to Earth Energy

baffles. The vault is eight-feet high and five-feetwide. The heat exchangers are six-feet by four-feet by 3/8 inch. Each is rated at a four-toncapacity with 12-gpm flow rate.

The control vault for the heat exchanger isalso pictured in the middle of Figure 1. Waterfrom the pond enters the control room on theleft. Hydrant water enters on the right. A portionof the bridge deck, pond and the bridge controlbuilding are seen in the background of this view.

Figure 2 (page 6) shows the front of thecontrol vault after the lid on the heat exchangerhas been installed and backfilling has taken place.The manhole containing the control valves for theheat pump connection to the vertical boreholefield is in front of the control vault. The boreholefield is left of the manhole, and the flat plate heatexchangers. Lines run from the manhole to theheat exchanger field. Two conduits containinstrumentation, control wires, and electricservice wires. Heat pump supply and return linesalso run from the manhole to the control vault.

A 50-foot-long trench running from thefront corner of the control vault to the pond

contains a two-inch HDPE suction. This suctionline extends 75-feet into the pond and issubmerged in nine-feet of water. A piece of pipeconnected by a 90º ell to the main line pumpswater from a depth of seven-feet. A deviceattached to the end keeps it facing up whensubmerged into the pond. A coarse screenplaced over the end keeps debris and fish out ofthe line. Another trench extends from theopposite corner of the control vault to the pond.Water is discharged from the vault using ascreened three-inch PVC line laid in this trench.Inside the control vault are the control valve, apump, thermistors, a flow meter, back flowpreventor and strainer. Motorized control valvesallow for computer control.

There are also thermistors in the heatexchanger vault and two outside the vault buriedin soil. The sensors are connected to thecomputer in the bridge control building.Temperature Profiles

Tests ran in July and August 2001 partiallyfulfilled the requirements for the OSU SmartBridge research project funded by the US

Department of Transportation. Pond hydrantwater temperatures were obtained as a part ofthe overall project. This information ispertinent to the design of systems using waterfrom either of these sources for buildingcooling systems.

Figure 1.A heat exchanger vault and a control vaultpictured to the left are part of a ground sourceheat system being tested on a Smart Bridgeresearch project funded by the US Departmentof Transportation. This energy savingtechnology is becoming increasingly importantin the reduction of energy usage and cost.

(continued on page 6)

5November/December 2001

The Source

December 7-9, 20012001 Ground Water ExpoNational Ground Water AssociationNashville, TNwww.ngwa.org/convention/national.html800-551-7379

February 8-11, 2002International Home Builders ShowNational Association of Home BuildersAtlanta, GAwww.buildersshow.com/2002/02welcome.shtml800-368-5242

February 27-March 2, 2002ACCA 34th Annual ConferenceAir Conditioning Contractors of AmericaKissimmee, FLwww.accaconference.com703-575-4477

March 11-15,2002Train-the-Trainer WorkshopInternational Ground Source Heat Pump AssociationStillwater, OKwww.igshpa.okstate.edu800-626-4747

March 13-15,2002IGSHPA Installation WorkshopInternational Ground Source Heat Pump AssociationStillwater, OKwww.igshpa.okstate.edu800-626-4747

Calendar of Events

Mark YourCalendar!

6 Down to Earth Energy

GHPSYSTEMS

The first test in the series began on July 12, 2001. The data obtainedduring this testing is shown in figure 3. For the initial test the hydrantwater line provided all the water to the vault heat exchanger. The airtemperature was about 104ºF, the six-foot soil temperature was around79ºF, and the hydrant water flowing temperature was 79ºF. Fluctuationsin air temperature occurred. The hydrant water temperature fluctuated ata delayed and dampened rate. The response of the soil temperature wasmore pronounced than the hydrant water flow. A high-density layer ofrock running toward the pond above the thermistor caused the soiltemperature to change at a faster rate. The heat transferred through therock alone at a faster rate than it would through both soil and rock. Thecombination of heat from the sun, and ambient conditions allowed for amuch a faster temperature response.

The second test series was conducted with both the pond pump andthe hydrant valve open simultaneously. Water supplied to the heatexchangers was discharged into the pond at a higher total rate. Airtemperatures remained high between the first and second test periods.Soil and water temperatures continued to increase due to the heat. Whenthe test began on July 23, 2001 the air temperature was above 102ºF andthe six-foot soil temperature was above 78ºF.

The hydrant water temperature was 80ºF and increasing. The pondwater flowing temperature was 85ºF and increasing at approximately thesame rate.

On July 28, 2001 Oklahoma Mesonet data showed that it rained 1.97inches in Stillwater. The high temperature was 100ºF and the lowtemperature was 71ºF. See figure 3. for details of these variables. Rainand cooler air temperatures had more influence on the pond flowtemperature than on the hydrant temperature. There was an abruptdecrease in pond water flowing temperature following the rain and coolerweather. The hydrant water temperature did not change as drastically.

The hydrant valve was closed on July 30, 2001. This testing periodwould determine how well pond water alone would handle the temperaturechanges. During this test the pond water flow temperatures increaseddue to increased air temperatures. On August 2, 2001 it rained 0.38inches, resulting in a lower pond temperature. Air temperature did notdecrease significantly so the primary cooling was caused by the rain andrun-off from the surrounding area.

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Figure 2.The manhole pictured to the left allows access to control valves for thevertical borehole field’s heat pump connection. Trenches are dug to holdlines running between the manhole and the control vault. Inside thecontrol vault are the control valve, pump, thermistors, flow meter, backflow preventor and strainer.

7November/December 2001

The Source

A debugging test took place on August 16,2001 showing a decrease in the generaltemperature trend. Another test was conductedon August 22, 2001 using the hydrant water flow.The trend followed the air temperature, as it wascooler than in previous tests.

In general the water temperature followedthe air temperature at a delayed rate. It wasanticipated that the flowing hydrant watertemperature would be less than the six-foot soiltemperature. Tests were run on several hydrantsin the region. They were all similartemperatures. Water from a hydrant 650 feetfrom the control vault measured within 0.2ºF ofthe hydrant flow temperature in the control vault.This line feeds directly into the system. Thus,the source of higher temperature is upstreamfrom local hydrants. Lakes supply the water forStillwater and OSU.Applications and Commentson Water Sources

If the application were to duct air throughthe pond so that the heat would be rejected tothe pond from the building, the buildingtemperature would only be cooled totemperatures in the range of 2ºF to 6ºF higher

than the pond temperatures. Figure 3. showsthat 87ºF source temperature would be themaximum expected for this particular year. It isclear to see that this method was not effective.

A maximum entering water temperature fora GSHP is typically set at 90ºF. The entering watertemperature is determined by loop length. Withthe given pond temperatures one is able tooperate with an open or a closed loop system.Using an open loop system the temperaturewould provide an entering water temperatureno higher than 87ºF. This temperature can bemaintained even during extreme summer heat.When using a closed loop system the enteringwater temperature would be dependent uponthe loop lengths and the loop material. Thissystem comes closer to obtaining the 90ºF designvalue. An example is the Bridge Control House.It is heated and cooled with a one-ton heat pumpand 60-feet of copper coil in the pond. The coilis in a 12 to 14 foot portion of the pond with anentering water temperature of 84.4ºF. At thesame time the pond water flowing temperatureis about 85ºF.

A news release reports that WaterFurnaceInternational, Inc. in Fort Wayne, Indiana, is

forming a joint venture with HardinGeotechnologies in Indianapolis, Indiana. WaterFurnace will market a technology that deliverswater from the local water company to any homeor commercial building as a free source ofheating and cooling. The joint venture is knownas water+Æ. It is an independent operationavailable to all heating, air conditioning andrefrigeration manufacturers making geothermaland water source units. Water supply systemswill be used more and more frequently asresearch improves. It is important that theapplication design is dependent upon the watersource temperature. As demonstrated by thetest data, temperatures in the low 80’s could beexpected. In comparison with some otheralternatives this provides favorable enteringwater temperatures.Conclusions

This article provides only examples oftemperature profiles of some water sourcesviable for geothermal heat pump applications.It dispels perceptions that the temperature ofpond and municipal water supplies are often inthe 60’s. In some areas of the United States thesetemperatures are cooler and data needs to beassembled to determine the local temperatureprofiles for design purposes.

The trend in hydrant and pond temperatureprofiles is highly dependent upon the ambienttemperature history. At the same time hydrantand pond temperature profiles depend on thewater source.

Even in the hot weather of Oklahoma, pondand hydrant water sources are good potentialenergy and cost saving sources when coupledwith ground/water source heat pumps. Reliabledesigns are based upon reliable data. Furtherstudies are needed to produce models forpredicting good design temperature values.Acknowledgements

This material is based upon work supported by theFederal Highway Administration under Grant No. DTFH61-99-X-00067. Any opinions, findings, and conclusions orrecommendations expressed in this publication are thoseof the author and do not necessarily reflect the view ofthe Federal Highway Administration.

This paper could not have been written without theable assistance of Fred Schroeder, Bill Holloway andDustin Earnhart.

Figure 3.The above graph details the correlation between air temperature, pond water temperature,hydrant water temperature and ground temperature during each testing phase.