All about ground source heat pumps

Whether you’re 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 can reduce your heating costs by up to 60% when compared to an electric furnace. For the average home in Manitoba, that translates to annual savings of $900 on your energy bills! Plus, we offer incentives of up to $2.50 per square foot of heated space to help you with the cost of replacing your existing electric or natural heating system with a ground source heat pump.

The reason ground source heat pumps (sometimes known as geothermal heat pumps) are so efficient is because they move existing heat into or out of the ground, instead of creating heat by burning fossil fuels or powering an electric element.

HOW A GROUND SOURCE HEAT PUMP WORKS

An electric pump circulates a heat transfer fluid through a loop of pipes which are typically buried underground. In heating mode, the fluid inside the loop absorbs heat from the earth, which stays at a stable temperature regardless of the temperature above ground (yes, even in Manitoba winters!). The heated fluid then passes through a heat exchanger into the heat pump, where the heat is extracted and delivered to either a fan coil or a radiator system in the building. This process reverses when the system operates in cooling mode and heat from the building is redistributed back into the ground.

THE IMPORTANCE OF THE GROUND LOOP

The ability of the ground loop to transfer heat from the earth to the building is what makes ground source heat pump systems so effective. The length and depth of the ground loop depends on the size of the space you’re heating and the amount of heat you need. Longer loops can draw more heat from the ground but need more space in which to be buried. Deep vertical boreholes can be drilled for loops when space is limited or to take advantage of the warmer soil temperatures available at greater depths.

When comparing quotes, pay attention to the ground loop length, depth, and spacing. Loops with tight spacing will reduce long-term heating efficiency.

WHICH GROUND LOOP CONFIGURATION BEST SUITS YOUR BUILDING?

Ground source heat pump systems use four basic ground loop configurations to turn your property into a source of energy. The best design for your needs depends on ground conditions, availability and quality of groundwater, the size of your property, and the size of the building you’re heating.

VERTICAL CLOSED LOOPS

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

Technical details:

• Ground temperatures are more consistent 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 in areas where soils can be easily excavated. Because they take up more land area, they’re more common in rural areas.

Technical details:

• The pipe is buried in a long trench, usually six to 10 feet deep, in one continuous loop or a series of parallel loops.
• They can work in moist clay and/or wet sand.
• Horizontal loops aren’t recommended in dry sands and/or gravel.
• The deeper the loop is buried, the more heat there is to be harvested.

Well-to-Well or Open Loops

Well-to-well or open loop systems extract heat directly from well water. Well water is pumped from a supply well to the heat pump system and is then returned to a second well or “return well”. A Water Rights Licence must be obtained from Manitoba Water Stewardship to install this type of loop.

Technical details:

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

Lake or Pond Closed Loops

Lake or pond closed loops can be 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 your plans comply with local laws and regulations.

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 by the waves.

Next Steps

Before you upgrade your heating system, it’s a good idea to first improve the insulation, windows, and airtightness of your home or building. These measures are often more cost effective at lowering energy bills and could help lower the cost of your heat pump system by reducing the size of heating system that you need.

Once you’re ready to upgrade your heating system, we recommend getting quotes from several Manitoba Geothermal Energy Alliance (MGEA) accredited installers. Ask for references from past customers and look for reviews from sources such as the Better Business Bureau. Once you’ve selected an installer, make sure they obtain all the necessary approvals, water rights licenses (if applicable), and permits.

We also offer incentives for ground source heat pump installations! Participating in our Heat Pump Program has the added benefit of requiring installers to verify they sized and designed the heat pump using calculations specific to your building versus general estimates. Learn more about our Heat Pump Program and see if you qualify.