How Does a Heat Pump Work?

Wondering how a heat pump works? Whether you have a wall-mounted or central unit, this energy-efficient system can heat and cool your home — but only if it’s properly installed and suited to your space.

Heating Mode

Air-to-air heat pumps consist of an indoor unit and an outdoor unit. They heat your home by transferring heat from the outside air using a refrigerant. The system relies on a compressor and a heat exchanger to circulate and amplify this heat indoors. It’s the compressor that produces most of your heat pump’s heat output. It also circulates the refrigerant in the refrigeration circuit.

Refrigerant is a liquid with several characteristics, including the ability to change state (vapor or liquid).

When the compressor is running (heat pump cycle), it compresses the refrigerant to around 180°F. This turns the refrigerant into a hot vapour. The refrigerant is then piped to your indoor coil (evaporator).

At this stage, the temperature of the refrigerant gas in your indoor coil is around (85°F to 100°F). This is because it has been cooled on its way into your home. Your evaporator then acts as a heat exchanger. In other words, the interior fan extracts heat from the refrigerant in your home to heat the ambient air.

This process of heating and cooling systems is made possible by the reversing valve. This is the main component of the wall-mounted heat pump. It enables the refrigeration system to reverse the cooling cycle that normally takes place inside your home.

How air conditioning works

There are several types of air-conditioning units. The same goes for heat pumps: wall-mounted, central, multi-zone or built-in.

However, they all work in the same way. All air-conditioning systems have a compressor, which compresses the refrigerant to change its form into vapor. This is known as “hot gas”.

The refrigerant vapour is then cooled by a device known as a “condenser”. The condenser extracts the heat from the gas and converts it into a liquid. All refrigerants have different boiling point temperatures.

Once transformed into a liquid, the refrigerant is routed through an “expansion valve”. The regulator is an electronic or mechanical valve whose function is to create a gas shock. We call this “gas flash”.

Imagine a can of hair spray: inside is liquid, but when you press the nozzle, it comes out as gas.

In fact, when liquid passes through an orifice the size of a hair, the liquid turns into gas. This is called evaporation.

This is the property of the refrigerant. When the gas is subjected to the pressure of the expansion valve, it evaporates, creating cold in the air-conditioning coil. It is then extracted by the fan, which cools the space you want to cool.

Finally, the refrigerant begins its cycle again, thanks to the suction of the compressor. Please note that if the system is leak-free, the refrigerant is good for life!

The important thing for an air-conditioning or refrigeration system is to have no leaks and to maintain a good refrigerant level. Otherwise, the compressor will heat up and you’ll have compressor overheating problems.

Today’s residential air conditioners are much more protected than they used to be. They are equipped with thermal sensors and electronic probes. This makes it possible to detect temperature problems related to the compressor and refrigerant.

However, it is very important to have air conditioning units installed and checked by certified professionals.

What is a Heat Pump?

An air-to-air heat pump is a device that can provide both heat and cooling, using outside air as its energy source.

Unlike traditional heating systems, which burn fossil fuels to produce heat, an air-to-air heat pump uses a heat transfer process to extract warm air from outside and transfer this heat inside an area of your home.

How does a heat pump’s refrigeration circuit work?

An air-to-air heat pump operates using a reverse refrigeration cycle. This cycle consists of four stages:

1. Compression: the compressor compresses the refrigerant to raise its temperature.
2. Condensation: the hot refrigerant circulates through a heat exchanger, where it releases heat to the outside air.
3. Expansion: the refrigerant expands through an expansion valve, allowing it to cool.
4. Evaporation: the cold refrigerant circulates through another heat exchanger inside your home, where it absorbs heat from the indoor air.

This heat transfer process is repeated in a loop to maintain a constant temperature inside your home.

Advantages of a heat pump

There are several advantages to using an air-to-air heat pump:

1. Energy efficiency: an air-to-air heat pump can provide up to three times more heat than it consumes in electricity, making it a highly energy-efficient option.
2. Flexibility: an air-to-air heat pump can provide both heating and cooling, which means you can use a single unit all year round to maintain a comfortable temperature in your home.
3. Durability: air-to-air heat pumps are designed for long life and low maintenance.
4. Low CO2 emissions: air-to-air heat pumps use outside air as their energy source, which means they produce no CO2 when in operation.

The limitations of heat pumps

There are many advantages to using an air-to-air heat pump to take advantage of the heat contained in the outside air. But there are also a few limitations to consider:

Extreme temperatures: Some heat pumps may struggle to operate efficiently when the outside temperature is very cold or very hot. This depends in part on their energy efficiency performance. An efficient heat pump can produce heat down to temperatures of -30°C, while some heat pumps will have difficulty producing heat at -10°C. An additional heating system, such as electric baseboard heaters, is then required.

Noise: Heat pumps can be quite noisy when running, which can be annoying if you have close neighbors or a bedroom. Regulations on decibels and permitted locations vary from one municipality to another. This is an important aspect to consider.

Breakdowns or malfunctions: Although today’s heat pumps are extremely reliable, no appliance is immune to breakdowns or malfunctions.

For example, a heat pump that runs non-stop may reveal a control problem. A poorly calibrated thermostat, faulty sensors or a refrigerant leak can force the unit to run continuously to compensate for a malfunction.

When faced with this situation, start by making sure the thermostat is correctly programmed, examine the condition of the filters and be alert to any noise or abnormal behavior on the part of the unit. If the problem persists after these initial checks, call in our certified technicians, who can repair all brands of heat pumps.