Embracing The Elements: The Heat Pump Outdoor Unit

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By Debarghya Roy


Are you looking for a way to heat and cool your indoor spaces while being energy-efficient? Heat pump outdoor units might be the answer. Heat pumps are usually used as an alternative to air conditioning and heating systems, such as central heating systems or geothermal systems. They use heat exchange methods to quickly increase the temperature of the room by absorbing heat outside and transferring it indoors with minimal electricity usage. With all their benefits, from lower costs to improved efficiency ratings compared to conventional cooling systems, a well-maintained heat pump can keep your home comfortable year round.

heat pump outdoor unit

Image of a heat pump 

Key Takeaways

  • Heat pump outdoor units transfer heat energy from one location to another for home cooling and heating, while also being more energy efficient than conventional systems.
  • Different components of a heat pump system such as compressors, condenser coils, expansion valves, and evaporator coils help in efficiently transferring the temperature from outside into your space.
  • Size is an essential factor when selecting the right heat pump unit depending on available indoor/outdoor climate conditions plus insulating up walls connected thereto thus ensuring optimal performance& efficiency ratings over longer periods afterwards due do so.
  • Professional installation of a properly sized unit accompanied by regular maintenance & inspection visits/schedules should guarantee all-round satisfaction outcome regarding its successful operation with lower bills at much reduced running costs compared to traditional electric-based air handlers around as we go about our day-to-day lives too much good seek out only whenever warranted hereon!”

How Do Heat Pump Indoor Units Work?

Heat pumps extract heat from the surrounding air, geothermal energy stored in the ground, or nearby sources of water or waste heat like from a factory and redistribute it to warm up rooms in homes.

They use a refrigerant as part of their system that circulates between an indoor fan coil unit and an outdoor compressor. The refrigerant absorbs outside temperatures and carries it indoors.

The three main types of hot pump systems are air-to-air-source, water sourced, and geothermal and all have components such as compressors which help lift the temperature back up before being moved indoors through evaporator coils; thermostats to control how warm/cool each room will be; condensers that cool off heated liquids ready for release outside; indoor air handlers which work along with other parts as a circulation system; aluminum fins to protect any exposed metal parts against rusting; and finally for connecting both sides together via insulated refrigerant lines.

Components Of A Heat Pump Outdoor Unit

  1. Compressor: This is the main component of a heat pump outdoor unit and is responsible for compressing refrigerant and circulating it through the system. Generally, there are two types of compressors in use today: reciprocating and scroll. The type used depends on the size of the compressor, the temperature requirements, and the energy efficiency levels required.
  2. Condenser Coil: This is a finned tube that helps to dissipate heat from the inside of your home to the outside when air-conditioning or cooling mode is selected. It also has an important role when operating in heating mode as it helps to transfer warm air from outside into your home.
  3. Expansion Valve: The expansion valve is part of the heat pump’s refrigerant cycle and controls how much liquid refrigerant flows through the system at any time during its operation. It’s responsible for maintaining optimal pressure within the coils so that efficient transfer of heat energy takes place when in cooling or heating mode is selected.
  4. Evaporator Coil: This finned coil transfers condensed liquid refrigerant from outside to inside as part of the refrigeration cycle when in cooling or heating mode is engaged. It’s suitable for absorbing heat energy from outside your house on hot days and releasing it inside on cold days, depending on which mode you have selected at any particular time.

Choosing The Right Size Of Heat Pump Outdoor Unit

Choosing the right size of heat pump outdoor unit for your home is a crucial step to ensure optimal comfort and energy savings. The capacity of the heat pump plays an important role in finding the most suitable model for your needs, so make sure you do not underestimate or overestimate its size.

Smaller units tend to be more efficient because they can efficiently handle multiple temperature extremes while larger units may cost more upfront but require less maintenance overall.

Homeowners should also consider their local climate conditions, as well as layouts that have low-ceilinged rooms, poor insulation levels, large glass areas facing south/west or adjacent living places with common walls when picking out their appropriate system size.

Considerations such as these will help maximize overall efficiency ratings and ultimately reduce running costs significantly. 

Meanwhile, it is worth mentioning some common mistakes homeowners make when choosing a heat pump unit such as forgetting to factor in humidity levels in mild climates; ignoring unbalanced airflow issues within heated spaces; selecting too small outdoor units; failing to match indoor & outdoor components appropriately based on operating temperatures outside the range (-20 degrees F – 122 degrees F); and purchasing standby heating equipment along with summertime cooling technologies without considering potential winter warming requirements first before installing them all together.

Installation Of Heat Pump Outdoor Unit

The outdoor unit of a heat pump must be properly installed in order to ensure it runs efficiently and effectively.

Where To Install It?

When it comes to installing a heat pump outdoor unit, location is key. The placement of your unit can affect the amount of airflow, as well as its energy efficiency and noise levels.

Firstly, make sure that there is adequate space around the outdoor unit so that warm air from inside your home isn’t being pulled back into it. This could lead to decreased efficiency.

There should also be clearance around any vents or ductwork connected with the heat pump system. To ensure proper installation and operation of a heat pump system, choose a location that has several feet (ideally six feet) away from other objects such as buildings or trees.

Deciding whether to mount the outdoor unit on a wall or place on ground level will require consideration of local environmental factors and conditions such as access for servicing when necessary, proximity to sidings if mounting on an external wall and drainage possibilities if placing at ground level due to possible condensation fixtures within humid regions.

Professional Installation Or DIY?

Professional installation of a heat pump offers many advantages over DIY. HVAC technicians with Red Seal credentials are trained in the proper installation and maintenance of air-source or geothermal heat pumps.

They will assess your property’s climate, factor in existing insulation levels and determine the right size unit for optimal efficiency. Choosing the right sized unit is important to ensure proper performance as too small or large a unit could result in increased electricity costs from inefficient, excessive running time.

Professional installers often also provide guidance on location placement for maximum efficiency such as avoiding cold spots or direct sun exposure that can affect heat gain/loss, put home safety first by using best practices, and most importantly, guaranteeing their work with warranties on both parts and labor.

On the other hand, if you have experience in basic tools and electrical systems along with access to technical instructions then you may be up to the task DIY installation presents.

Generally, though it is something we wouldn’t generally advise due to potential electric shock hazards inherent when working with high-voltage appliances.

Maintenance Of Heat Pump Outdoor Unit

Regular maintenance of an outdoor heat pump will help ensure the unit is running smoothly and efficiently for optimal performance.

Optimal Performance

Regular maintenance of heat pump outdoor units is essential to ensuring they run at their best performance possible and consistent throughout the year. It should be done by a professional once or twice every year in most climates, depending on if it’s being used during all four seasons.

This will help ensure that components like coils, fins, fans, air filters, refrigerant lines are clean and working properly while emerging problems can be detected before any further damage occurs.

Homeowners can also inspect airflow around the unit from time to time and make sure there are no obstructions such as leaves, grass clippings or other debris blocking its condenser located outside reducing efficiency.

Regularly cleaning drain pans attached to evaporator coils and checking thermostats for power is crucial for preventing water leakage within your home. While switching up air to water heating, reduces risk of cold spots due to high energy losses associated with flowing refrigerant from one side of the system into the other. 

Winter Protection

It’s important to protect your heat pump outdoor unit from the cold winter months. While some heat pumps are built to withstand winter conditions, protecting it from the elements helps ensure its optimal performance and avoids any damage that could occur due to extreme temperatures.

Regular maintenance is essential for proper protection of your heat pump during the winter season. This includes making sure all parts are clean and functioning correctly, checking seals between moving pieces, inspecting refrigerant lines for leaks, ensuring condenser coils are free of debris or dirt buildup, and replacing air filters as needed.

You can also add additional care in preparation for colder temperature by draining water out of pipes connected to it and applying insulation on them if necessary. It’s also helpful to make sure you remove falling leaves or other debris from around the unit throughout fall so they don’t clog components when snow begins sticking around.

In addition, adding an AC cover over top is a great way to keep consequential moisture away while providing extra insulation against icy winds that blow through during freezing nights.

Energy Efficiency Of Heat Pump Outdoor Units

Understanding and utilizing energy efficiency ratings can significantly reduce the operational costs associated with using a heat pump outdoor unit.

Understanding Energy Efficiency Ratings

Heat pump outdoor units are rated on their energy efficiency with two ratings: SEER2 and HSPF2. 

The Seasonal Energy Efficiency Ratio (SEER) is used to measure the heat pump system’s energy efficiency during cooling mode while Heating Seasonal Performance Factor (HSPF) rating is similar to SEER rating, but this one focuses on the heating mode of operation.

Calculations for both of these ratings involve dividing the total BTUs (British Thermal Unit, a measurement of heat/energy) produced in a season by the amount of electricity used by the heat pump over that same time period.

As expected, higher numbers indicate greater electrical efficiency for a specific type, size or brand name chosen by consumers, meaning less electricity is consumed than lower-rated models without sacrificing comfort levels.

Heat pumps are still considered one of the most efficient ways to cool and heat homes compared to houses kept comfortable using other methods since they move existing warm/cool air instead of generating it from scratch.

Lowering Energy Costs

One of the major benefits of a heat pump outdoor unit is the cost savings associated with energy efficiency. Heat pumps offer much higher efficiency ratings than traditional HVAC systems for both heating and cooling.

For example, an air-source heat pump offers approximately twice the efficiency when compared to an electric furnace in terms of heating output per dollar spent.

Additionally, they can provide large gains in summertime cooling by using long-term energy storage methods such as ground source heat pumps or hybrid air conditioners which run during off hours and use stored energy to cool during peak demand times.

Many homeowners report substantial reductions in their utility costs after installing a temperature-controlled system due to these advanced technologies. An added bonus comes from qualifying for rebates from local utilities that are eager to promote high-efficiency equipment upgrades among their residential customer base.

Regular maintenance like changing air filters often, cleaning outdoor coils regularly, ensuring adequate airflow around and through the equipment, and having ductwork inspected for leaks/blockage; each one contributes directly toward lowering utility bills over time while increasing comfort levels inside the home.

Common Issues With Heat Pump Outdoor Units

Common issues with heat pumps outdoors include freezing up, defrost cycle issues, air leaks, fan malfunctions and low refrigerant levels.

Freezing Up

Heat pump freezing up is not normal and it’s important to identify the source of the problem. Inadequate airflow across the outdoor unit, which can be caused by obstruction or debris on the vents, will cause the heat pump to freeze over.

This type of problem is especially common during cold seasons when outdoor temperatures have dropped below freezing as this decreases airflow further. Low refrigerant levels can also contribute to a heat pump freezing up. Dirty coils limit air flow over them resulting in lower temperatures than expected and helping in a buildup of frost.

In hot weather, if an outside unit froze, then it could indicate a refrigerant leak or an issue with the filter being blocked and stopping proper air flow into its indoor counterpart causing compressor problems followed by ice accumulation and freeze-up in either sided components.

Defrost Cycle Issues

During a heat pump’s defrost cycle, the fan cuts off and the inverted refrigerant flow reverses. This enables hot gas cooled by passing over the outdoor condenser coil to be released into an indoor evaporator coil where it melts pulled-in ice and snow on the unit’s coils that gave rise to its name, i.e., heat pumps.

Common issues seen with a heat pump outdoor unit include wiring problems or damage to parts like the condenser coil, which can lead to faulty relays, controls, and sensors causing excessive build up of ice on them.

The blame for damages is placed upon two things, the frequency of defrost cycles due to weather conditions like cooler temperatures or covered units blocking essential airflow. But most often homeowners think their equipment has malfunctioned when they hear their unit going through an unexpected defrost cycle.

To avoid this confusion at home and ultimately save energy bills from extra costs resulting from too much strain put on your appliance due to these extra running cycles, you first have identify what is causing them, uch as bad insulation in an attic space where ductwork runs unprotected or unreliable thermostat settings at a temperature setpoint too high for milder winter days.

Air Leaks

When untreated, air leaks can spell disaster for your home’s heat pump system. Air leakage in the outdoor unit of the heat pump prevents it from properly pulling outside air for heating and cooling activities, resulting in energy waste and tremendous strain on the system.

The most common cause of an air leak is a blockage that keeps air from entering or leaving the outdoor unit due to snow or debris buildup. A cracked or broken condensate pan can also create an opening through which inside warm air escapes, introducing cool external temperatures into the heated space.

It forces extra effort from your pump. Additionally, ice accumulation around the cooling coils caused by low refrigerant levels puts immense pressure on metal parts which eventually may erode leading to refrigerant loss and further weakening of your equipment.

Fan Malfunctions

Heat pump outdoor units have fans that help to circulate air through the system. When these fans aren’t operating correctly, they can lead to serious problems with the heat pump and cause low energy efficiency.

Malfunctioning wiring, loose terminals, or damaged circuits can cause a heat pump to fail to turn on. Defective outdoor fans can also cause little to no airflow, leading preventing proper circulation in the unit and causing it to freeze over in colder weather.

Debris blocking the fan is another common issue that needs immediate attention as it will prevent the efficient operation of the heat pump. Additionally, strange or loud noises coming from within an outdoor unit may indicate a problem with the compressor valves, motor out of balance or broken fan blades as well as low refrigerant charge are some of possible causes behind such noise issues too.

Low Refrigerant Levels

Low refrigerant levels can cause serious issues with a heat pump outdoor unit. A shortage of the appropriate amount of refrigerant in the system may result in reduced cooling and heating capacity and may make it harder for the heat pump to do its job properly.

Additionally, improper charge levels can also speed up wear and tear, making it more likely that parts of your system will break or fail within their expected lifespan.

Problems with low refrigerants tend to happen due to leaks in either the indoor or outdoor units. Issues such as poor installation quality, physical damage over time due to weather conditions etc., could all lead to a leak developing which reduces pressure inside the lines.

It is important for owners of heat pumps to keep an eye out for issues with their systems and take quick action if they think there might be signs that something isn’t working correctly.

Troubleshooting Tips For Heat Pump Outdoor Units

With proper maintenance and regular cleaning, heat pumps can be energy-efficient solutions for heating and cooling homes. 

Here are some troubleshooting tips to help maximize the performance of your heat pump outdoor unit:

  • Check both power switches on your indoor and outdoor units. If yours doesn’t have separate power switches, look for a switch or breaker in each location.
  • Ensure there is no debris such as leaves or snow blocking the compressor fins outside near the air handler.
  • Make sure it isn’t accidentally switched to A/C mode.
  • Check that it isn’t iced over due to improper drainage of condensate water from the overflow pipe at times when humidity levels are high. This will stop its heating capabilities completely.
  • Cleaning the air conditioner’s filter every 1-3 months will help keep dust and dirt from clogging up system components which can impact efficiency by allowing more allergens indoors whilst using energy inefficiently.
  • It helps if you inspect all-electric terminal connectors on panels (incl breakers) with methyl alcohol spray. Often things like spiders crawl inside these little compartments causing “connector creep” meaning low connections don’t give enough current to run motors in equipment.
  • Inspect temperatures climb slowly through the thermostat. Try reversing the supply and return lines. Check if reversing the lines makes a difference. If there is a difference, it indicates a need for a service technician.
  • Pay attention to static 6 bias and other measurements during installation.
  • Replace any defective thermostats as these could prevent them from starting when required (low voltage line issues).

Noise Reduction For Heat Pump Outdoor Unit

Nobody wants to put up with loud, disruptive noise in their home, and heat pump outdoor units can be a major source of sound pollution.

Fortunately, there are ways that homeowners can work towards reducing the noise coming from their heat pump’s outdoor unit while keeping energy efficiency intact.

While these are all design considerations meant to help lessen noise levels coming from heat pump outdoor units during installations, one thing potential buyers should consider even before buying their machine is researching which machines offer the most efficient installation profile achievable along with its acoustic dissipating components.


What is a heat pump outdoor unit?

A heat pump outdoor unit is an air-source external heating system used to warm or cool buildings by pumping heated or cooled air indoors. It works by drawing ambient air from the outdoors and then transferring the energy to either warm or cool the home, depending on what setting has been selected.

How effective are heat pumps in cold climates?

Heat pumps are highly efficient in keeping homes and other commercial spaces at comfortable temperatures even during very cold winter months due to their ability to extract energy from outside sources and transfer it indoors without having to generate their own warmth as the traditional furnace does. This makes them a great choice for homes situated in colder climates where maintaining indoor comfort can be more of a challenge than in warmer areas with milder weather year-round.

What maintenance needs do heat pump outdoor units require?

To ensure optimal performance over time, regular maintenance should be performed on any type of HVAC system. Heat pumps included cleaning condenser coils, checking electrical connections, replacing filters when necessary, inspecting refrigerant lines for potential leaks and testing compressor motor voltage. 

Does installing a new outdoor unit require professional help? 

Yes, while some DIY spirit might have you considering attempting this kind of project all alone. Professional knowledge & experience can make all difference between success & failure so whenever possible enlisting what experts already know about trade should become the first go-to solution instead taking matters into your own hands.


Heat pumps are an excellent option for homeowners who want an energy-efficient, cost-effective way to heat and cool their homes. For many years, they have been the go-to system in areas with milder climates or moderate weather. However, with advances in technology, air-source heat pumps can now be used in colder climates as well. Heat pump outdoor units will require professional installation as well as regular maintenance after initial setup and throughout its lifetime of use on order to ensure optimum performance and efficiency.

Additionally, taking advantage of energy efficiency ratings such as HSPF and SEER when looking at a purchase is highly recommended by experts to lower the costs associated with serviced heating needs.

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