Geothermal FAQ

The three main parts are the heat-pump unit, the liquid heat-exchange medium (open or closed loop), and the air-delivery system (ductwork). The unit’s main components are the compressor, heat exchanger, air coil, blower motor and electrical controls.

Most units are easy to install, particularly when they replace another forced-air system. They can be installed in areas unsuitable for fossil fuel furnaces because there is no combustion, thus no need to vent exhaust gases. Ductwork must be installed in homes that don’t have an existing air distribution system. The difficulty of installing ductwork will vary and should be assessed by a contractor.

In all probability, yes. Your installing contractor should be able to determine ductwork requirements and any minor modifications if needed.

Geothermal heat pumps don’t use large amounts of power so your existing service may be adequate. Generally, a 200-amp service will have enough capacity and smaller amp services may be large enough in some cases. Your electric utility or contractor can determine your service needs.

Split systems can easily be added to existing furnaces for those wishing to have a “dual fuel” heating system. Dual fuel systems use the heat pump as the main heating source and a fossil fuel furnace as a supplement in extremely cold weather if additional heat is needed.

Geothermal systems used in climates where temperatures drop below freezing are generally installed with an auxiliary back-up electric resistance heater. This component is mounted either inside the unit or in the supply duct just outside the unit. The auxiliary heater serves two purposes: To supply back-up heat during cold outdoor temperatures, and to provide emergency heat if the compressor fails. Your geothermal unit will generate the largest majority of your heating needs; the rest of the heat would be supplied by the auxiliary heater. Generally, sizing the unit in a northern climate to provide 100% of the heating does not make sense economically because the added initial cost of the larger unit and earth loop may not be recovered in energy savings over a reasonable period of time. Software is available to assist the dealer in determining the most appropriate size system considering initial cost and operating cost.

Properly designing and installing an earth loop requires extensive training. In order to obtain optimum system performance, the earth loop size, design and configuration need to be carefully considered. In addition, special pipe, fittings, and tools for heat fusion and system flushing are required.

The actual process of installing the loop will disrupt the surface to some degree. With proper restoration, most loop fields are “invisible” after a couple months. After the initial installation, the loop will have no adverse effect on grass, trees, or shrubs. Nor will roots from trees cause a problem with the pipe.

Closed loop systems should be installed using only high-density polyethylene pipe. This pipe does not rust, rot or corrode, and is inert to chemicals normally found in soil. Properly installed, these pipes will last for many decades. Actual life expectancy of the pipe is over 200 years. PVC pipe should never be used.

Pipe sections are joined by thermal fusion which involves heating the pipe and fitting, then connecting them to form a joint that’s stronger than the original pipe. This technique creates a secure connection to protect from leakage and contamination.

No. An earth loop will reach temperatures below freezing during extreme conditions and may freeze your septic system. Such usage is banned in many areas.

All or part of the installations may be subject to local ordinances, codes, covenants or licensing requirements. Check with local authorities to determine if any restrictions apply in your area.

No. They are pollution free. The heat pump merely removes or adds heat to the water. No pollutants are added. The only change in the water returned to the environment is a slight increase or decrease in temperature.

There are a number of ways to dispose of water after it has passed through the heat pump. The open discharge method is the easiest and least expensive. Open discharge simply involves releasing the water into a stream, river, lake, pond, ditch or drainage tile. Obviously, one of these alternatives must be readily available and have the capacity to accept the amount of water used by the heat pump before open discharge is feasible. A second means of water discharge is the return well. A return well is a second well that returns the water to the ground aquifer. A new return well should be installed by a qualified well driller. Likewise, a professional should test the capacity of an existing well before it is used as a return.

Poor water quality can cause serious problems in open loop systems. Your water should be tested for hardness, acidity and iron content before a heat pump is installed. Your contractor or equipment manufacturer cant ell you what quality of water is acceptable. Mineral deposits can build up inside the heat pump’s exchanger. Sometimes a periodic cleaning with a mild acid solution is all that’s needed to remove the build-up. Where well water does not meet the requirements for an open loop geothermal system, a closed loop would be used.

Adopted from the Geothermal Journal

Used by permission – Water Furnace International Inc.