. . When heating or cooling your home, you want it to be comfortable. Making a home comfortable and affordable requires thought and planning. So, when buying a new heating and cooling unit, what is the best option? You hear a lot about heat pumps, that they are efficient and can save you money. This report will compare functionality and cost of ownership between two different heat pumps, the air-to-air heat pump and a geothermal heat pump. Air Source Heat Pumps (ASHP) Air to air or air source heat pumps use the outside air as its heat source whether it is heating or cooling an area. The heat pump will transfer heat energy from a cooler area to a warmer location. It operates similar to a standard air conditioning system, except in addition to cooling, it will also heat your home. The heat pump extracts heat from the air. It compresses the refrigerant to a high temperature and transfers the heat from one place to another. In the summer it takes the heat from your home and moves it outside. In the heating season, it takes the heat from outside and moves it inside to be distributed through an air handler. Air-to-air heat pumps are very effective in warm climates. In areas where it gets below 30⁰ F., an air source heat pump will require a back-up system. A suitable back-up could be electric heat or a fossil fueled system that uses natural gas, propane or oil. Below 30 ⁰ F, it costs more to extract heat from the colder air. You can run an air source heat pump below 30 ⁰ F, but will lose the cost efficiency gained from utilizing a heat pump. Efficiency is a key factor when selecting an air source heat pump. Efficiency is rated in two forms. One is Heating Seasonal Performance Factor (HSPF), which rates the efficiency of the compressor and the electric resistance elements. The most efficient air source heat pumps have an HSPF rating of 8-10. The second rating is Seasonal Energy Efficiency Ratio (SEER) Kelly Wilken Page | 1
used to rate the efficiency of the cooling system. The most efficient air source heat pumps will have a SEER rating between 14 and18. Heat pumps costs are relative to their efficiency, higher efficiency rated systems have a higher cost. Ground Source Heat Pumps (GSHP)
Ground source heat pumps or geothermal heat pumps run off electricity and transfer heat from the earth. This is accomplished by circulating a fluid through piping below the ground’s surface. These pipes are installed in long closed loops. This system works well because the ground's temperature does not change. At 6 feet below the earth's surface the temperature stays between 45⁰F and 75⁰F. Unlike the air-to-air heat pump, when using a ground source heat pump a backup system is not required, regardless of outside air temperature. With a ground source system, there is no outside unit. The main system resides inside the home and is not much larger than a standard furnace. The system contains only a compressor, heat exchanger and blower. The compressor is similar in size to a refrigerator or deep freeze compressor. The only equipment outside is the long underground piping loops. The length of these pipes could be a disadvantage if you do not have a lot of yard space. The piping can be installed horizontally or vertically, vertically being a more expensive option. Not having an outside unit means there is only one system to maintain. You also have the option to attach a hot water system to your GSHP, taking the place of a standard water heater. The biggest drawback to this type of system is the initial setup costs, with the biggest cost being the drilling or digging of the closed loop system. The biggest advantage of a ground source heat pump is the energy savings it provides. Ground source heat pump’s SEER ratings range from 15-25. Savings can increase even more
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when utilizing the system to heat your domestic water. Geothermal heat pumps are a very environmentally green option for heating and cooling a home. The advantages of geothermal energy are that once the initial investment is paid for, and energy is relatively free. And it's clean. There is little or no reliance on power from gas or electricity to provide heat, which is one of the main uses of energy in the home. The main need for electricity to run this system is for pumps to pump the water through the system. The advantages of geothermal energy are that it is cheap, once the ground works are done and incredibly green energy. There are no emissions from the provision of heat for the home and water (Marshall) Cost Analysis
For cost analysis comparisons, I used 3 tons of capacity for both the air source and geothermal heat pumps, using 2,000 hours of heating and 2,000 hours cooling. A common 80% efficiency system is used to show the overall savings by installing one of these energy saving options. An air source unit will cost around $1,800/ton of conditioning. The air source unit could cost somewhere around $500-$2,500 to install. A typical geothermal unit will cost around $2,500/ton of conditioning with installation costing $10,000-$30,000. With the large range of costs, I called a local HVAC company, Central Heating & Air, and got an installation quote for both systems. The quotes indicated a total install cost of $7,500 for the air source system and $18,000 for a geothermal system. Cost could be lowered depending on current local and federal government rebate programs After comparing total cost of ownership, after 8-9 years you would breakeven owning a geothermal system compared to an air source system. Both systems in the comparison are generally energy efficient systems. Upgrading from an older furnace and central air system to a geothermal system would generate greater savings. Over the long term, a geothermal system will be kinder to your bank account and our plant.