A Buyer’s Guide for Residential Ground Source …

1 A Buyer s Guidefor ResidentialGround Source heat Pump SystemsA Buyer s Guide for Residential Ground Source heat Pump SystemsThe aim of this publication is to help readers with the decision to purchase and install a Ground Source heat pump (or geoexchange) system. This document is not meant to be a do-it-yourself buyers should seek out qualified advice and assistance tosupplement the information provided here. The Canadian GeoExchangeCoalition, as part of its market transformation initiative, has trained and accredited thousands of industry professionals since early 2007 and a list of qualified companies is available on its website considering the installation of a geoexchange system, customersshould contact utility and government agencies to ensure that their newsystem will respect relevant codes and standards, as well as building,site and other Canadian GeoExchange Coalition assumes no liability for injury,property damage or loss suffered by anyone using the information contained in this Guide .

2 It is distributed for information purposes of this publication are reproduced from other documents with thepermission of the Government of Canada and under fair use editorial work has been performed to provide prospectivecustomers with a critical decision-making tool that reflects the currentstate of the industry s market transformation and self-regulatory approach initiated and deployed by the Canadian GeoExchange Coalition. Canadian GeoExchange Coalition, 2009 ISBN 978-0-9811612-4-2 Aussi disponible en fran ais sous le titre : Guide d achat d un syst me g othermique r sidentielRecycled paperHOW TO USE THIS GUIDE21 INTRODUCTION TO GEOEXCHANGE SYSTEMS3 What is Earth Energy?3 How GeoExchange Systems Work3 GeoExchange System Variations7 Benefits of GeoExchange Systems10 Worksheet Example122 GEOEXCHANGE SYSTEMS FOR A NEW HOME15 Home Design Considerations 15 System Design for a New Home 15 Distribution Systems 17 Controls 17 The Cost of Owning a GXS 183 GEOEXCHANGE SYSTEMS FOR AN EXISTING HOME 21 Existing Site and Services 21 System Design for an Existing Home 22 Possible Upgrades24 Removal of Existing Equipment 244 CONTRACTOR SELECTION25 Chosing the Right Specialists25A Basic Contract265 MAINTENANCE AND TROUBLESHOOTING 28 Servicing Requiring a Contractor 266DO YOU NEED MORE INFORMATION?

3 29 GLOSSARY30 CONVERSION FACTORS 33 Table of ContentsA Buyer s Guidefor ResidentialGround Source heat Pump Systemsprovides homeowners with the information they need to plan forthe purchaseof a Ground Source heat pumpsystem in a new or existing home. Section 1is an introduction to GeoExchange Systems what theyare, how they work, the differenttypes, the benefits they provide andhow much earth energy they need to work. Whether you are buying orbuilding a new home, or planning to retrofit your existing home, you should read Section home buyers should then read Section 2. Here you willread about how your house design affects a GeoExchange System. It also recommends system designsthat work best for your house typeand compares their typical operatingcosts to alternative heating and cooling 3is for homeowners who want to install a GeoExchangeSystemin their existing home. Thedesign and system that are right forthe home you are living in now can bevery different from standard of this, and to make the installation of your new system aseasy as possible for you and your family, you need to plan.

4 This sectioncovers various ways you can upgradeyour heating and cooling system,compares their operating costs andlists important steps you should takewhen servicing your system. You willalso need to read certain parts of Section 2 that apply to your 4is important for all readers those buying or building a new home, as well as those retrofitting or renovating an existinghome. It provides guidance on selecting a contractor and what needsto be covered in a basic contract. Italso covers service and maintenanceas well as basic 5lists things to check beforecontacting your service 6provides sources of additional Guideends with a glossary ofterms used in the GeoExchangeindustry (given in italics throughoutthe Guide , like this: Ground water).The industry also uses other terms todescribe GeoExchange Systems: theyinclude Ground - and water-sourceheat pumps, earth energy system,and geothermal heat Buyer s Guide forResidential Ground SourceHeat Pump SystemsHow to Use this Guide1 What isEarth Energy?

5 The sun has always provided heat forthe earth. Its energy warms the earthdirectly, but also indirectly. Its heatevaporates water from the lakes andstreams, which eventually falls back to earth and filters into the Ground . Afew metres of surface soil insulate theearth and Ground waterbelow. Thewarm earth and Ground waterbelowthe surface provide a free, renewablesource of energy for as long as thesun continues to shine. The earthunder an average Residential lot caneasily provide enough free energy toheat and cool the home built on free energy has only to be movedfrom the Ground into your home. Thisis done either by pumping water from awell (open loop) or by pumping a heattransfer fluid through a horizontal orvertical circuit of underground piping(closed loop). The fluid, called theheat transfer fluid, absorbs the heat inthe Ground wateror soil and transfersit to the heat pump. The heat absorbedby the fluid from the solar-heatedground is extracted from it by the heat pump, and the now-chilled fluidis circulated through a heat exchangerover and over again to extract moreheat from the your home is located near a suitablepond or lake, you can use a Geo-Exchange System (GXS)to draw onthis excellent Source of free a loopin the Ground aroundyour home is like owning your own oilwell, but instead of pumping oil froman underground pool and burning it tocreate heat (and greenhouse gases),you tap into clean energy that will bethere for as long as there is a sun.

6 A well-designed Ground loopwill not hurt the earth or plants growingabove it. There is no visible part toshow that it is buried in your yard. If your system uses Ground water, ithas no effect on the water other thanchanging its temperature by a few degrees. Finally, a welldesignedground watersystem will not wastethe water, but put it back into theground by means of a return GeoExchangeSystems WorkThe heat energy taken from theground by your GXSis considered low-grade heat . In other words, it is not warm enough to heat yourhome without being concentrated orupgraded somehow. However, there isplenty of it the average temperatureof the Ground just a few metres belowthe surface is similar to (or even higherthan) the average annual outdoor airtemperature. For example, in Toronto,the average annual air temperature isabout C, but the average groundtemperature is C. It is importantto note that this Ground temperatureis C on the hottest day of summeras well as on the coldest day of is why some of the first humanslived in caves the caves would protect them from the temperatureextremes of winter and summer.

7 That is also why a GXS works so effi-ciently it uses a constant, relativelywarm Source ( Ground or water) fromwhich to draw Components of a GXSG enerally speaking, a GXS is made upof three main parts: a loop, the heatpumpand the distribution system. Thefollowing section describes some ofthe various loop designs, heat pumpsanddistribution systemscommonlyused in a Canadian loopis built from polyethylenepipe which is buried in the groundoutside your home either in a horizon-tal trench (horizontal loop) or throughholes drilled in the earth (vertical loop).The loopmay also be laid on the bottom of a nearby lake or pond (lake loopor pond loop). Your GXScirculates liquid (the heat transferfluid) through the loopand to theheat pumplocated inside the heat pumpextracts heat from the Ground and distributes the heatcollected from it throughout thehome. The chilled liquid is pumpedback into the loopand, because it is colder than the Ground , is able todraw more heat from the surroundingsoil.

8 These loopsare often referred to collectively as a closed loop, as thesame liquid circulates through theclosed system over and over again. Each of the Ground -coupling systems already described utilizes an interme-diate fluid to transfer heat between the Ground and the refrigerant. Use of an intermediate heat -transfer fluid necessitates a higher compressionratio in the heat pump in order to achieve sufficient temperature differences in the heat -transfer chain(refrigerant to fluid to earth). Eachalso requires a pump to circulate water between the heat pump andthe Ground loop. Direct-expansion systems remove the need for an intermediate heat -transfer fluid, thefluid-refrigerant heat exchanger andthe circulation pump. Copper coils are installed underground for a directexchange of heat between refrigerantand Ground . The result is improvedheat-transfer characteristics and ther-modynamic performance. However,the systems require a large amount of refrigerant and, because the groundis subject to larger temperature extremes from the direct expansion 3A Buyer s Guide forResidential Ground SourceHeat Pump SystemsIntroduction to GeoExchange Systems4A Buyer s Guide forResidential Ground SourceHeat Pump Systemssystem, there are additional designconsiderations.

9 In winter heating operation, the lower Ground -coil temperature may cause the groundmoisture to freeze. Expansion of theice buildup may cause the Ground tobuckle. Also, because of the freezingpotential, the Ground coil should notbe located near water lines. In thesummer cooling operation, the highercoil temperatures may drive moisturefrom the way is to pump Ground wateror well water directly through the heat pump. A GXS that uses groundwateris often referred to as an open-loopsystem. The heat pumpextractsheat from the well water, which is usually returned to the Ground in a return well. To run an open-loopGXS, you need two reliable wells withwater that contains few dissolvedminerals that can cause scale build-upor rust over the long term, as it ispumped through the heat pump sheat GeoExchange System (Cooling Mode)5A Buyer s Guide forResidential Ground SourceHeat Pump SystemsResidential GeoExchange System (Heating Mode)In both cases, a pump circulates liquidthrough the loopand the heat heat pumpchills (or collects theheat stored in) the liquid when it isbeing used as a Source of heat , andcirculates it back through the loopto pick up more heat .

10 A system for a large home will require a larger heat pumpand Ground loop, with a circulation pumpto the GXShas taken the heat energy from the Ground loopand upgraded it to a temperature usable inyour home, it delivers the heat evenlyto all parts of the building through adistribution system. It can use eitherair or water to move the heat fromthe heat pumpinto the home. Forcedairis the most common distributionsystemin most parts of Canada, although a hot-wateror hydronic systemcan also be used. Forced-Air SystemsA heat pumpin a forced-air GXSusesa heat exchangerto take the heat energy from the refrigerantto heatthe air that is blown over it. The air isdirected through ducts to the differentrooms in the home, as with any forced-air fossil fuelor electric furnace. Theadvantages of a forced-air GXSare as follows: it can distribute fresh, outside airthroughout the home if it s coupledwith a heat recovery air exchanger; it can air-condition the home (by taking the heat from the air inyour home and transferring it to theground loop) as well as heat it; and it can filter the air in your home as it circulates through the GXS is designed to raise the heat of the air flowing through the heatpumpby between 10 and 15 C; fossil fuelor electric furnaces are designed to raise it by 20 to 30 difference means a GXS mustmove more air through the home todistribute the same amount of heat asa conventional furnace.