Colton Deck

By: Colton Deck on November 9th, 2022

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What Is a Heat Pump and How Does It Work?

Heating | Air

Everyone is familiar with air conditioners, but heat pumps have shaken up the residential heating and cooling game to great effect. But what is a heat pump exactly? We’ve got you covered in case you’ve been seeing heat pumps around and aren’t quite sure how they differ from standard air conditioning. 

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Being a milder climate, we’ve installed plenty of heat pumps in the Los Angeles area, which is a region that is ideal for heat pumps. Because of this experience, we can tell you that heat pumps are growing in popularity and present a unique value to some homeowners. 

In this article, you’ll learn: 

  • What a heat pump is
  • Types of heat pumps
  • Main components of a heat pump
  • How a heat pump works
  • Where to use a heat pump

With this information, you’ll have a great foundation of understanding when it comes to all things heat pumps and be able to shop with ease. 

What Is a Heat Pump?

A heat pump is an alternative to traditional air conditioners and furnaces. Heat pumps differ from both of their traditional counterparts by providing heating and cooling in a single unit. 

While some heat pumps resemble outdoor air conditioner units, they carry out both heating and cooling functions to save homeowners more space. Along with saving on space, heat pumps can provide more efficiency, with brands like Mitsubishi making some models that outpace the efficiency of traditional air conditioners by quite a stretch. 


Types of Heat Pumps

There are several different types of heat pumps on the market, but some aren’t as practical for residential use as others. The various types of heat pumps include:

  • Air-source heat pumps
  • Geothermal heat pumps
  • Absorption heat pumps

Take a look at each one to start thinking of which one is right for your needs. 


1. Air-Source Heat Pumps

Air-source heat pumps use electricity and are the most favored heat pump type for residential use, thanks to their efficiency and convenience. These heat pumps transfer heat in the air from one place to another. 

To break things down a bit further, air-source heat pumps warm a home by extracting heat energy from the outside air and moving it indoors. On the cooling side, the cycle is reversed. Air-source heat pumps cool by removing heat from indoors and pumping it outside. 

An inherent downside to heat pumps is that they do not produce heat and instead rely on the heat from the outside to warm a home. This means that temperatures below freezing can pose a challenge to heat pumps since there is less heat to pull in, which leads to the heat pump working harder to carry out its job. 


2. Geothermal Heat Pumps

Widely acknowledged as the most efficient form of heat pump, geothermal options use ground-source heat for their processes. 

Geothermal heat pumps use a closed loop of pipes buried beneath the ground to transfer heat in and out of the home. Because the ground temperature stays somewhat consistent, the cost to operate a geothermal heat pump is lower than other options. 

On the downside, geothermal heat pumps cost more to install since they require some excavation. This is really a balancing act between upfront investment and long-term savings. 

You’ll also need more space to install a geothermal heat pump than an air-source version. This aspect makes installing a geothermal heat pump in a residential area a little more challenging. 


3. Absorption Heat Pumps

The name of this heat pump type is a bit misleading. An absorption heat pump is essentially a heat pump that uses another power source other than electricity to carry out its heating and cooling roles. 

Absorption heat pumps use thermal energy generated by solar, natural gas, or heated water. The most common source is natural gas, though. 

A major downside of absorption heat pumps is that they negate the potential benefits of using an electric air-source model. Eliminating gas from the equation removes combustion from the equation, meaning less chance of fire, explosion, and carbon monoxide poisoning. 


Main Components of a Heat Pump

There are several main components of a heat pump system. Let’s focus on the most common option, air-source heat pumps, to get a better understanding of how the process is carried out. 

Things get a little technical from here on out, but hang tight! Once you have these basics down, you’ll have a clear understanding of how a heat pump works to better gauge whether they are for you or not. 

Check out the following components to lay the groundwork for understanding how a heat pump works. 


Indoor Unit

Air-source heat pumps use indoor and outdoor units to carry out heating and cooling processes. The indoor unit is an air handler, which are units that are placed in separate rooms to cool an entire home. 

Each indoor unit contains a coil that acts as both a condenser for heating and an evaporator for cooling. Along with the multi-use coil, the indoor unit holds a fan to blow air over the coil. Without the fan blowing air over the coil, there would be no way to distribute the air throughout the room. 


Outdoor Unit

Looking at the outdoor unit, things seem relatively similar since it also includes a condenser and an evaporator. But the main difference here is the heat transfer that occurs with the help of a fan. Without the fan, there would be no heat transfer. 



Just like traditional air-conditioners, air-source heat pumps use refrigerant to carry out heat transfer. The refrigerant needs to get around the system somehow. The device that carries out this function is called the compressor. 

The compressor pressurizes the refrigerant and pushes it around the system. Without a compressor, the refrigerant wouldn’t be able to carry out its job of transferring heat within the loop. 


Expansion Valve

Like every other component listed, the expansion valve plays a crucial role in how heat pumps work. The expansion valve controls the flow of refrigerant to the indoor unit’s coil. 

Expansion valves reduce pressure and prevent refrigerant from getting into the compressor and causing malfunction. 


Reversing Valve

Now, the part that really sets an air-source heat pump apart from traditional air conditioners. The reversing valve is what allows a heat pump to reverse its functionality to heat and cool. 

The reversing valve switches the flow of the refrigerant, allowing for a seamless transition from heating to cooling and back again. 


How a Heat Pump Works

A heat pump uses a number of parts to carry out its function. So far, we’ve covered how each part works independently of the others, but we can streamline them all into one simple process. 

Heat pumps work by transferring heat from one place to another using a series of components that are powered by electricity, natural gas, solar, or heated water. Moving heat relies on either air transfer or ground and water heat transfer. 

The core process is pretty simple to grasp, but breaking it down into individual steps can get a little trickier. Stick with it, though!

Take a look at the process heat pumps used to cool a home. 

  1. Refrigerant enters the expansion valve as it enters the indoor evaporator coil. 
  2. A fan blows air from inside the house over the coil.
  3. Heat is transferred to the refrigerant inside of the coil during this process.
  4. Once the liquid refrigerant is heated, it transitions to a gas. 
  5. As a gas, the refrigerant moves through the compressor, where it is pressurized.
  6. After being pressurized, the refrigerant enters the outdoor coil. 
  7. The outdoor unit fan distributes air from outside over the condenser coil.
  8. The refrigerant’s heat is then transferred to the outside air.
  9. As the heat is transferred, the gaseous refrigerant reverts to a liquid state. 
  10. The still-warm liquid refrigerant is pushed through the expansion valve to dial back the pressure on the refrigerant, which cools it. 
  11. The cycle repeats

But what about the heating aspect? Well, if you’ve got the cooling side down, then there’s little to worry about on the heating end. 

To heat a home, the reversing valve flips the flow of the refrigerant. This time around, air from outside is blown over the evaporator coil, where the refrigerant picks up the heat from the air. 

From here, the refrigerant is cycled through the system until it hits the condenser coil, and heat is released by the air blown over it

It’s really just a matter of reversing the process in your head to nail down how heat pumps can heat and cool. 


Where to Use a Heat Pump

OK, so now you know how a heat pump works, but can you actually benefit from one? Well, the answer will greatly depend on regionality. 

If you live in a more mild climate like Southern California, then the answer is a resounding “yes.” But if you’re posted up somewhere where temperatures drop below freezing in the winter, the answer is a bit more complicated. 

Heat pumps rely on heat energy in the outside air to warm your home. As temperatures drop below freezing, heat pumps will have a hard time carrying out their jobs and may not supply adequate heat. In these conditions, heat pumps will have to work harder to fulfill their promise, which can also affect their efficiency and energy consumption. 

Take the time to consider where you live before mulling over investing in a heat pump. It’ll save you from a lot of disappointment and cold nights in the future. 


Now You Know How a Heat Pump Works

We covered what a heat pump is, its various iteration, its main components, how they work, and if they fit your home. Now, you have enough information to decide whether continuing to explore heat pumps is in your best interest or if you should look elsewhere for your heating and cooling needs. You can also keep up with HVAC technicians who service your heat pump if you already own one and communicate more effectively what you need. 

Monkey Wrench Plumbing, Heating & Air understands that not every home is the same. Some homes may not be fit for a heat pump, and that’s OK. There are plenty of other traditional solutions to heating and cooling. 

If you’re in the Los Angeles area and are looking for a consultation on which HVAC system is best for you, call us at (310) 853- 8690 or visit our HVAC services page to get connected with a technician who can assess your home’s needs. 

If you’re keen on exploring heat pumps, you should get a better idea of what brands are the best and figure out what are the pros and cons you’ll have to deal with if you choose to go that route.