EARTH ENERGY SOCIETY OF CANADA
Société canadienne de l'énergie du sol

1. Is there a national or local standard for the design and installation of an EE system?
Design and installation are covered under national CSA standards C447 (commercial) and C445 (residential). As of March 2002, both applications are covered under the CSA C448 standard. EESC is not aware of any mandatory provincial regulations pertaining to EE systems, although some municipalities or regulatory agencies may have guidelines or rules which have an impact on the design or installation of EE systems.

2. How does an EE system work?
Solar energy from the sun is absorbed by the earth. A buried pipe (loop) circulates a fluid (usually ethanol or methanol or other approved fluid) that absorbs this solar heat from the ground and conducts it into the building, where a compressor is used to transfer the heat into warm air (or warm water) and then distributed throughout the building. It is more efficient and environmentally superior to ‘transfer’ heat than to ‘create’ it through combustion.

3. How can an EE system provide both heating and cooling?
In winter, the system extracts heat from the ground, which is converted to warm air (or water) for space heating, water heating or radiant floor heating. In summer, the compressor puts heat from the building into the loop fluid, and this heat is ‘rejected’ into the ground outside to provide cooling for the structure.

4. How does an EE system use solar heat to cool a home?
Cold is the absence of heat. In summer, heat from the building is transferred into the fluid used in the loop (by means of a compressor) and, as this fluid circulates, the heat is rejected (discharged) into the ground around the loop pipe. By transferring heat out of the building, this provides cooling and dehumidification.

5. How does the ground provide heat in winter?
The majority of solar radiation that strikes the earth is absorbed into the ground, and this heat is transferred into the building during the winter.

6. How is heat transferred between the ground and the building?
As a fluid is circulated through the buried pipe, it attracts heat from the surrounding ground; the further the fluid flows, the more heat it can extract. When the warm fluid returns to the compressor, heat is taken from the fluid and transferred to the heat pump, where it warms air prior to circulation throughout the building. In summer, the compressor transfers building heat into the loop fluid, which then dissipates heat into the ground as it circulates, and returns to the building in a cooled state.

7. How can an EE system heat both air and water?
The solar heat that is transferred out of the ground can be used either to warm air (for use in a forced air distribution system) or to heat water (for drinking or service applications, or in radiant heating or swimming pools).

8. How does the EE system extract heat from frozen soil?
The loop is buried below the frost line, and insulation is used to protect any section that may rise above the frost line (eg: as the pipe enters the building) to avoid freezing in winter.

9. Can an EE system be used for anything other than heating and cooling a building?
Twenty percent of the average energy demand in a residential home is for water heating, and most units include a component to heat water for potable or sanitary use. Heat pumps can also be used to dehumidify indoor swimming pool areas, by controlling condensation with a minimum of ventilation and using the recovered heat in the main heating process.

10. What happens if an EE system tries to extract too much heat from the ground?
When the loop cannot obtain sufficient heat from the ground, most systems include a back-up electric element to provide supplemental heat. If the demand for heat is higher than the combined supply from the outside loop and the electric backup, most systems will shut down.  Note: the backup electric system continues to provide heat until the problem is fixed.

11. Can an EE system provide heat recovery ventilation?
Some units integrate a HRV unit that can provide fresh air and enhance building comfort, and offer enhanced defrosting without creating negative pressure inside the building.

12. Is the compressor in an EE unit the same compressor as in a refrigerator?
A refrigerator is designed to cool food by extracting heat from the package and transferring the warm air into the kitchen. An EE system can be reversed to provide cooling or heating, depending on the season. There are numerous compressors on the market, all of which use the same general principles, although the specific models used in an EE system are different from the kitchen appliance.

13. What makes an EE system different from conventional heating and cooling systems?
Most space heating and water heating in Canada are provided by combustion of natural gas, oil or propane, or by electric resistance, while most cooling is provided by electric air conditioning. An EE does not use combustion to make heat; it simply transfers solar heat from the ground at very high efficiency. This lack of combustion makes an EE system the best choice from an environmental standpoint.

14. Do EE systems have outdoor units?
The ground loop is buried in the soil and enters the building through an underground penetration. There are no visual components outdoors.

15. Does an EE system require separate ground loops for heating and cooling?
In Canada, an EE unit is used more for heating than for cooling, and a reversing valve can be switched between seasons to reverse the flow of the loop fluid and the operation of the heat pump. The system design may be over-sized for the second application, but that means the unit cycles less frequently.

16. Can an EE system work with a diesel generator?
The generator must be of sufficient capacity and have a constant voltage, to meet the electrical demands of the heat pump operation, including circulating pump for the loop and distribution pump for the hot air.

17. What is the difference between an EE and an air-source heat pump?
An air-source system is a similar concept to an EE system, but it extracts heat from outside air instead of from the ground. Winter air does not contain much latent heat, and the efficiency of an air-source unit drops significantly when outside temperatures drop below 0oC. The compressor in an air-source unit is located in the outdoor compartment, where it is noisy and exposed to weather elements. By comparison, an EE system is more efficient due to higher ground temperatures in winter, and the absence of any outdoor equipment makes an EE system quieter, more aesthetically pleasing and longer lasting.

18. Can EE systems be used in commercial or industrial buildings, or in apartment or school?
Research conducted for NRCan indicates that these applications are very cost-effective and offer high reductions of greenhouse gas emissions. Often, these applications offer a more balanced load profile than a residential home and, therefore, are less expensive for the heating or cooling supplied. More than half the EE systems installed in Canada are used in these applications.

19. Can heating and cooling occur simultaneously in the same building?
Each heat pump unit can perform only one function at a time, but a larger building (with more than one unit) can provide heating to one spot and cooling to another. This is a common application in schools and other institutional facilities, which have a diverse load. The practice also increases the efficiency of the overall system because the heat removed from room A can be transferred to room B, reducing the need for the ground loop to provide both heating and cooling (and thereby reducing the total installed cost).
 

Design

1. What size of heat pump is required?
A heat loss - heat load assessment will determine how much heat the building requires. The installed heat pump and supplementary backup unit must meet this load, subject to the conditions in the CSA standard. The quantity of loop must be consistent with the size of the heat pump. On average, a 4 ton unit will be sufficient for a 1,700 ft² home.

2. Is the EE system designed to provide 100 percent of building heat and water heating?
A heat loss calculation will determine how much heat is required for both applications, but most systems are sized to meet less than the full design load and rely on an electric backup heater to provide supplemental heat on very cold mornings during the winter. In all cases, full cooling load can be met by a system.

3. Is there a national or local standard for the design of an EE system?
Proper design is covered under national CSA standards C445 (residential) and C447 (commercial). As of March 2002, both applications will be covered under CSA C448. We are not aware of any provincial regulations, while some municipalities or other regulatory agencies may have guidelines or rules pertaining to the professional installation of systems.

4. What is an open loop?
One pipe is used to take water directly from a lake or river, or an underground well or aquifer. The water is circulated through the heat pump to extract the heat, and a second pipe is used to return the water to the same source. Standards dictate that the amount of water extracted cannot impact negatively on the ecosystem, and consideration must be given to discharge areas to avoid impacts (eg: if slightly warmer water is discharged into a lake during summer, the discharge should not be located near sensitive aquatic life).

5. What is a lake loop or river loop?
The pipe is anchored to the bottom of a water body of sufficient depth, and extracts heat directly from the water. The pipe must be weighted to avoid shifting, and must be protected at the point of entry into the lake to avoid being severed by ice movement in the spring. The position is determined to avoid damage from boat anchors. The amount of heat extracted from the water is so low and diffuse that there is no ecological damage to marine life or aquatic systems, even in the immediate vacinity of the loop.

6. What is a vertical closed loop?
A drill is used to bore a cavity, into which a section of looped pipe is inserted and sealed according to provincial regulation. This configuration is the most efficient, since it extracts both solar heat from near-surface soil, as well as magmatic heat from deeper areas. This option is used when surface property is limited.

7. What is a horizontal closed loop?
A trench of at least 4 feet depth is dug. At the bottom, the high-density polyethylene pipe is placed and the trench is carefully back-filled to avoid air pockets or damage from sharp rocks. There can be from one to six pipes placed in each section of trench, subject to appropriate spacing to allow for thermal separation. The pipe does not have to be perfectly level.

8. Why is there lack of consensus over the issue of system sizing?
Most consumers will receive excellent performance and savings with an EE unit that is designed to provide 70-75% of the total heat loss for the building. When ambient temperatures are above the design balance point, the EE unit will provide all heating required; only when outdoor temperatures drop below that point does the EE unit require supplemental heat from an electric resistance heating element inside the unit. Most outdoor winter temperatures are above the balance point, and the EE system can provide 95% of the load if the unit is sized to 70%. Some dealers prefer to install a system that meets 100% of heat loss; this eliminates the need for supplemental heating but increases the cost of installation (more pipe is required).

9. What is the difference between a closed loop and an open loop?
A closed loop is a continuous pipe that circulates a fluid (often with an antifreeze mixture) to extract heat from the surrounding soil or water. An open loop is, essentially, two pipes: one to suck in water that is moved through the heat pump to transfer heat, the other to take the cooled water and discharge it to the appropriate location, usually downstream from the first pipe.

10. Is ductwork for air required?
An EE system can heat either air or water. If air, ductwork is required to circulate the warmed air throughout the building. Due to the low temperature rise of an EE system, the volume of circulated air is higher than a combustion furnace and, therefore, the ductwork must have a higher capacity in cubic feet per minute.

11. Is there any difference between a ground loop and a water loop?
Both loops extract heat from the surrounding earth (soil or water) for transfer into the heat pump. Temperature changes in water temperature can be more dramatic than changes in soil temperature (eg: if your water loop were located near a glacial stream) and water levels are more prone to change (eg: drought conditions).

12. What are the options if there is insufficient room for a horizontal loop?
The loop can be installed in a vertical borehole(s). An open-loop system may be possible if there is sufficient water. The use of coiled loop pipe or numerous pipes in the same trench may be a feasible option.

13. What are the components of an EE system?
There are three basic sections: energy supply comes from the ground loop (or vertical or lake loop); the conversion of heat occurs in the heat pump and compressor; and the warmed energy is delivered through the circulation system (ductwork or in-floor radiant heating).

14. Can an EE system heat a building without supplemental heat?
A system can be designed to provide 100% of heating needs on the coldest days in northern Canada, but the cost to install such a system would be excessively high. A system designed to provide 70% of a calculated heat load is the optimal sizing if there is a supplemental heating element, but there were past errors in calculating the heat loss and, consequently, some systems were under-sized. The new CSA standard for installation (C448) has been revised to overcome this deficiency.

15. How long should the buried ground loop be?
The length of pipe depends on two factors: the amount of heat required in the building (the more heat required, the larger the heat pump and the longer the loop must be) and the thermal transfer characteristics of the soil (dry light soil with entrained air can require three times the amount of loop to provide the same heat as wet, packed soil). Design software will calculate the amount of pipe for a specific site. An industry rule of thumb is that an average home requires a four-ton unit, which requires 400-500 feet of horizontal loop or 300-350 feet of vertical borehole for each ton (up to six pipes can be installed in a horizontal trench if spaced properly).

16. Are there advantages of an open-loop system over a closed-loop system?
Open-loop units usually are less expensive to install (no need for trenching or drilling) and are more efficient (the heat in the supply water is transferred without the need for antifreeze). Closed-loop units offer more security of supply (less chance of constriction of the water supply) and have no environmental impact. Often, loops operate at a lower cost than open systems due to lower pumping power required.

17. What is the link between size of heat pump and length of loop?
The higher the heat load (demand for heat), the larger the heat pump. The larger the heat pump, the longer the loop required.

18. How much power does an EE system consume?
The system requires electricity to operate the loop pump, the compressor and the circulating fan (in forced air distribution). It also uses electricity in the backup mode to deliver sufficient heat on very cold days, and requires power throughout the year to operate the water heating component. The amount of power used will depend on the size of the unit, operating times and sizing considerations, but an average residential unit would require 11,000 kWh per year, which represents an annual cost of $935 (based on 2001 retail prices).

19. Can any pond be used as the heat source?
The body of water must be large enough to contain sufficient latent heat to meet the demand of the building. The larger and deeper the better, but stagnant or glacier-fed bodies are not feasible.

20. Can an EE system be used for radiant floors or hydronic heat?
The heat pump can produce water that is hot enough for use in these applications. In most cases, it is not warm enough to be used in old-style under-the-window radiator systems.

21. Where can the ground loop be located?
The CSA standard does not allow pipe to be placed near septic tanks or hydro lines, and must be a minimum distance from neighbouring property lines.

22. How does heat circulate if the building has no ductwork?
Without ducts, the only option is to circulate heated water through a radiant in-floor configuration, or small fan coil units.

23. How much groundwater does an open-loop system require to operate?
Depending on the heat load of the building, most units require 8 to 12 gallons per minute of water; more if the unit is heating potable / service water at the same time.

24. If the entering water temperature drops, what is the impact on the EE system?
Lower water temperature (either direct from a lake/well or cooler fluid returning in a closed loop) reduces the available heat that can be transferred to the building; ie: the building gets colder. If the entering water temperature drops below a set temperature, the EE system will shut down.

25. What should be done with discharge water from an open-loop system?
The CSA standard and provincial / local regulations require that the water be returned to source after passing through the heat pump. The system removes only a small amount of heat, so the water discharged is not classified as sewage. Care must be exercised to ensure that open-loop systems protect the environment to the greatest degree possible and comply with all laws, standards and regulations.

26. Will my existing ductwork function with this system?
Your contractor can determine the ductwork requirements for your system and identify if modifications are needed.

27. Will baseboards work to circulate heat?
Baseboards can only conduct electricity. An EE system requires either ductwork to circulate warm air or radiant in-floor coils to circulate warm water.

28. Does an EE system require additional insulation in the building?
The lower the demand for heat, the smaller the heat pump and the lower the installed cost. Insulation, along with any energy management or conservation technique, is always the best first step in any heating system.

29. What will cause an EE system to fail?
The main reason for system failure is under-sizing in design, which means that the building requires more heat than the EE system can reasonably provide, and the resulting strain causes a component to fail.

30. Why is there supplemental heating?
To reduce installation costs and provide better performance, an electric resistance heating element is included in unit to boost the heat during extremely cold temperatures. A fossil fuel furnace can also be integrated.
 

Installation

1. How deep should a loop be?
The CSA C448 standard requires that horizontal loops be buried at least 4 feet below surface. The deeper the depth the better, as thermal stability increases with depth. Many provinces demand the use of trench scaffolding if depths exceed 6 feet, which imposes a cost. Vertical boreholes have no limits on depth, although an average depth is 100-200 feet.

2. Is there a national / local standard to govern the installation of an EE system?
Installation is covered under national CSA standards C445 (residential) and C447 (commercial). As of March 2002, both applications will be covered under CSA C448. We are not aware of any provincial regulations, while some municipalities or other regulatory agencies may have guidelines or rules pertaining to the installation of systems.

3. How far apart should trenches and vertical boreholes be spaced?
Trenches are usually spaced 8-10 feet apart, while boreholes are spaced 10-15 feet apart.

4. Can the ground loop be installed by someone other than the contractor?
Most contractors prefer to retain control over the entire job to ensure compatibility of all sections, but the digging of the horizontal trench (and backfilling) is one area that could reduce costs if done under the guidance and direction of the installing contractor.

5. Can a homeowner install an EE system?
It is recommended that a qualified and certified contractor be used to design and install the system. If a homeowner wants to save money and has access to a backhoe, the contractor may provide details on where to trench on the property, and when to backfill after the loop is installed.

6. How deep should the vertical borehole be drilled?
The deeper the better, but there are cost constraints. Most residential boreholes are 75-100 feet, but can be as deep as 300 feet.

7. How deep should the ground loop be installed?
The CSA C448 standard directs that the minimum depth is 4 feet; the former 445 standard required 2 feet. The objective is to install the loop as far below the frost line as possible. Many provinces require safety measures when a trench is more than six feet deep, so most contractors do not exceed that depth in order to reduce costs.

8. Are there any concerns with joining sections of underground pipe?
The high-density polyethylene pipe is socket fused (basically, melted together with a high temperature tool), which makes the joined plastic section more solid than the original resin. If done by a certified fusion contractor, there is virtually no chance of breakage or separation under normal conditions.

9. How many pipes should be installed in a trench?
From one to six, depending on design considerations and the thermal characteristics of the soil.

10. What spacing is required for the ground loop?
Each pipe extracts heat from the nearby soil, so separation should be as wide as possible. The CSA standard demands at least 10 feet between sections of loop, which can be reduced under certain conditions.

11. Does an EE system use a setback thermostat?
A system relies on a constant, low level of temperature for the building, and any sudden increase in heat demand will cause the supplemental backup heating unit to activate. Setback thermostats are not recommended for use with an EE system.

12. Is it possible to make a mistake when installing the ground loop?
It is unlikely that a certified loop installer would make any mistake sinece he/she is trained to fuse sections of loop. The CSA standard requires that a system be tested to a pressure above normal operating levels, to determine if there are any leaks or problems which can be corrected immediately.

13. Is there a concern with poor-quality water in an open-loop system?
In a closed-loop system, the water must be of good quality and meet the specifications of the heat pump manufacturer and the supplier of the anti-freeze solution with which it is mixed. In an open-loop system, some chemicals and minerals in the water may not be compatible with the heat exchanger. An analysis of the water should be performed before purchase to determine which model of exchanger is required. If the water content changes over time, this may have a detrimental impact on the system.

14. Can an EE system be added to a fossil fuel furnace?
A dual system can be added to an existing furnace to provide a dual-fuel heating system, where the heat pump is the main source of heating and the combustion furnace provides the supplemental heat.

15. Is an EE systems difficult to install?
The ground loop can be difficult to install, depending on rocks, physical obstructions and topography. The interior heat pump is easy to install, and can be located in areas without proper ventilation (there is no combustion, so no need for exhaust). Most units are easy to install, especially when they are replacing another forced-air system. The air distribution may be difficult in a retrofit installation.

16. Will an EE loop affect a lawn or landscape?
The only impact will be a period of settling for soil that is placed back in the trench. This visual evidence takes one year to settle.

17. Can an EE system be located in a septic bed to take advantage of the heat?
The CSA standard specifically bans locating a ground loop near septic systems to avoid retarding the microbial action to decompose sewage. Grey water from the building can be used in some situations, if that collection unit is separate from the septic system.

18. What heat transfer fluids are permitted?
The anti-freeze that is used in a closed-loop system must be approved by provincial authorities and acceptable to the heat pump manufacturer. Methanol and denatured ethanol are the most common fluids used (methanol is not approved for use in Ontario). The fluid must be mixed with water in accordance with instructions, usually on a 4:1 ratio of water-to-chemical.

19. Can I install an ground heat exchanger myself?
It is not recommended. In addition to thermal fusion of the pipe, drilling and trenching are procedures best handled by licensed professionals. Nonprofessional installations may result in less than optimum performance, which could cancel out anticipated savings. Also, warranties are usually void if the system is installed by a non-authorized dealer.

20. Will trees or plants affect ground temperature or the efficiency of an EE system?
No. Systems are installed away from trees to avoid damage to root systems when digging the trench.

21. How long does an installation take?
Depending on soil conditions and the length and depth of pipe, a typical residential system can be installed in two days.

22. What laws apply to open-loop installations?
The CSA C448 standard contains a number of requirements to ensure that an open-loop unit does not abuse the increasing valuable water resource.

23. Does the capacity of electrical service need to be increased with the addition of a heat pump?
A contractor can advise if an upgrade is required to accommodate the additional electricity required.
 

Performance

1. How efficient is an EE system?
The performance of the heat pump unit is rated by its ‘Coefficient of Performance’ which calculates how much energy is required to transfer heat into a building. Units are tested under the CSA C446, ARI 320, ARI 325 or ISO 13126 standards. In Canada, units cannot be sold if they rate below 2.8 CoP and many units achieve 3.5 or above. If the CoP is 3.5, a system requires 1 kW of electrical energy to transfer and deliver 3,500 W of space heat; this is equivalent to a combustion furnace with an efficiency of 380 percent.

2. How long will the loop pipe last?
The pipe is high-density polyethylene. Most suppliers provide a warranty of 25 years or more.

3. What factors will affect the performance of an EE system?
Common problems for degradation of output in a well-designed system include dirty air filters (clean), air trapped in the ground loop (purge) and declining anti-freeze level (add more). Human error includes mis-set thermostat while natural problems include dropping water table or increasing mineral content in the water.

4. Is an EE system more comfortable than a conventional furnace?
A heat pump moves a large volume of warm air throughout a building, but it is at a lower temperature than a combustion furnace, resulting in an even and steady delivery with no draughts. The lack of combustion and higher air circulation of an EE system results in less indoor air contamination and lower pollution levels, as well as reduced humidity buildup.

5. What happens when the outdoor temperature becomes very cold?
Although the outdoor ambient temperature can drop significantly and quickly, the temperature of the ground below the frost line remains constant and it is from this level that an EE system extracts heat. In the worst case scenario where the outdoor temperature drops for a prolonged period and there is an extraordinarily high demand for heat, the supplemental heating unit on the EE heat pump will provide the difference in heat.

6. Does the quality or quantity of water have any bearing on performance?
Water that comes directly from a lake or a well must meet certain levels for temperature and flow rate, and must contain few minerals. The CSA standard requires an official water well log to ensure that the yield is sustainable, and an analysis should be done to determine if the water contains any chemicals or metals that could damage the heat exchanger or other component.

7. Can an EE system be diagnosed by long distance?
Some manufacturers have incorporated electronic measurements to provide diagnostic capability over the telephone. In some cases, this allows the system to be re-set without a service call.

8. How safe is an EE system?
An EE system is considered to be one of the safest heating/cooling systems available. No combustible fuels are used, which eliminates any chance of explosion, and it also reduces concerns over indoor air quality (IAQ). There are no outside components that can be tampered with or vandalized.

9. What are the options for water heating?
An EE system heats domestic water with a demand unit or a desuperheater. The former gives priority to water heating over space heating, while a desuperheater will heat water only after space heating has been accomplished. The difference depends on the lifestyle of the occupants.

10. How durable is the pipe in the ground loop?
The CSA standard allows only high-density polyethylene pipe, with the three most common diameters being 0.75", 1.0" and 1.25". Sections of pipe are heat fused and many suppliers offer a warranty of 25 years. The resin in this pipe is the same used in the pipe used to transport natural gas. This plastic does not degrade under sunlight and is warranteed not to fail.

11. Does an EE system come complete with all components?
Most units include all pumps and controls, but it may be the responsibility of the contract to obtain some individual components. All non-packaged components must be compatible with the heat pump unit, and written documents should demonstrate that the manufacturer allows the components to be used and that their use will not interfere with warranty coverage.

12. Are EE contractors certified?
A number of manufacturers offer training for their authorized contractors that is specific to that brand but, as of early 2002, there is no certification program in Canada. A program was offered by the Canadian Earth Energy Association (the predecessor of the Earth Energy Society) until 1993. There is a program offered by the International Ground Source Heat Pump Association and the Geothermal Heat Pump Consortium in the United States. There are a number of related certifications (for heat loss analysis, ductwork installation, etc) offered by the Heating, Refrigeration & Airconditioning Institute of Canada, among others.

13. Where does water from an open-loop system go?
There are environmental regulations, which govern how the water used in an open-loop system can be returned to the ground. A return well is acceptable, as long as the water is returned to the same aquifer or level of water table. A discharge pit is also acceptable, as long as local regulations and conditions are considered in the design. 

14. Are all pipes straight?
There are two coiled loops on the market, called the Slinkey and the Svec Spiral, which require less trenching and reduce installation costs. The installation of coiled pipe is more demanding than straight pipe, and back-filling must be done properly.

15. How is the CoP efficiency rating determined?
Units are tested under laboratory conditions, with a set temperature for the entering water. The total heat output and the electricity required to operate the entire system are the two variables used to determine the CoP rating for each unit.

16. What are the environmental benefits of EE?
Due to the use of solar energy and the high efficiency of the transfer technology (the heat pump), an EE system can reduce emissions of CO2 and other greenhouse gas emission compared with combustion furnaces. The lack of combustion means a chimney is not needed.

17. Is there a lot of noise from an EE system?
The compressor, pump and blower are all sound-insulated. The CSA standard requires a heat pump to be placed on top of an acoustical air pad to eliminate vibration noise and there must be sound dampeners where the heat pump connects to the ductwork. The system is one of the quietest options on the market.

18. Can a large number of EE systems create ecological problems?
Each system is designed to ensure sufficient heat from the property in which it operates, and there is no potential to “freeze the globe” or to disturb natural habitats or ecosystems. Systems use renewable energy to heat a building, and benefits to the environment increase with the number of units installed, when compared with conventional fuel-based heating units.
 

Warranty / Service

1. What is the life expectancy for an EE system?
The technology has been used in many countries for more than 20 years, and a properly-maintained system should last for 25 years or more. No components are exposed to harsh outdoor elements, so deterioration due to weather or physical damage is avoided. There are few moving parts to minimize maintenance.

2. What is the warranty on an EE system?
A consumer should request a copy of both the manufacturer's warranty and the contractor's warranty, in writing. Most heat pumps come with a one-year general warranty and a five-year warranty on the compressor, and extended warranties are available. The polyethylene pipe carries a warranty of 25 years or more. Contractors offer a workmanship warranty.

3. Are all heat pumps the same?
All units transfer solar energy from the ground into a building, where a compressor converts that energy into warm air or warm water. Options on various models include two-speed compressors, demand water heaters, quad functions and electronic diagnostics, among others. Units should be certified to ISO performance levels (formerly CSA or ARI rating), to make the COP the key variable among different manufacturers.

4. What component is most likely to fail?
The 'protected' nature of an EE system makes it less likely to fail than any other system. Utility line spiking and other external problems can damage electronic contacts or circuit boards (but these spikes would also harm computers, televisions and other systems). Like a refrigerator, the compressor has the highest risk of failure and is the most expensive component to replace. Most units carry a warranty of at least five years.

5. What maintenance must an owner perform?
Optimal performance is achieved when system air filters are clean, and a homeowner should change / clean filters (except electrostatic units) at least once a month. All other maintenance (system purging, refreshing of antifreeze, etc) should be performed by a qualified contractor on a regular basis.
 

Costs / Savings

1. What is the cost of an EE system?
There are two costs: installed (or capital) cost, and operating costs. There are too many site-specific variables to quote the first cost for a system, but estimates to install a complete system (including ground loop and heat pump) range from $10,000 to $20,000. This may be higher than the cost to install some combustion furnaces but, in all cases, the annual operating costs for an EE system that provides space heating, water heating and space cooling, will be lower than the cost to operate any other furnace of any efficiency level for the same functions.

2. What is the payback period?
Payback is a method of calculating the time needed to recover any premium cost for an EE system over another heating and cooling system that is being considered. The process combines the cost to install and operate both systems over a period of time. For a residential EE system, the simple payback averages from four to seven years.

3. What additional costs are expected with an EE system?
There may be an installation charge for electrical work or upgrades to the circuit breaker, addition or modifications to interior ductwork, water hook-up or lawn restoration costs. These costs are estimated in advance by the contractor. Servicing or maintenance contracts may be included in the purchase price or are an additional cost.
 

Issues Specific to Commercial / Institutional Systems

I1. Is a professional engineer required for an EE installation?
Most non-residential facilities are designed by architects and installed by engineers, and it is common practice for building owners to use registered professionals who offer liability protection. Engineers would be expected to comply with the provisions of the CSA C448 standard on the installation of EE units in larger buildings.

2. Is there any difference in design or installation of a non-residential unit?
There are few differences in the installation of the loop for non-residential facilities, but there are significant differences in the design of heat load and cooling load profiles.

3. Can an EE system heat and cool at the same time?
Each unit has one only compressor, and can only heat or cool at any given moment. ICI systems require more than one unit, and the greater the number of units (ie: the larger the system), the more balanced the load. For example, schools can use one unit to extract heat from a gymnasium to provide cooling, and transfer the heat to the unit serving the library, where heat is required. This 'internalizing' of the load allows the demands on the ground loop to be reduced, either allowing the ground loop to rejuvenate more quickly or to reduce the installed costs.
 

Environmental Issues

1. What are the environmental benefits of an EE system?
By transferring solar energy from the ground into a building, there is reduced need for generation and transmission of electricity, or less need to drill and transport fossil fuels, with an accompanying reduction in the emission of pollutants at all stages. Data from governments in both Canada (Natural Resources Canada) and the United States (Environmental Protection Agency) indicate that EE systems are the most benign space conditioning technology on the market today in terms of environmental impact.

2. Does an open-loop system cause environmental or ecological damage?
Water is taken from a lake or a well, circulated through the heat pump where the temperature is reduced slightly, and then discharged into the same source to complete a cycle. There is no indication that a minor temperature change has any adverse effects on the environment, although due regard to sensitive aquatic areas is provided at point of discharge.

3. Does a closed-loop system cause environmental or ecological damage?
The pipe used is a high-density polyethelene plastic that has no environmental impact on the surrounding ground. It is virtually impossible to destroy a ground loop under normal conditions but, in an extreme case of accidental cutting of the pipe, the drop in system pressure will cause the unit to stop pumping. if any fluid does leak before system shutdown, the anti-freeze is (usually) ethanol diluted to 20 percent of volume, and would have a minimal impact on the surrounding ecosystem.

4. Are compressors environmentally damaging?
Compressors use a refrigerant (often referred by a trademark name 'freon') in the pressure cycle, and industry specifications assume that all compressors leak a small amount over time, with a detrimental effect on the ozone layer. The Montreal Protocol was a global treaty to mandate a transition from refrigerants that were negative, to more benign mixtures, and EE systems use compressors with refrigerants that offer the lowest possible impact on the environment. Most units currently use R22, but some units now offer 410A refrigerant.

5. What is the ecological impact from temperature extraction?
A system can not drop the temperature of the soil below freezing. There is no adverse impact.
 

Definitions

1. Co-efficient of Performance:
CoP is the measure of performance that illustrates how much electrical energy is required for each unit of thermal energy. A CoP of 3.0 means that 1,000 watts of power is consumed by the compressor, pump and blower, to deliver 3,000 watts of heat energy to the building. The 2 kilowatts of ‘net’ energy is the solar energy that is transferred into the building. In Canada, the federal Energy Efficiency Act states that closed-loop units must have a CoP of at least 2.8 and open-loop units must have a CoP of at least 3.2.

2. Sizing:
A heating system must meet 100% of a building’s heat loss, but an EE system uses an electric resistance heating element to supplement the solar energy transferred from the ground. A residential unit that is sized to 70% of building load will provide 90% of the heat, with the supplemental electric heater providing the other 10%.

3. Balance Point:
The outdoor temperature above which an EE system can provide the entire heating requirement of the building; usually -10oC. When the outdoor air temperature is above this balance point, the EE system cycles on and off to satisfy the interior demand for heat. When the outdoor air temperature is below this balance point, the EE system runs continuously and invokes the supplementary heater (also called auxiliary or backup or second stage heater) to meet the demand.

4. Sink:
The use of soil or water to accept heat that is rejected from the building (to provide cooling).

5. Heat Source:
The use of soil or water to provide heat for the system.

6. Auxiliary / Emergency Heat:
A heat pump is designed to provide full heat to a building until the outdoor air temperature drops below the design balance point, at which time the auxiliary or supplemental or backup or second stage electric heating element is activated. Emergency heat is provided by the same electric element in the unlikely case of failure of any component that shuts down the heat pump operation.

7. Heat Loss:
A calculation of the total amount of heat required by a building, considering insulation levels of walls, ceilings and windows, number of occupants, geographic location, soil type and many other factors. The process also calculates the heat gain of the building to determine the summer cooling load.

8. British Thermal Unit:
A measure of the heat required to raise the temperature of one pound of water by one degree Fahrenheit. This is an imperial measurement; aapproximately 12,000 BTU of capacity equals a one ton heat pump.

9. Air Distribution:
After the heat pump has converted the solar energy to warm air, the unit distributes the air throughout the building by means of ductwork.