What is a heat pump and how does it work?


One very important point to understand when answering the question “how do heat pumps work?” is that heat pumps do not generate heat – they move heat from one place to another. A furnace creates heat that is distributed throughout a home, but a heat pump absorbs heat energy from the outside air (even in cold temperatures) and transfers it to the indoor air. When in cooling mode a heat pump and an air conditioner are functionally identical, absorbing heat from the indoor air and releasing it through the outdoor unit. Click here for more information about heat pumps vs air conditioners.

When considering which type of system is best for your home, several important factors should be considered, including the size of the home and the local climate. A local Carrier dealer has the expertise to properly evaluate your specific needs and help you make the right decision.


A typical air source heat pump system consists of two major components, an outdoor unit (which looks just like the outdoor unit of a split-system air conditioning system) and an indoor air handler unit. Both the indoor and outdoor unit contain various important sub-components.


The outdoor unit contains a coil and a fan. The coil operates as either a condenser (in cooling mode) or an evaporator (in heating mode). The fan blows outside air over the coil to facilitate the heat exchange.


Like the outdoor unit, the indoor unit, commonly referred to as the air handler unit, contains a coil and a fan. The coil acts as an evaporator (in cooling mode) or a condenser (in heating mode). The fan is responsible for moving air across the coil and throughout the ducts in the home.


The refrigerant is the substance that absorbs and rejects heat as it circulates throughout the heat pump system.


The compressor pressurizes the refrigerant and moves it throughout the system.


The part of the heat pump system that reverses the flow of refrigerant, allowing the system to operate in the opposite direction and switch between heating and cooling.


The expansion valve acts as a metering device, regulating the flow of the refrigerant as it passes through the system, allowing for a reduction of pressure and temperature of the refrigerant.


One of the most important things to understand about heat pump operation and the process of transferring heat is that heat energy naturally wants to move to areas with lower temperatures and less pressure. Heat pumps rely on this physical property, putting heat in contact with cooler, lower pressure environments so that the heat can naturally transfer. This is how a heat pump works.[how-a-heat-pump-works-in-cooling-mode]


Liquid refrigerant is pumped through an expansion device at the indoor coil, which is functioning as the evaporator. Air from inside the house is blown across the coils, where heat energy is absorbed by the refrigerant. The resulting cool air is blown throughout the home’s ducts. The process of absorbing the heat energy has caused the liquid refrigerant to heat up and evaporate into gas form.


The gaseous refrigerant now passes through a compressor, which pressurizes the gas. The process of pressurizing the gas causes it to heat up (a physical property of compressed gases). The hot, pressurized refrigerant moves through the system to the coil in the outdoor unit.


A fan in the outdoor unit moves outside air across the coils, which are serving as condenser coils in cooling mode. Because the air outside the home is cooler than the hot compressed gas refrigerant in the coil, heat is transferred from the refrigerant to the outside air. During this process, the refrigerant condenses back to a liquid state as it cools. The warm liquid refrigerant is pumped through the system to the expansion valve at the indoor units.


The expansion valve reduces the pressure of the warm liquid refrigerant, which cools it significantly. At this point, the refrigerant is in a cool, liquid state and ready to be pumped back to the evaporator coil in the indoor unit to begin the cycle again.


A Heat pump in heating mode operates just like cooling mode, except that the flow of refrigerant is reversed by the aptly named reversing valve. The flow reversal means that the heating source becomes the outside air (even when outdoor temperatures are low) and the heat energy is released inside the home. The outside coil now has the function of an evaporator, and the indoor coil now has the role of the condenser.

The physics of the process are the same. Heat energy is absorbed in the outdoor unit by cool liquid refrigerant, turning it into cold gas. Pressure is then applied to the cold gas, turning it to hot gas. The hot gas is cooled in the indoor unit by passing air, heating the air and condensing the the gas to warm liquid. The warm liquid is relieved of pressure as it enters the outdoor unit, turning it to cool liquid and renewing the cycle.


A heat pump is a versatile, efficient cooling and heating system. Thanks to a reversing valve, a heat pump can change the flow of refrigerant and either heat or cool a home. Air is blown over an evaporator coil, transferring heat energy from the air to the refrigerant. That heat energy is circulated in the refrigerant to a condenser coil, where it is released as a fan blows air across the coil. Through this process, heat is pumped from one place to another

7 signs you need a new air conditioner

1. You’re not getting cold air.

Maybe it’s obvious, but when you’re not getting any cool air, there’s probably something wrong with your AC. From low Freon levels to a broken compressor, any number of issues could be a factor. Call in a professional, or if you have a home warranty with Select, make a claim. There’s no need to wait to beat the heat. If the repair is extensive, you may be looking at a replacement instead.

2. The air flow isn’t all that great.

So maybe you’re getting cool air throughout your home, but you’ve noticed that your AC isn’t pushing air out the way it used to. This could mean any number of things, including issues with your AC’s compressor or blocked/damaged vents. While it’s possible to have a professional manage these repairs, they can be quite expensive depending on your system’s age and the extent of the issue. When the costs get too high, you might want to consider the cost for a new unit.

3. You’ve found moisture and leakage around the unit.

While condensation around an air conditioner is normal, excessive leakage can represent a much larger problem. If you have an issue with a refrigerant leak or notice large pools of water around your AC unit, you may have a serious issue that need to be addressed right away. Leaking coolant can pose a health risk to you and your family, and excessive water leakage can damage floors or furniture and may even lead to mold growth. Call in an expert ASAP!

4. You’re hearing unusual sounds you haven’t heard before.

Did you hear a loud grinding sound coming from your AC? How about rattling, banging, squealing, and other noises that just don’t seem right? Turn off your AC system and get an expert out to look at it as soon as you can. These noises often reflect a serious issue – such as a belt slipping out of place or broken motor bearings – that could lead to a costlier repair or need for replacement if not addressed immediately.

5. Some zones aren’t cooled (aka the thermostat isn’t working).

Occasionally, issues with your AC system aren’t about the main cooling unit, but your thermostat. A broken thermostat may prevent the system from effectively cooling any given area in your home or apartment. If the other rooms feel fine and the issue is contained to a single zone, it may be worth having a professional check your thermostats to see if they’re culprit. If so, you might be lucky enough to have to replace a thermostat or two instead of replacing the whole system.

6. You’ve had it for more than 10-15 years.

The average AC system lasts about 10 to 15 years. If your system is older than that, congratulations! You got a great return on your investment. However, with newer models focusing on energy efficiency, you may save money in the long run through an upgrade. When your older system breaks down, consider it an opportunity to upgrade to a modern setup.

7. Your AC system needs frequent repairs.

Eventually, if you find yourself paying to have the same system repaired repeatedly, it may be time to throw in the towel. Sooner or later, it’ll be more cost effective to simply replace it. After all, repairs not covered under a home warranty can be incredibly costly.

How would an IAQ system benefit me?

Particles and allergens include dust, pollen, pet dander, and hair. These are not only irritating to people and pets, but are also bad for your heating and cooling system.
The disposable air filter in your unit captures less than 5% of the particles in your home. That means the other 95% are free to build up in your air conditioning system and float in the air you breathe. As the particles collect on your blower, ductwork, and coils, your unit has to work harder. You are likely to pay more in utilities and repairs, and it might reduce the life of your unit.
Most of us are aware of the effect germs have on our lives. What many of us don’t realize is that our heating and cooling systems can add to the growth and spread of bacteria, viruses, and other biological substances. This can cause your unit to smells like mold and mildew, an issue known as “Dirty Sock Syndrome”.

A UV-C lamp is installed in the ductwork near the blower. 98% of biological components are killed the first time they pass the lamp. This is far more powerful than the UV-C lamps seen on TV that take dozens of passes to kill less germs.
Want to know the best part? Improving the quality of the air in your home saves you money in repairs, system replacements, and doctors’ visits. You can say goodbye to dust, dander, chemicals, viruses, and so much more with our IAQ system. For more information or to receive a quote, contact our HVAC professionals.

Peak Performance During the Summer Months

The air conditioning experts at ENERGY STAR recommend changing your air filter every three months at a minimum. Dirt and debris in your filter can obstruct air flow, increasing the workload of your cooling system. By replacing the filter regularly, you can reduce wear and tear on your air conditioner while allowing the free movement of air for improved indoor comfort.

Why is changing your air filter so important?

The U.S. Department of Energy recommends regular maintenance for your air conditioning system to increase its efficiency and improve its performance. Replacing your air filter is a key part of that maintenance process. Here are some of the most important benefits of timely AC filter replacement for your heating and cooling system.

Reduced Chance of Breakdowns

As air filters become older and deteriorate, they can release fibers and debris directly into the moving parts of your air conditioning system. This can lead to mechanical breakdowns that can reduce the comfort of your Virginia home. By making sure your air filters are in good condition and free of excessive dust and debris, you can avoid costly repairs for your heating and cooling system.

Improved Indoor Air Quality

The right AC filter can screen out pollutants, particulates and dust to ensure the quality of your indoor air. This can have a positive impact on the health of your entire family and can be especially important for older people, children and those with respiratory issues. By replacing your filters regularly, you can enjoy improved indoor air quality for every member of your family.