PSREC GeoExchange Heating & Cooling Solutions
Plumas-Sierra Rural Electric Cooperative )PSREC) offers incentives to encourage members to install ground source heat pumps — the single-most energy-efficient heating and cooling system on the market today!
Introduction to GeoExchange
Whether you are building a new home or considering a new heating and cooling system for your existing residence or business, you may want to consider the economical and environmental advantages of GeoExchange technology.
What is GeoExchange?
100% of the energy entering Earth’s atmosphere comes from the sun. About 50% of that (heat) energy is absorbed and stored beneath the earth’s surface in our land and oceans. Earth acts as a thermal battery, maintaining a relatively constant temperature all year long. It does this by being in radiative balance between incoming short wave solar radiation and outgoing long wave infrared radiation.
GeoExchange takes advantage of this natural phenomenon to provide clean, renewable, energy efficient heating, cooling, and hot water for homes and businesses. They move rather than create heat.
- GeoExchange systems (GHPs) in our area deliver roughly 3 units of useable heat energy (Btu/h) for every unit of electric energy input.
- They rely on the earth’s stored heat rather than burning fuel or generating heat directly.
How GeoExchange Works
(See drawing for reference.)
GeoExchange systems use the steady temperature beneath the earth’s surface for heating and cooling. Ground temperatures remain relatively constant (45° to 50° F) below the frost line, and the ground loop absorbs heat from warm earth. Cold refrigerant flows through coils, absorbing heat from warmer water in the ground loop.
Inside the home, warmed air is distributed through the house via ductwork. Room air returns to air handler, and in heating mode, refrigerant gives up heat to circulating interior air. The heat pump uses a common refrigerant cycle to highly concentrate the thermal energy and circulate it through ducted air or hydronic means.
- Ground Loop System
A network of sealed pipes (or ground loops) are hidden under a lawn or other landscape. Loops can be installed horizontally or vertically. The available land area and its geological makeup will help determine the most economical choice for installation.The system circulates a nontoxic water/antifreeze mixture through a closed-loop high-density polyethylene pipe. This solution transfers thermal energy between underground formations and the heat pump.
- Cooling Mode
A reversing valve changes refrigerant direction in summer. Domestic hot water can be heated whenever the system runs; in summer, this benefit is free. Rejected summer heat recharges the ground, increasing early-season heating efficiency.
Benefits of GeoExchange: Comfort & Everyday Experience
GHPs deliver warm air — not hot air. They are designed to deliver three to four air changes per hour. With good construction and proper duct design, GHPs supply about a 15 to 20°F temperature rise in heating mode with every air change. If the set-temperature is 70°F, the average discharge temperature through a GeoExchange supply duct should be 90 to 95°F. Typical forced-air furnace systems can heat air up to 130°F, which may feel too hot or dry.
Additionally, GHPs provide efficient cooling during summer months. If you previously used air conditioning, your new GeoExchange system will be more efficient and more affordable to operate. If you do not need air conditioning, you can switch off your system during a mild summer to save money.
Why GeoExchange Outperforms Other Systems
There isn’t a single more efficient heating and cooling technology than GeoExchange. Air source heat pumps, air conditioners and refrigerators all operate similarly in that they use a refrigerant to help move rather than create heat. The GeoExchange ground source heat pump takes this technology to the next level by using the earth itself as a heat source and heat sink.
The GeoExchange system draws up to two-thirds or more of the energy needed to warm a home from the earth. Only one-third or less is purchased electricity. Additionally, GeoExchange provides both heating and cooling with one system; fuel-based systems require separate equipment for heating and air conditioning.
Additional advantages:
- No outdoor equipment to maintain or risk damage
- De-superheaters can supplement a conventional water heater for additional savings
- No combustion, smoke, or storage tanks needed
- Reduced dependence on the earth’s finite fossil fuels
- Eliminates trucking of wood, gas, oil or propane
- Significantly reduces greenhouse gas emissions
GeoExchange systems are the quickest path to reducing greenhouse gases while simultaneously lowering electrical demand on the grid. As the grid increases its renewable energy mix, GHPs become even more environmentally beneficial. When paired with solar or wind power, homeowners can reach true Zero Net Energy goals.
Comfort & Quiet Operation
- Increased comfort
- Quiet operation
Efficiency & Cost Savings
- Reduced operating costs
- Unbeatable energy savings
- Nearly “free” domestic hot water pre-heat
System Durability & Design Advantages
- 3 times the longevity of standard A/C by removal of outdoor condenser
Environmental Benefits
- Less fossil-based energy burned for residential heating, and less energy consumed for heating or cooling
- Reduced greenhouse gas emissions
- Rejected summer heat back to the ground (some of which may be retrieved in winter) prevents a “heat island” phenomenon, letting neighbors’ A/C work against cooler ambient air
Grid & Renewable Energy Advantages
- Less pressure on the nation’s electric grid and lower future infrastructure costs as more people adopt efficient technologies
- Ground source heating and cooling is the only mechanism that can make use of a contribution by other renewable electricity generation to the grid.
Incentives & Certifications
- Government incentives (current 30% federal tax credit if the system is installed between 2017 and 2019, then drops to 26 percent in 2020 and 22 percent through 2021.)
- Co-op incentives
- Energy Star Logo GeoExchange systems have earned ENERGY STAR® certification and endorsements by the U. S. Department of Energy and the Environmental Protection Agency.
As you learn more about GeoExchange, you will see that it provides more comfort, cost-savings, and is more environmentally conscious than any other system on the market today!
PSREC Member Incentives
More than 450 PSREC members have installed GeoExchange systems.
PSREC offers 2 incentive options:
- One-time, $600 per-ton rebate (up to 50% of total system + loop cost)
- 15-year interest-free, non-transferable loan, added to the monthly electric bill
Careful design is critical to minimize costs and maximize efficiency. Discuss system specifics early when building a new home or business.
For information on PSREC’s loop loan program, including loan costs and a list of accredited IGSHPA contractors in your area, view the document GeoExchange Exterior Loop Loan Program (PDF).
For questions or concerns, call PSREC today.
- Make sure your system is installed by professionals who are licensed in California with no Contractor State License Board sanctions, and accredited by, and follow procedures established by, the International Ground Source Heat Pump Association (IGSHPA).
- Ask contractor for references of GeoExchange systems they have previously installed. Visit or call these references to ask about their experience and obtain recommendations.
- Expect a site evaluation so your contractor can make the best recommendation. This should include checking ducts, insulation and other features for building heat loss, including heat loss calculations from Manual J Wright, or similar.
- Get a narrative description of the system design and mechanics, including a plot plan of borefield or horizontal loop trenching with pipe and depth information.
- Get written cost estimates from 2 or 3 contractors. Ask for a breakdown between equipment and labor and get clarification on any questions.
- Get a written contract (including all terms, costs and start-stop dates) and a copy of the warranty (on the system and the installation). Be sure to ask for an owner’s manual.
- Require an inspection/verification measurement of bores (after grouting) or trenches before covering.
Call Plumas-Sierra Rural Electric Cooperative if you have any other questions or concerns.
- Is a GeoExchange system right for me? Discuss your needs for heating and cooling your home, any variations in occupancy, and whether you should “zone” your system.
- Should I have the loops installed vertically or horizontally?
- What heating capacity (Btu per hour) does my home require and how is this determined?
- Will auxiliary heat be required for my home?
- What is the brand name and efficiency of the system?
- What type of duct system will be installed and what is the insulation value?
- How do you seal your ductwork and do you test to verify the seal?
- How many supply and return vents will be installed and what are their locations?
- Is my system a single or dual capacity unit?
- Is my blower (fan) motor standard or variable speed?
There are many air filtration options available; discuss these with your contractor. - Ask if your contractor has a maintenance plan and how much it will cost
- What type of warranty is provided with my system and what is covered?
- There are many options in thermostat control; discuss these with your contractor.
- What are the benefits of a de-superheater and should I install one?
Plumas-Sierra Rural Electric Cooperative hired Efficiency Services Group, LLC (ESG) to evaluate GeoExchange performance in 2009.
eQuest 2000 SqFt. Model Findings
- Vertical GeoExchange is the most efficient method of heating a residence.
- Nearly 3 times as efficient as a propane furnace.
- Twice as efficient as a baseboard electrical system.
Plumas, Lassen, Sierra and Washoe counties are ideal climates for GeoExchange technology, similar to the upper Midwest, Canada and Sweden.
A properly designed system can heat a well-insulated building in sub-zero weather where stored underground thermal energy averages 40°F or better.
Heat Transfer Principles
- Heat moves from warmer to cooler areas.
- Greater temperature differences increase heat-transfer rates.
Below the frost line (3 to 5 feet deep), ground temperatures in this region remain between 35 to 50°F, allowing ground source heat pumps to operate more efficiently than traditional systems.
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GeoExchange systems require minimal servicing each year and have an exceptionally long lifespan.
System Longevity
- Residential heat pumps have lasted 35 years or more with minor maintenance.
- Underground loop piping is guaranteed for 25 years and expected to last over 50.
Routine Maintenance
- Annual servicing by a specialist
- Monthly air filter changes
- Rinsable and reusable electrostatic filters reduce cost further