You’ve likely heard of geothermal, or ground-source heat pumps. They’re among the most practical, efficient, and popular home heating and cooling options for Canadian homeowners today.
See If Geothermal Is Right for YouLet’s explore what a ground-source heat pump really is, how it functions step by step, what’s inside, and how it stacks up against the systems most Ontario homeowners already use.
A geothermal heat pump, also called a ground-source heat pump (GSHP), is a heating and cooling system that uses the stable temperature below the ground to keep your home comfortable year-round.
It works by circulating a heat-transfer fluid through underground pipes called a ground loop. In winter, this geothermal unit absorbs heat from the ground and moves it into your home. In summer, the process reverses, removing heat from your home and transferring it back into the ground for efficient cooling.
A geothermal heat pump doesn’t generate heat by burning fuel or using electric heating elements. Instead, it moves heat between your home and the ground. Using a refrigerant cycle and a small amount of electricity, it transfers heat indoors during winter and removes it from your home during summer.
As you already know, a ground source pump operates in two modes, namely heating and cooling. Here’s a simple look at how it works:
During winter, a geo heat pump pulls heat from the ground and moves it into your home. Here’s how the process works:
Stage #1
Ground loop absorbs heat from the earth
A mixture of water and antifreeze circulates through the underground ground loop. As it travels through the soil, it absorbs the earth’s natural heat and carries that energy back to the geothermal heat pump inside your home.
Stage #2
The refrigerant evaporates
Inside your indoor unit, warm ground fluid flows near the cold liquid refrigerant. The refrigerant quickly absorbs heat from the fluid, causing the refrigerant to boil and turn into a low-pressure gas, while the ground fluid loops back outside.
Stage #3
The compressor raises the temperatureThe refrigerant enters the compressor as a cool gas. The compressor increases its pressure, which also raises its temperature. This creates the hot refrigerant needed to heat your home efficiently.
Stage #4
Heat is released into your homeThe hot, pressurized refrigerant gas flows through an indoor heat exchanger. As your home’s air passes over it, it absorbs the heat, causing the refrigerant to condense back into a high-pressure liquid.
Stage #5
The expansion valve resets the cycle
The liquid refrigerant passes through an expansion valve, which rapidly lowers its pressure and temperature, turning it back into a cold liquid ready to absorb more heat from the earth.
In cooling mode, the system seamlessly reverses this process.
It pulls heat out of your living space and dumps it into the ground. Because underground temperatures remain consistently cool, the earth acts as a massive natural heat sink, providing highly efficient cooling even on the hottest days of the year.
A geothermal heat pump system consists of several core components that work together to deliver efficient heating and cooling. 
Component | What It’s For | Did You Know? |
| Ground Loop (horizontal/vertical) | Transfers heat between the ground and the heat pump by circulating a water-antifreeze mixture | An improperly sized loop will ruin the system’s efficiency, so choose a certified installer. |
| Ground Source Heat Pump (indoor unit) | Extracts, concentrates, and moves heat between the ground loop and your home’s distribution system | This unit lasts much longer than ordinary ACs because it is housed safely indoors, away from harsh weather |
| Ductwork | Distributes heated or cooled air throughout the house through the ductwork system | Leaky ducts can waste up to 30% of your geothermal energy |
| Communication Modules | Includes smart controls, thermostats, and zoning systems that manage system performance | Geo systems work best when keeping a steady temperature, so avoid drastic “temperature setbacks” |
| Accessories (flow center, pumps, valves) | Keeps the loop fluid moving through the system and helps maintain proper flow and pressure | Opt for variable-speed circulation pumps. They automatically adjust fluid flow, using less electricity |
| Desuperheater | Recovers excess heat from the geothermal system to heat domestic hot water | This unit gives you virtually free hot water all summer long by recycling the heat pulled out of your house |
| Storage System (buffer tank/desuperheater tank) | Stores heated water, improves system performance, and can provide a reserve supply of hot water | A buffer tank prevents “short-cycling”, which protects the compressor |
Ground source heat pump (GSHP) systems are usually categorized in two ways: by the method they use to provide heating and cooling indoors, and by how they transfer heat to and from the ground.
These classifications are independent. For instance, a closed-loop system might use water-to-air cooling, while an open-loop system could use water-to-water cooling.
To clarify the options, geothermal heat pump heating systems can be divided into two primary categories:
| Type | How It Works | Best Suited For |
| Water-to-air | Transfers heat from the ground loop into forced air, distributed through ductwork | Homes with existing forced-air ductwork |
| Water-to-water | Transfers heat from the ground loop into heated water for radiant floors or hydronic systems | New builds, homes with radiant floor heating |
| System Type | Best Suited For | Did You Know? |
| Horizontal Closed Loop | Large yards or rural properties with plenty of open acreage. | It requires long, shallow trenches and is the most affordable to install, but it temporarily disrupts your yard |
| Vertical Closed Loop | Suburban homes, tight lots, established landscaping | These pipes go straight down into boreholes up to 400 feet deep. They use 80% less yard space than horizontal loops |
| Pond/Lake Closed Loop | Waterfront homes with a deep, permanent body of water nearby | Water transfers heat faster than soil, so submerging the pipes eliminates the need for costly digging entirely |
| Open Loop | Properties that already have a high-volume, reliable water well. | This system draws in groundwater, removes its heat, and returns it clean |
No matter which system combination you select, it will serve you well for decades by transforming the ground beneath your feet into a clean, highly efficient energy source.
When evaluating a geothermal heat pump, you will constantly run into two metrics: COP (Coefficient of Performance) and EER (Energy Efficiency Ratio).
Here is the simple breakdown of what they mean and how to read them. 
COP measures the system’s efficiency while it is in heating mode. It is a simple ratio of energy delivered versus energy consumed.
EER measures the system’s efficiency in cooling mode (acting as a central air conditioner).
Both technologies transfer heat rather than produce it, but their main difference lies in their energy source. 
| Feature | Ground Source (Geothermal) | Air-Source Heat Pump |
| Where it gets heat | The earth (always a mild 7–10°C underground) | The outdoor air (changes with the weather) |
| When it hits -20°C | Deep ground temperatures remain stable regardless of the weather | The system must work harder and use more electricity |
| Heating COP | 3.0 to 5.0 (delivers up to 500% efficiency) | 1.5 to 2.5 (drops significantly in deep cold) |
| Cooling efficiency | Very high (ground acts as a heat sink) | Moderate (air temp rises in summer) |
| Upfront cost | Higher ($25,000 – $45,000+) | Lower ($8,000 – $18,000) |
| Installation | Requires backyard digging or drilling | Just an outdoor unit bolted outside your wall |
| How long it lasts | 20–25 years for the indoor unit and 50+ years for the loop | 15–20 years max (it sits out in harsh weather) |
| Maintenance | Very Low since everything important is safely indoors | Moderate since it needs clearing from snow and ice |
Note: An air-source heat pump is cheaper to install and is a good option for moderate climates. However, in Ontario and most of Canada, where you need heat the most when it’s cold outside, a ground source heat pump is more efficient.
While both systems are designed to keep your home warm, the key difference lies in how they create that warmth.
| Feature | Ground Source (Geothermal) | Natural Gas Furnace |
| How it heats | Moves existing heat from the ground indoors | Burns natural gas to create new heat |
| Heating efficiency | COP 3.0 to 5.0 (300% to 500% efficient) | AFUE 80% to 98% (maximum 98% efficient) |
| Cooling capability | Yes. Full central air conditioning is built right in | No. Requires a completely separate central AC unit |
| On-site emissions | Zero. It eats and cools without burning fuel | Produces CO₂ and NO₂ from combustion |
| Upfront cost | Higher ($25,000 – $45,000+) | Lower ($4,500 – $9,500 for the furnace unit alone) |
| Lifespan | 20–25 years for the indoor unit and 50+ years for the loop | 15–20 years before requiring replacement |
Note: A gas furnace initially costs less to install. However, geothermal systems can be up to 400% efficient since they transfer heat rather than burn fuel. For Ontario homeowners, this can reduce yearly heating and cooling costs by 40% to 70%. Typically, it takes 10 to 15 years to recover the investment in a geothermal system.
Professional heat pump installation ensures efficient heating and cooling for your home, improving comfort and energy savings year-round.
Discover how geothermal systems use the ground beneath your home to heat and cool more efficiently than any traditional system.
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