When most people think about heat pumps, they picture the standard unit mounted on the side of a house, pulling heat from the outdoor air. But air isn’t the only medium a heat pump can work with. A water source heat pump uses water – rather than air – as its heat exchange medium, and in the right setting, it’s one of the most efficient heating and cooling systems available. This guide covers how water source heat pumps work, how they compare to air source systems, and what to consider before choosing one. If you’d like to explore your heat pump options in more detail, Foster’s heat pump services are a good place to start.
What Is a Water Source Heat Pump?
A water source heat pump is a system that transfers heat to or from a water source rather than the outdoor air. That water source could be a lake, river, well, or a closed loop of fluid buried underground. Because water holds and transfers heat more effectively than air, these systems can operate at very high efficiency levels – even in colder conditions where an air source heat pump would have to work harder.
Water source heat pumps are used in both residential and commercial settings, and they’ve gained attention in recent years as homeowners look for efficient, lower-emission alternatives to conventional heating and cooling systems.
How a Water Source Heat Pump Works
The operating principle is the same as any heat pump: move heat from one place to another rather than generate it directly. In heating mode, the system extracts heat from the water source and transfers it into the home. In cooling mode, it works in reverse – removing heat from the indoor air and rejecting it into the water.
Because water temperatures remain relatively stable year-round – especially in underground sources – the system doesn’t experience the same efficiency swings that air source heat pumps can face during extreme cold or heat. That thermal stability is one of the core advantages of a water source system.
According to Natural Resources Canada, ground and water source heat pumps are among the most efficient heating and cooling technologies available for Canadian homes, capable of delivering three to five units of heat energy for every unit of electricity consumed.
Types of Water Source Heat Pumps
Water source heat pumps aren’t a single system – there are several configurations depending on the available water source and site conditions.
Open-Loop Systems
An open-loop system draws water directly from a well, lake, or other surface water source, runs it through the heat pump to extract or reject heat, and then returns it to the source or discharges it elsewhere. These systems can be highly efficient but require adequate water availability, good water quality, and compliance with local environmental regulations around water use and discharge.
Closed-Loop Ground Source Systems
Often referred to as geothermal systems, closed-loop ground source heat pumps circulate a fluid – typically a water and antifreeze mixture – through a series of pipes buried in the ground. The fluid absorbs heat from the earth, carries it to the heat pump, and the cycle continues. Because ground temperatures below the frost line stay relatively constant year-round, these systems deliver very stable performance regardless of outdoor conditions.
Closed-loop systems can be installed horizontally in trenches, vertically in boreholes, or in a pond or lake if one is available on the property. Vertical installations require less land but involve deeper drilling, which affects installation cost.
Surface Water Systems
Where a suitable body of water is nearby – a pond, lake, or river – a closed-loop system can be submerged directly in the water rather than buried in the ground. Surface water systems are often less expensive to install than ground loops because drilling or extensive trenching isn’t required. Water temperatures in surface sources can fluctuate more than ground temperatures, but they generally remain stable enough to support efficient operation.
Water Source vs Air Source Heat Pumps
Both system types move heat efficiently, but they suit different situations. Here’s how they compare on the factors that matter most.
Efficiency. Water source systems generally operate at higher efficiency levels than air source systems, particularly in colder conditions. Because water temperatures are more stable than air temperatures, the system doesn’t have to work as hard to extract heat in winter.
Installation cost. This is where air source systems have a clear advantage. Installing a water source or ground source system involves significant site work – drilling, trenching, or underwater installation – which makes upfront costs considerably higher than a standard air source heat pump installation.
Site requirements. A water source system needs access to a suitable water source or enough land for a ground loop. Not every property can accommodate one. Air source heat pumps, by contrast, can be installed almost anywhere.
Long-term operating costs. Because of their higher efficiency, water source systems typically deliver greater long-term energy savings. For the right property and situation, the higher upfront investment can pay off over the life of the system.
Maintenance. Both system types benefit from regular professional servicing. Closed-loop ground source systems have fewer exposed components than air source units, which can reduce some maintenance demands – but the indoor components still require annual attention. Foster’s HVAC maintenance services cover heat pump systems of all types.
Key Considerations Before Installing a Water Source Heat Pump
A water source heat pump isn’t the right fit for every home or property. Before moving forward, there are several practical questions worth working through.
What water source is available? Whether you have access to a well, a nearby body of water, or sufficient land for a ground loop will largely determine which system configuration is feasible for your property.
What are the local regulations? Open-loop systems that draw from and discharge to natural water sources are subject to environmental regulations that vary by region. A qualified installer will know what permits and approvals are required in your area.
What is the upfront budget? Ground source and water source systems carry significantly higher installation costs than air source heat pumps. BC rebate programs may apply to some configurations, which can help offset the investment – but it’s important to understand the full cost picture before committing.
What is the long-term plan? Because of the higher installation cost, water source heat pumps make the most financial sense for homeowners who plan to stay in their home long enough to realise the energy savings over time.
A licensed HVAC technician with experience in water source systems can assess your property and give you a clear picture of what’s feasible and what the numbers look like.
Is a Water Source Heat Pump Worth It?
For the right property and situation, absolutely. The efficiency advantages are real, and for homeowners with access to a suitable water source or adequate land, a water source heat pump can deliver exceptional long-term performance and meaningful energy savings.
For most urban or suburban homes without access to a well or suitable land, an air source heat pump remains the more practical and accessible option – and modern air source systems are highly efficient in their own right.
The best way to know which system suits your home is to have a qualified technician assess your specific situation. Foster Heating & Cooling has been helping homeowners find the right heating and cooling solutions since 1928, and we’re happy to walk you through the options. Get in touch with our team today.
Frequently Asked Questions
What is a water source heat pump?
A water source heat pump is a heating and cooling system that transfers heat to or from a water source – such as a well, lake, river, or buried ground loop – rather than the outdoor air. Because water holds heat more effectively than air, these systems can operate at very high efficiency levels.
How efficient is a water source heat pump compared to an air source heat pump?
Water source systems are generally more efficient, particularly in colder conditions. Ground and water source heat pumps can deliver three to five units of heat for every unit of electricity consumed. Air source systems are also highly efficient, but their performance can vary more with outdoor temperature changes.
What types of water source heat pump systems are there?
The main types are open-loop systems that draw directly from a water source, closed-loop ground source systems with buried pipe loops, and surface water systems with loops submerged in a pond or lake. The right type depends on your property and what water sources are available.
Are water source heat pumps more expensive to install?
Yes – significantly more than air source systems, due to the site work involved in drilling, trenching, or underwater installation. However, higher efficiency means lower long-term operating costs, and some configurations may qualify for BC rebate programs.
Do water source heat pumps work in BC’s climate?
Yes. Ground and water source systems are well-suited to BC’s climate. Ground temperatures below the frost line remain stable year-round, which supports consistent, efficient performance regardless of what’s happening above ground.
Can a water source heat pump provide both heating and cooling?
Yes. Like air source heat pumps, water source systems operate in both directions – heating in winter and cooling in summer – from a single unit.
How long does a water source heat pump last?
With regular maintenance, water source heat pump systems can last 20 to 25 years or more. The ground loop components in closed-loop systems are often rated for 50 years or longer.
