Ground Source Heat Pumps

Whether you are constructing a new building or replacing an existing heating and cooling system, consider a ground source heat pump — one of the most energy efficient and environmentally friendly electric heating and cooling systems available.

Ground source heat pumps are not only environmentally friendly, they can also cut heating costs by around 50 – 70 per cent when compared to a regular electric heating system. The reason ground source heat pumps (sometimes known as a geothermal heat pump) are so efficient is because they move existing heat in or out of the ground instead of creating heat by burning fossil fuels or powering an electric element.

How does a ground source heat pump work?

An electric pump circulates a heat transfer fluid through a loop of pipes which are typically buried underground. In heating mode, the fluid in the loop absorbs heat from the earth, which stays at a stable temperature regardless of the temperature above ground. The heat in the fluid then passes through a heat exchanger into the heat pump where it is extracted and delivered to either a fan coil or a radiator system located in the building.  This process reserves when the system operates in cooling mode and heat from the building is rejected back into the ground.

The ability of the ground loop to transfer heat from the earth to the building is a key component in the effectiveness a ground source heat pump system. The length of the ground loop depends on the size of the space you are heating and the amount of heat you need. Longer loops can draw more heat from the ground, but need more space to be buried in. If space is limited, vertical boreholes can be drilled instead.

Which ground loop configurations best suits your building?

Ground source heat pump systems use four basic ground loop configurations to turn your property into a source of energy. Which design best suits your situation depends on:

  • Ground conditions
  • Availability and quality of groundwater
  • Size of property
  • Size of building you are trying to heat

Here are the basic loop configurations:

Vertical Closed Loops

Vertical closed loops are ideal where land is limited. It’s the most popular loop configuration for commercial applications.

Some technical details:

  • Ground temperatures are more constant at a depth of 20 feet or deeper, which means vertical loops require less piping than horizontal loops. 
  • In Manitoba, vertical loops are normally installed in boreholes measuring 50 to 300 feet deep and 10 to 20 feet apart.
  • A pair of pipes with a U-bend assembly is inserted into each borehole.

Horizontal Closed Loops

Horizontal closed loops are installed where soils can be easily excavated. They are generally not used for larger commercial applications and since they take up more land area, they’re typically used in rural areas where space permits.

Some technical details:

  • The pipe is buried in a trench, usually six to ten feet deep in one continuous loop or a series of parallel loops.
  • Horizontal loops are not recommended in dry sands and gravel.
  • They can work in moist clay and wet sand.
  • The deeper the loop is buried, the more heat there is to harvest.

Well-to-Well or Open Loops

Well-to-well or open loop systems extract heat directly from well water. Well water is pumped to the heat pump system from a supply well and is then returned to a second well or “return well”. All open loop systems are required to obtain a Water Rights Licence through Manitoba Water Stewardship.

Some technical details:

  • Typically, the entering water temperature of an open loop system is approximately 6˚C higher than a closed loop system, which can lead to improved system efficiency.
  • Water sources with high levels of salt, chlorides or other minerals are not recommended as they can cause premature system failure or inefficient operation. Regular cleaning and maintenance would be required.
  • Installations which require deep supply wells may require larger pumps which would increase the initial cost of the system.

Lake or Pond Closed Loops

Lake or pond closed loops are used if a pond or lake is nearby and the loop field can be submerged in water. Before installing this loop type, check with local authorities to ensure compliance with local laws and regulations.

Some technical details:

  • The loop field must be properly anchored to remain on the bottom of the body of water
  • It must be submerged deep enough underwater and must be protected at the shoreline to avoid being dragged.

Next Steps

Once you have decided to upgrade your heating system, we recommend getting several quotes from various contractors. Once you’ve selected an installer, make sure they obtain all the necessary approvals, water rights licenses, and permits.

To qualify for incentives from Efficiency Manitoba, your project must be pre-approved before work begins and the installation must be done by an accredited Manitoba Geothermal Energy Alliance (MGEA) installer. Since it is both costly and difficult to alter the loop once it has been installed, it’s crucial all of the equipment is properly sized to maximize system performance.