There is no doubt that geothermal systems are expensive. That is why it is especially important to maximize the energy efficiency in the building envelope – insulation and windows, prior to considering Geothermal.
Having said that there are numerous advantages to geothermal that a standard system cannot match.
What is Geothermal
A geothermal heat pump HVAC system and a standard heat pump HVAC system are essentially the same. You have the same ductwork, you have the same heat exchanging coil and fan inside, and the same compressor.
Where they differ is in the media that they utilize to exchange/store the excess heat or cold.
In a conventional heat pump system, the system relies on exchanging the temperature with the outside air, which varies widely depending on the season.
As the outside temperature gets hotter the unit gets less efficient, and as the temperature gets closer to freezing the unit for all practical purposes stops working completely, rather relying on electric heat strips to provide hot air, while the outside unit heats itself up to thaw several times an hour!
Water is always a better heat transfer media than air.
In a geothermal heat pump, the system works with the earth’s relatively stable temperature of around 68 degrees year round. In Austin this is accomplished with drilling 250-300 foot deep wells, usually one well per ton of HVAC capacity.
These wellheads need to be stand alone, not tied into water wells, foundation piers, or anything else. As over time they can require maintenance and need to be accessible.
The system runs a closed loop of water through these wellheads, storing the excess heat during the summer and then extracting that heat during the winter.
As with all things, pricing varies from individual system to system. A good rule of thumb is between $7,000-8,000 per ton for a new system including ductwork, etc.
A high efficiency heat pump can run around $4,000-5,000 per ton.
Until the end of 2016, there is a 30% federal tax credit (1-1 credit). Apparently the IRS recently revised this to state that ductwork and backup heating are not included in the credit.
There is a lot of discussion about geothermal systems failing do to heat saturation. A properly installed system should not fail due to the heat saturation of the ground around the wellheads. This is accomplished by simply spacing the wellheads further apart and drilling the wellheads deeper.
Over 1,000,000 geothermal (or ground-source) heat pumps are used in U.S. residential, commercial and government buildings. And each year, U.S. homeowners install approximately 50,000+ geothermal heat pumps. As with any system proper maintenance of the compressor and water pump is important to the longevity of the system.
If you have questions about geothermal systems
Contact James Mcgee, Stan’s Heating and Air 512-929-9393
or Tom Rundberg All-Year Heating and Cooling 512-836-2222
Beyond the cost and expected payback. There are some additional benefits that are hard to quantify.
- If your goal is to have a Net-Zero home, or you are considering Solar Energy, than you should consider geothermal. It is very hard to compete with the efficiency of the unit, especially with the current efforts by Utility companies to make Solar less attractive.
- A geothermal system can be tied into your hot water heater, essentially providing free hot water anytime the system is in cooling mode. In Austin from May-October.
- There are systems that have been in operation for over 30 years. Expected life span is 20+ years.
- There can be no outside unit. If you are tired of hearing your outside A/C compressor running day and night, the geothermal unit is considerably quieter. Although newer quality heat pumps are quite a bit quieter as well.