Frequently asked questions
What is the payback period on a geothermal heat pump system?
The payback period varies significantly, as geothermal systems are customized to individual homes. Factors that influence the payback period include:
- new home vs. retrofit (existing) home;
- cost of the geothermal heat pump system;
- size of home;
- energy efficiency of the home and the age/type of heating/cooling system the geothermal heat pump is replacing.
In addition, premium system options may be selected for comfort reasons (i.e. combination distribution systems, electronically commutated motors (ECM) fans motors, etc.) which increase the total cost of the geothermal relative to a conventional heating system.
A simple payback analysis can be calculated from estimates/data provided by a geothermal contractor. To calculate payback, you will need:
- Geothermal system capital cost (obtained from your geothermal contractor)
- Base system installed cost (e.g. electric or natural gas and air conditioning system)
- Annual energy savings as a result from switching to a geothermal system (obtained from your geothermal contractor)
Simple payback formula: Payback in years = (A − B) / C
My property is not very large. Can I install a geothermal heat pump?
- heating requirements of home;
- access for drilling equipment;
- adequate spacing for the loop field;
- drilling obstructions – water lines, sewer lines and overhead/underground cables;
- drilling conditions;
- depth of bedrock
How does a geothermal heat pump differ from an air-source unit?
Air-source heat pumps absorb heat from outdoor air in winter and release heat outdoors during summer. The extreme outside air temperatures in Manitoba limit the effectiveness of air-source units in the coldest months of the year. In contrast, geothermal heat pumps extract heat from the ground, and provide a stable source of heat in the winter months.
How is the efficiency of a geothermal heat pump measured?
Efficiency is measured by the seasonal coefficient of performance (SCOP). This is determined by dividing the energy output of the heat pump by the electrical energy needed to run the heat pump system over an entire heating season. The higher the SCOP, the more efficient the heat pump is. Seasonal COPs of 2.0 to 3.0 are typical for today’s geothermal heat pumps. This means that for every unit of electricity that is used to operate the heat pump, 2 to 3 units of heat are generated. The efficiency for a heat pump – 200 to 300 per cent – can be compared with a furnace’s COP:
- mid-efficient natural gas – 0.80 (80 per cent efficient)
- high-efficient natural gas – 0.92 (92 per cent efficient)
- electric furnace or baseboard – 1.0 (100 per cent efficient)
Can a geothermal heat pump system be used with hot water space/hydronic heating?
Yes. Geothermal heat pump manufacturers offer units that produce hot and chilled water, rather than hot and cold air. These units can be connected to hot water space heating (also known as hydronic heating) equipment. The limitation in the heating mode is temperature. Conventional hot water radiators and baseboard-type elements are designed to operate at temperatures of 71°C and above (older systems operate as high as 93°C). Geothermal heat pumps are limited to producing supply water temperatures of less than 54°C.
As a result, on a retrofit basis, a home with existing hot water radiators or baseboards would have to replace the entire heating system, making the economics less favourable.
The best scenario to adapt an existing hot water system to geothermal is if you are currently using radiant in-floor heating or low temperature (less than 49°C) hydronic heating. These systems can operate with the lower water temperature produced by a geothermal heat pump.
With current North American residential design practice, complete space cooling cannot be accomplished with an in-floor system since condensation would occur on the floors’ surface. As a result, this system generally must be coupled with an air distribution system (air handler with cooling coil and ductwork) to provide cooling.
Does polyethylene piping affect the environment?
The pipe used in geothermal heat pump systems is a high-density polyethylene plastic that has no environmental impact on the surrounding earth. To avoid accidentally cutting the loop, your contractor should supply you with a dimensioned site plan. Always remember to call or click before you dig.
Is landscaping required after the installation of the ground loop?
Yes. The amount needed depends on the type of loop system installed. Horizontal loop configurations require the most landscaping work, as a large area of the land surface is disturbed during the trenching process. The amount of landscaping for a vertical loop installation depends on the number of boreholes drilled.
How does a contractor determine how much ground loop is required?
The purpose of the ground loop is to allow the heat transfer fluid to extract enough heat from the ground for efficient operation of the heat pump. A ground loop is designed to ensure that the heat transfer fluid will achieve a minimum entering fluid temperature when it enters the heat pump unit. Soil type and loop configuration determine the amount of ground loop required to ensure there is enough heat transfer to achieve this minimum entering fluid temperature for the system.