Geothermal System Q's & A's
Q: Why are Geothermal Systems so expensive?
A: The equipment costs close to the same as a quality name brand high efficiency furnace and air conditioner. The additional cost is in the installation. An open loop usually requires less capital investment than a closed loop system if the well and discharge are already existing.
A horizontal loop requires excavation equipment and pipe installation.
A vertical loop requires drilling and excavation equipment and pipe installation.
Special tools are required to fuse, (weld) the plastic pipe together underground.
Special flushing and charging equipment is required to clean, air purge and freeze protect the earth loop once it is connected to the geothermal unit.
Ductwork is somewhat larger than with other furnaces because geothermal systems move about 40% more air than fossil fuel systems of similar heating capacity.
Q: What are the heat exchanger loop pipes made from?
A: Geothermal earth loops are made from High Density Polyethylene, (HDPE) pipe. The circuits are either 3/4" or 1 1/4" diameter and headers are either 1 1/4" or 2" diameter.
The resin is PE 3408 having a cell classification, 345564 or 345434 per ASTM Standard Specification D3350, certified as being in accordance with CSA Standard B 137.1.
This is the specification referred to in CSA 445 and CSA 448 and thus is mandated by Canadian Building Codes.
CSA Certified geothermal pipe will always carry CSA Certification on the pipe itself. If it does not say CSA Certified for Geothermal Systems on the pipe, the pipe is not certified for use in a Geothermal System.
Q: What happens if there is a break in the pipe?
A: All coils of pipe are inspected for integrity before installation in the ground. Great care in handling the pipe must be taken during the installation.
As mentioned, all underground connections in an earth loop are fused together using a 510° F. fusion tool. A correctly installed fusion joint has a burst pressure of approximately 1,000 psi., higher in fact than the burst pressure of the pipe itself, (around 400 psi).
During an installation, if a fused joint is at all questionable to our installers, they are instructed to cut it out and replace it before loop burial.
Just Geothermal Systems pressure tests all earth loop installations.
With the above attention to quality and by using CSA Certified earth loop pipe only, the likelihood of a loop failure due to a pipe manufacturing defect or joint failure is extremely low.
As far as we know, (according to our suppliers), there have been no pipe failures of CSA Certified Geothermal Pipe in Canada in at least the last 13 years.
Pipe breakage during the installation of a new deck or a swimming pool or some other sub-surface installation has occurred but infrequently. Just Geothermal Systems always provides the owner with an installation site plan locating the earth loop on the plan for future reference.
If a leak does occur it can be be found by pumping out the loop fluid and pressurizing the loop with helium. Helium is a very light, inert and harmless gas. It is the second smallest molecule known to science. It is therefore able to rise through the soil where a "helium sniffer" can detect the leaking spot fairly closely. Horizontal loops are usually easily repaired. A leak in a vertical loop down inside a bore hole would require abandonment of that borehole, replacement and splicing the new vertical heat exchanger in to the circuit.
Q: What are my hot water heating options?
A: Most systems utilize a desuperheater to transfer a small amount of excess heat in the system to a standard electric Domestic Hot Water, (DHW) tank. Annually a desuperheater can provide 50% to 60% of the hot water requirements for a family of 4 or 5.
Demand hot water heating, (a.k.a. 100% hot water heating or a triple function machine), requires that a second condenser be built into the unit for hot water heating. This feature is intended as a heat source for either partial RFH, (Radiant Floor Heating), or for pool or spa heating.
As a general rule we do not provide 100% DHW heating using this method. Geothermal systems are installed mostly in rural areas where the house uses a well for domestic water supply. Well water is prone to high mineral content which will precipitate out and plug up a hot water condenser sooner or later. A geothermal system is primarily a space heating system or furnace. A plugged condenser could leave the owner without space heating from the heat pump unit necessitating the use of back up heat until a repair is made.
Water to water systems are dedicated water heaters, usually used to heat large RFH systems and or hot water fan coil systems. They can be reversible to provide chilled water for cooling as well. A small water to water system of one ton capacity would be an acceptable DHW heater in conjunction with a separate unit for space heating and cooling.
Q: I've heard that heat pumps blow cold air is that true?
A: A complaint associated with air source heat pumps in the past that is not relevant to Geothermal Systems. Geothermal systems are designed to provide air temperatures between 95° F and 100° F. This is very close to body temperature. Most customers find this extremely comfortable as the air is neither hot or cold. Humidity levels will stay higher than with some other systems too because there is no combustion taking place and the air is not dried out.
Q: Are log homes suitable for Geothermal?
A: Most definitely, in fact it is the preferred and recommended heating method by many log home builders. The lack of combustion in a Geothermal System means that logs do not dry out as much as with a fossil fuel system.
Q: What are the maintenance issues?
A: Like most heating equipment today, Geothermal Systems contain sophisticated electronic components. Regular annual furnace care should be planned for, for preventative reasons.
Dust, clean and inspect annually all compressor contactors and fan relays as they experience the most wear and tear due to high current surges when components start up. The life expectancy is 5 to 7 years but they are relatively inexpensive components.
The air coil can become clogged requiring a cleaning. Just Geothermal always advises the client to purchase a high efficiency filter of some kind. The pleated Space Guard filters are excellent as are some of the better electrostatic and the electronic filter from Dynamic.
A clogged coil can cause excessive compressor oil wear and tear due to high temperatures and pressures. If left running to the limit for a long time, some excessive wear and tear might be placed on the compressor.
Note: Always check and clean your filter every 3 months and inspect the air coil annually.
Occasionally the earth loop may require flushing. Sometimes when filling the system from a well, tiny CO2 bubbles are contained in the water. After some time they may collect and become noisy when the loop is pumped. A slug of air can damage a pump, snapping the impeller shaft. The loop should be checked for this condition at the annual furnace care check up.
Q: Geothermal Systems have a reputation for heating a home inexpensively, just how inexpensive are they to operate?
A: Energy costs vary around the Province from region to region so a truly accurate energy cost picture created today may be out of date by the next month or even the next week.
Q: So how is the consumer to know what a Geothermal System can do for them?
A: From the early eighties, Ontario Hydro was one of many North American utilities that monitored Geothermal Systems extensively throughout the Province. Their conclusion was as follows, "Geothermal Systems are the most energy efficient heating and cooling systems available today" – Ontario Hydro.
It has been proven beyond any shadow of a doubt and independently verified , many many times over that geothermal systems provide homeowners with the lowest operating cost for heating cooling and domestic hot water production. Various publications supporting this fact are available from Ontario Hydro and the Federal Government on-line; some you can link to from this site.
Consumers will see varied savings from Geothermal System installations across Southern Ontario because fuel prices vary so much. For example, there was a in significant difference in the cost of propane between London and Waterloo Region by January and February 2001, when the prices peaked. In London, propane was available for around 66 cents per litre, in Harriston, just North of Waterloo, some customers were reporting the same product costing around 79 cents per litre.
You can't expect fuel suppliers to all charge the same price to deliver fuel, but you can expect their prices to increase when your fuel demand increases in winter – at the time when you need heat the most.
At Just Geothermal Systems, we estimate the cost of heating with fossil fuels, by averaging the per unit cost of the fuel over the entire year. This places our estimates within 10% either way. What is both important to note and remarkable, is the percentage savings a Geothermal System delivers over burning fuel today. Even if our overall energy use estimate turns out to be a little high in the field, the percentage savings remain the same, because we know what it costs for any system to produce a Btu. (British Thermal Unit), of heat. That doesn't change and the way to produce a Btu. is by using a Geothermal System to do it.
Q: How does the energy analysis work?
A: We use a sophisticated energy analysis programme, that utilizes algorithms based upon ASHRAE (The American Society of Heating, Refrigeration and Air Conditioning Engineers), Modified Degree Day Method. This is considered an acceptable way to estimate thermal energy use in small buildings by the engineering community. Our software allows us to estimate energy consumption in small buildings based upon the building heating and cooling loads and local weather data statistics. Once we model the amount of energy it takes to heat, cool and provide domestic hot water for a home for a typical year, it is relatively easy to compare the operating costs of various types of heating systems delivering the calculated amount of energy; a Geothermal System being one of them.
Q: So how could a homeowner determine which type of heating system provides them with the lowest operating cost?
A: A way to illustrate relative energy costs to the consumer is to examine the number of heating Btu's, $ 1.00 Canadian buys.
The formula is as follows:
- Heat Content per unit of Fuel (Btu/unit) ÷ Cost per Unit of Energy ($) x Furnace Efficiency (%)
First though we should explain a little bit about furnaces and furnace efficiencies, to place the matter into context for those new to this subject.
Nominal Fuel Heating Values
According to ASHRAE, fuels we commonly use to heat our homes with contain the following approximate heating values (Btu's) per unit volume. We can only state "approximate values" for fossil fuels, because the exact chemical composition of fuels varies with the well location, and thus the fuel heating value changes a little from area to area. Also published engineering fuel heating value data are based upon combustion at sea level and London is approximately 900 feet above sea level. However, good quality control by the suppliers keeps fuel heating values fairly close to those listed below and for the purpose of a geothermal comparison, any error would most likely favour the combustion appliance.
- #2 Fuel Oil – 36,984 Btu/litre
- Propane – 24,304 Btu/litre
- Natural Gas – 35,315 Btu/cu M.
Adjusting Fuel Heating Values for Furnace Efficiency
The heating values shown above are RAW, or Total Heat Values, representing 100% combustion efficiency. RAW values must be adjusted downward to compensate for the combustion efficiency of the furnace. Today's best furnaces, although much more efficient than years ago, deliver only a percentage of the RAW heat value into the home. Table 1. compares the RAW fuel heating values to the Net Fuel Heat Values delivered by today's high efficiency furnaces. Lost heat goes out the flue or chimney.
Fuel Type #2 Fuel Oil
Propane
Natural Gas
Electricity Fuel Heating Value
Electric furnaces on the other hand are considered 100% efficient as they have no flue. An electric furnace is really just a big toaster that sits in a ductwork air stream, all the heat produced goes into the house. See Table 2.
Fuel Type Electricity
Geothermal System Fuel Heating Values
Geothermal System appear to be more than 300% efficient because they run on electricity and actually deliver more energy to the home than they consume in electricity. See Table 3.
Fuel Type Geothermal
Q: How can Geothermal Systems produce more energy than they consume – this claim sounds too good to be true and you know what people say about that?
A: Yes it does sound somewhat miraculous, but it is not just a claim, it's a well proven fact that geothermal systems deliver more energy than they consume. Once someone understands how the systems work you see that a 350% efficient heating system is really a misnomer
Geothermal Systems are simply an application of the refrigeration technology we are already used to in our homes that is exhibiting a C.O.P. Of 3.5.
Refrigeration systems move heat from one place to another, the result is one part of the refrigerator becomes colder and another part of the system becomes warmer. Just place your hand behind your fridge to experience this for yourself. The heat from inside the ice box is removed by the refrigeration process and rejected into the space at the back of the fridge along with the energy used to do the work, (run the compressor).
If you had a big enough refrigerator and something really big to cool down for 6 months of the year your refrigerator could heat your whole house. This is exactly what a Geothermal System does. It is a large refrigerator that cools down the mass of soil surrounding the pipes buried in your back yard and you can heat your home with the heat rejected from the process.
Q: So how is the Geothermal System producing more energy than it consumes when it's moving heat into the house?
A: A Geothermal System works similarly to a lever or pulley that allows one to move heavy objects with low effort. A pulley has an inherent mechanical advantage; so does a Geothermal System.
One unit of energy (kW.), is used to do the work of operating the compressor to transfer 2.5 units (kW.), of energy from the ground into the house. The one unit of energy used to operate the compressor is contained within the heat transfer process and is added to the 2.5 units of energy extracted from the ground. 3.5 units of energy are rejected into the house in the form of heat.
Thus 1 unit of electrical energy + 2.5 units of energy from the ground = 3.5 units of energy output delivered to the home in the form of heat.
The energy input to output ratio is termed the C.O.P. or Coefficient of performance. See Fig. 1. The higher the C.O.P is, the more efficient the Geothermal System is. A well designed Geothermal System using today's advanced geothermal equipment can generally deliver a seasonally averaged C.O.P. between 3.2 and 3.6.
So you can now see that it takes less energy to move heat from the ground into the home using a Geothermal System than it does to produce heat by using burning a fuel.
Fig. 2. Compares in ascending order, the amount of heat obtained from various heating systems for every $ 1.00 CDN spent on fuel. 82% efficient furnaces are the least efficient furnaces available for replacement in Ontario. Systems shown in the 65% efficiency range can no longer be purchased for residential use and are shown for comparison purposes only. There are many hundreds of thousands of 65% efficient or less furnaces still operating in homes throughout Ontario however.
Fig. 2.
is based upon the following per unit energy costs:
- Natural gas = 51.6 cents per cubic meter average
- Electricity = 8.822 cents per kWh. average
- Propane = 59.9 cents per litre average
- #2 Fuel Oil =58.9 cents per litre average
Fig. 2. Illustrates some interesting points and dispels several energy myths at the same time.
Energy Myths Dispelled
- Natural gas is the cheapest way to heat a home – not true
- Electric heat is the most expensive way to heat a home – not true
- High efficiency propane is almost the same as heating with natural gas – not true
- Air source heat pumps are not as good as high efficiency gas and air conditioning – not true
In addition to the energy relationships outlined in Fig. 2., consumers should be aware that all furnaces consume electricity. Electricity is necessary for the control system to work and to operate the blower motor or pump that forces the heat around the home – this cost seems to often get forgotten when speaking with heating contractors, or fuel suppliers but electricity is a significant unseen cost when heating a home with a fossil fuel fired appliance.
Contact your geothermal specialists
or Telephone 519-808-3987