How Heat Pumps Work

The Basic Idea

A heat pump doesn't generate heat the way a furnace does. Instead, it moves heat from one place to another. In winter, it pulls heat from a water loop or outdoor air and moves it into your home. In summer, it reverses the process — pulling heat out of your home and sending it away. One system, two seasons.

Think of it like a refrigerator that can run in reverse. Your fridge pulls heat out of the food compartment and releases it through the coils on the back. A heat pump does the same thing, but for your entire living space — and it can switch direction depending on the season.

Two Types of Heat Pumps in Toronto

Water-Source Heat Pumps (Most Common in Condos)

If you live in a Toronto condo, your unit almost certainly uses a water-source heat pump. Instead of exchanging heat with outdoor air, your heat pump exchanges heat with water that circulates through your building's water loop — a network of pipes that runs through every unit.

This is why water-source heat pumps are so efficient in condos. The water in the loop stays at a relatively stable temperature year-round, typically between 60°F and 90°F (15°C–32°C). Your heat pump doesn't have to work as hard as an air-source system that's fighting against -20°C winter air or 35°C summer heat.

Air-Source Heat Pumps (Common in Houses)

Air-source heat pumps exchange heat with outdoor air. They're common in houses and low-rise buildings. Modern cold-climate air-source heat pumps can operate efficiently even in Canadian winters, though they work harder than water-source systems in extreme cold.

How the Cooling Mode Works

1. Warm air from your condo is pulled across the indoor coil (evaporator)
2. Refrigerant inside the coil absorbs the heat from the air, cooling it
3. The now-cool air is blown back into your rooms through ducts or vents
4. The heated refrigerant travels to the water coil (condenser) where it releases the heat into the building's water loop
5. The cooled refrigerant cycles back to absorb more heat

How the Heating Mode Works

1. A reversing valve flips the direction of refrigerant flow
2. Refrigerant now absorbs heat from the building's water loop
3. A compressor concentrates this heat, raising the refrigerant's temperature
4. The hot refrigerant passes through the indoor coil, warming the air blown into your rooms
5. The refrigerant cools down and cycles back to absorb more heat from the water loop

Key Components Inside Your Heat Pump

• Compressor — The heart of the system. Compresses refrigerant to raise its temperature. The most expensive component to replace.
• Reversing valve — Switches the system between heating and cooling modes.
• Expansion valve (TXV) — Controls refrigerant flow. A common repair item.
• Indoor coil (evaporator/condenser) — Exchanges heat with your room air.
• Water coil — Exchanges heat with the building's water loop.
• Fan motor — Blows air across the coils and into your rooms.
• Thermostat — Controls when and how the system operates.
• Capacitor — Helps start the compressor and fan motors. A very common failure point that's inexpensive to replace.

Why This Matters for You

Understanding these basics helps you in two important ways:

1. Better conversations with technicians. When you know what a TXV valve or capacitor is, you can better understand what's being fixed and why.
2. Protection against unnecessary replacements. If someone tells you the entire unit needs to be replaced, but the actual problem is a $150 capacitor, knowing the basics helps you ask the right questions — or seek a second opinion.

If you have questions about your specific heat pump system, contact us or call 647-622-4123. We're happy to explain what's happening with your system in plain language.