What is a heat pump?

Heat pumps are heating and cooling systems that are extremely energy efficient. Heat pumps have been around for decades but only over the last few years have they started to see very strong market growth. The rising energy costs are driving people to invest in long-term solutions for reducing heating costs.

Heat pumps don’t use fuels to produce heat but move heat from one place to another. They need a source of heat which can be the outdoor air, the ground or water. Since they extract heat from one space instead of creating it, they are the most energy efficient way to heat and cool a space.

How does a heat pump work? What are the components of a heat pump?

Heat pumps transfer heat from one place to another. As opposed to other heating systems that use fuels to generate heat, a heat pump moves heat energy from the source into your home. Heat pumps rely on a heat source such as the air, the ground or water bodies.

Air-source heat pumps extract heat energy from the air outside to the building’s interior, transferring heat using a refrigerant.  The heat pump absorbs heat using an evaporator. A compressor increases the temperature further before it uses refrigerant to move the heat. The heat is then transferred through a large heat exchange surface which heats the water in radiators or underfloor heating. Let’s look at this in more detail below.

What happens inside a heat pump?

It all starts at the evaporator. 

Heat is extracted from the outside air through the evaporator, which acts as a heat exchanger for the refrigerant.

When the refrigerant enters the evaporator, it is in the form of a low-pressure liquid. The refrigerant then evaporates as the outside air passes through the evaporator. This happens as the refrigerant absorbs heat from the surrounding environment. The heat stored in the refrigerant is called latent heat.

The refrigerant – now in a low-pressure gas state – enters the compressor next.

The compressor.

Here the refrigerant is compressed. The compression process turns the cool, low-pressure gas from the evaporator into a hot, high-pressure gas.

The condenser.

The refrigerant – now a hot high-pressure vapor – enters the condenser.

Here is where the heat will be transferred to the heat sink (which is whatever we want to heat). The condenser is essentially a heat exchanger between the refrigerant and our heat sink (water or air).

Typically, air or water is passed over metal coils that contain the hot refrigerant. That air or water absorbs the heat from the refrigerant which condenses into a high-pressure liquid as it loses heat.

This high-pressure warm liquid then passes on to the expansion valve.

The expansion valve.

The expansion valve depressurizes the refrigerant, which also drops its temperature further and prepares it for a new refrigeration cycle for the evaporator.

This process is known as the refrigeration cycle. Instead of using the air as a heat source, ground-source heat pumps extract heat from the ground and water-source heat pumps from bodies of water.

Reversible heat pumps, which can both heat and cool your home, essentially reverse the refrigeration cycle. This way the heat pump takes heat from the inside of the building and expels it into the air outside. This way the heat pump acts like an air conditioner.

Here’s an illustrated, clear explanation of how heat pumps operate and how the refrigeration cycle works. 

How is an air source heat pump different compared to an air conditioner?

Air conditioners use the same operating principles for heating as heat pumps. Air conditioners are mostly designed to remove heat from the air inside your home. While air-to-air heat pumps can also operate just like an air conditioner to cool air, they are primarily designed for heating a home. They have larger evaporators to absorb heat more efficiently and other optimizations for home heating. Air-to-water heat pumps also offer better distribution than air-to-air units through radiators, underfloor heating or fan coils. 

Both air source heat pumps and air conditioners are available in the market as ducted units or ductless mini-splits. Ducted units work as a central air management system with air ducts to bring heat or cool into indoor air. Ductless mini-splits have an outdoor unit and an indoor air handling unit, and are ideal for single room heating and / or cooling. 

Can heat pumps also cool? Do they provide air conditioning?

Yes, some heat pumps can also provide cooling. Not all heat pumps can, but reversible heat pump models can switch the refrigeration cycle backwards so that the heat pump extracts the heat from inside the home and expels it outside. Other than the heat pump itself being reversible, the system must also include fan coils or air handlers to return the cooled air back into the building.  

What are the different types of heat pumps? 

Heat pumps fall into three main categories. Air-source heat pumps which use the air outside as a source of heat, water-source heat pumps that use a body of water as a heat source and ground-source heat pumps that use the ground’s heat as a source. Ground-source and water-source are often referred to as geothermal heat pumps. 

Air source heat pumps can be split into air-to-air and air-to-water heat pumps. The first uses air as a means to heat or cool a space and the second uses radiators, underfloor heating or fan coils. 

Geothermal units are typically ground-to-water or water-to-water, but there are systems designed to use air as a means of heat distribution.

Hybrid heat pumps can combine two different sources of heat into one or more distribution systems. 

Finally, some commercial / industrial heat pumps are designed to capture heat from industrial processes and reuse it for heating or cooling applications.

What are some common types of heat pump applications?

The versatility of the heat pump is exceptional. Let’s take a look at a few common applications.

Heat pumps can be used for heating and often for cooling too. As a heat pump heats a room, it can expel cool air (the byproduct of the refrigeration cycle) outside the building. This cool air however can be instead distributed into a room that needs cooling such as a cellar or a server room. 

Similarly, a heat pump that is cooling a room in a building can expel heat outside or use it for another application. This could be to heat a drying room, a pool or domestic hot water. 

Heat pumps can also capture heat and recycle it. Heat from industrial applications such as pasteurization or steel processing can be recycled to heat the building. 

What are the benefits of heat pumps?

There are many benefits to owning a heat pump. Heat pumps are extremely energy efficient and provide substantial cost savings. They can be paired with solar PV and energy storage to provide self-sufficient, carbon-neutral heating.

Heat pumps are incredibly versatile. They can be used to either heat or cool your home, heat domestic hot water, cool cellars, heat pools, capture heat from industrial processes and more.

Heat pumps also offer excellent comfort levels and very long lifespans with very little maintenance. This results in a very low total cost of ownership. 

There are so many more benefits to heat pumps we had to write an entire post just about them.

What are the disadvantages of heat pumps?

Proper sizing and installation is paramount for a new heat pump to achieve optimum efficiency. A properly installed heat pump can provide exactly the right amount of heat needed without costing more to buy or run.

 Unfortunately in the trade we sometimes come across improperly sized heat pump systems with too little or too much capacity. So it is extremely important that the heat pump installation is sized, designed and carried out by real experts. Luckily, TermoPlus heat pumps come with our full support for sizing. design and even customization. No other manufacturer offers this to customers at this level.

Reliable heat pumps are not cheap to buy. They cost more than most other heating systems. They are also the highest performing investment someone can make in a heating system. No other heating system can beat the incredible savings a heat pump can provide. Financing is a good way to get over the purchase cost barrier, with more financing options becoming available over the last few years.

These are the only two true disadvantages of heat pumps, and are easy to overcome. We’ve busted many heat pump myths before about heat pump advantages and disadvantages  

What are the pros and cons of owning a heat pump?

Once a heat pump has been properly installed, there really are no real disadvantages to owning it. Maintenance is easy and inexpensive, heating bills are low, the heat pump will last for a long time and the comfort it offers is excellent. 

Check out these common misconceptions on the pros and cons of owning a heat pump. as well as these benefits of heat pumps.

How energy efficient are heat pumps?

Heat pumps are the most energy efficient heating systems by far. For every kW/h of energy they consume, air-to-water heat pumps can produce 4kW/h of heat or more.

With the same 1kW/h of electricity geothermal heat pumps can produce up to 6kW/h of heat, or even more if heat energy is captured from industrial heat-generating processes. 

Compared to the 0.8-0.9kW/h of heat produced by gas or oil boilers and furnaces or 1kW/h of electric resistance heating it is obvious that heat pumps are the clear winners.

I’m told heat pumps are a good investment. What savings could I have with a heat pump? 

Heat pumps have a higher upfront cost than most heating and cooling systems. However, combined with their very long life expectancy (20+ years for most reputable brands, 25+ for TermoPlus & Mitsubishi heat pumps) and their exceptional efficiency, most heat pumps are typically paid off by the 7th year of ownership. From that year onwards, until the end of the heat pump’s life, the only ownership costs are the much lower energy bills and yearly maintenance.

There are many factors that affect the savings you can achieve and your return on investment. The cost of the right heat pump system, the system’s exact efficiency based on your home, the energy costs currently (and in the future) as well as maintenance costs, potential financing costs and the savings offered by subsidies affect this.

To get a more specific estimate on the savings you can expect based on these parameters, get in touch with us for a free quote

Are heat pumps really environmentally friendly?

Electric heat pumps don’t use fossil fuels. They operate only using electricity and only a very small amount  compared to resistance heating.

They can be incredibly environmentally friendly if the energy they use to create heat is green. If your grid provider is 100% green powered, then they will not contribute greenhouse gas or have a carbon footprint. The same goes if you fully power them with solar panels and energy storage.

Otherwise, they use the same fuel makeup as the grid that powers them (just like electric vehicles do). Their great energy efficiency is another bonus though, as they consume far less electricity than other electric heating and cooling solutions.

Can heat pumps work in the cold? Do I need a cold-climate heat pump? 

Heat pumps are an excellent heating solution for your home if you live in a cold climate. Heat pumps are also exceptionally efficient in heating even in extremely cold weather. Cold climate heat pumps are also incredibly robust and have been adopted in many countries with very harsh weather for the economy they offer. Whether you need a cold-climate heat pump or not is something you should discuss with your heat pump installer. 

Can heat pumps work with radiators? Is underfloor heating worth it?

Absolutely, heat pumps can work with radiators.

If you already have radiators installed, you will probably need to install a heat pump suitable for high temperature heating. Otherwise, it is likely a standard heat pump won’t be able to heat your home efficiently with older radiators.

If you are looking to replace an older radiator system you can consider either underfloor heating or low temperature radiators. They both require less heat from the heat pump to achieve the same heating effect, so they are extremely efficient in heating. These are almost equal in thermal performance but differ in installation costs and placement. 

Which are the best air-source heat pumps?

If you’re trying to decide which heat pump is best for you, you should consider your personal needs as well as the opportunities and restrictions set by your installation site. 

As they say in the trade, the best heat pump is the one that is installed correctly. This refers to both the proper installation and the proper sizing of the system. This means your options must also meet the right sizing requirement of the building. 

Comfort, ease of installation, cost of ownership, longevity, ease of use – there are so many different criteria to take into account. 

If you are looking for the best heat pump in terms of durability, reliability and efficiency then your best bet is a Mitsubishi external heat pump unit combined with a TermoPlus internal unit. We only use Mitsubishi external units due to their renowned durability, their ability to heat efficiently even in the most extreme cold as well as the exceptional efficiency they provide.

Since the largest cost associated with heat pump ownership is the initial investment, the best way to lower your overall cost of ownership is to pick a brand that lasts longer than the others. Mitsubishi does this with their superior industry-leading compressors (the most expensive component to replace in any heat pump), long-life brushless fan motors, Japanese inverters, electronic expansion valves and exceptional defrost programs. 

How do I choose the right heat pump system?

Buying a heat pump without the input of a heat pump system designer is not advised as it can result in overpaying for the system, low system efficiency or technical problems down the road.

What makes a good heat pump investment is precise sizing and a good understanding of the homeowner’s needs. The heat pump must have the right capacity so as not to consume more energy to operate. This reduces the investment cost (no overpaying), reduces the cost of ownership (greater efficiency) and extends the heat pumps productive life as it is not overworked.

Once your heat pump installer has conducted a proper site analysis then you will know what capacity heat pump you need and what characteristics it has to have. A heat pump installer will look into your current and future needs and advise you on your options so that you can make an informed decision.  

To get a free consultation on your heat pump needs, get in touch with us for a free quote

How do I choose the right heat pump installer?

Ask people you know for any references to installers they were happy with. Are they focused on heat pumps? Have they got a long history installing heat pumps? Check the installer’s reviews online and any case studies similar to your specific project.

Shortlist a couple of installers in your area that check all the right boxes and ask them for a site visit and consultation. Ask them questions to get an idea of how they treat their customers – are they informative, educative and respectful?

Ask for quotes from 2-3 of the final installers along with a proposal for your site. Make sure that you research these proposals further and make a decision taking into account how realistic their proposal sounds.

What does the future of heat pumps look like?

Heat pumps are constantly improving in so many ways. They are becoming even more efficient, quieter, smaller and easier to install and operate. They can operate efficiently in even harsher conditions and in colder temperatures than ever before.

With their exceptional energy efficiency it is likely that they will eventually become the de facto heating solution globally for both homes and businesses. What may change is the energy source that powers them. Whether this is the grid using more renewable sources or homeowners switching over to solar, this is the most efficient way to heat and cool for decades to come.