Air Source Heat Pumps

Diagram of an air source heat pump

How They Work

Air source heat pumps (ASHP) are electric appliances that provide heating by moving heat into a building and cooling by moving heat out of a building. Heat pumps do not create heat through burning fossil fuels or through electric resistance like conventional heating systems. 

Instead, they transfer heat from one place to another by using a refrigerant that absorbs heat from warmer air and moves the heat into space with colder air. This is similar to the way that a refrigerator or air conditioner works except that it can move heat in either direction to provide heating or cooling.

Because it takes far less energy to move heat than it does to create heat, ASHPs are much more efficient: ASHPs offer 200-400+% heating efficiency compared to 80-90% for fossil fuels and less than 100% for traditional electric resistance heat—and can exceed the efficiency of window and central air conditioners as well.

What Makes an ASHP a Good Fit For my Needs?

If you answer yes to one of these questions, you could be a good candidate for an ASHP.

  • Do you currently heat with oil, propane or electric resistance and want to reduce your heating bill?
  • Do you want greater control over your home's comfort?
  • Do you have an existing heating or AC system that is 15+ years old?
  • Do you want central AC but don’t have/don’t want to install ductwork?
  • Do you have persistent cold/hot spots or a recent addition to your building?
  • Is someone in your household sensitive to air pollutants or allergens?
  • Do you want to reduce your household's carbon footprint?

Types of Air Source Heat Pumps

There are two types of ASHP systems available through HeatSmart CNY: ductless and ducted heat pumps.

Ductless air source heat pumps can provide heating and air conditioning without the need for central ductwork. Each ductless system includes one outdoor unit connected to one (single-zone) or more (multi-zone) indoor wall, floor or ceiling air distribution units. Ductless ASHPs are often referred to as ductless mini-splits.

Ductless air source heat pumps are the most efficient air-source systems and can be installed as either a primary source of heating and cooling or to supplement existing systems. Some examples of these supplemental applications include:

  • Installing indoor units in the most frequently used larger rooms like family rooms or master bedrooms to displace heating or cooling from your existing system
  • Installing indoor units in new additions to the building as the sole/primary source of heating or cooling
  • Placing indoor units in hot or cold spots of your home that can’t seem to be fixed with better insulation

Ductless indoor units come with remote controls (or smartphone apps!) that give you control over each unit and allow you to use them for heating, cooling, dehumidification or as a ceiling fan. Because each indoor unit can be controlled individually (forming an independent heating/cooling "zone"), you can heat or cool different zones in your home to different temperatures depending on personal comfort preferences—or reduce your energy use even more by turning down the unit in zones that are not being used.

A ductless heat pump system: (left) outdoor unit mounted above snow, (top-right) standard wall-mounted indoor unit, (bottom-right) floor-mounted indoor unit
A ductless heat pump system: (left) outdoor unit mounted above snow, (top-right) standard wall-mounted indoor unit, (bottom-right) floor-mounted indoor unit

 

Ducted air source heat pumps have an outdoor unit that is connected to an air handler in a building's ductwork, which is used to heat or cool the building. Ducted (also known as “central” or “unitary”) ASHPs are not much different from central air conditioners, except that they provide heating and cooling in a single system. (they don't look very different either!). Ducted ASHPs can work with your home’s existing ductwork, though some modifications may be necessary to adapt it from being suited for a furnace or central AC to being suited for a heat pump.

Ducted air source heat pumps can also be installed in a “hybrid” or “dual-fuel” configuration, where the heat pump is connected with an existing or new furnace. When temperatures drop below a certain level, the furnace kicks in, and in the summer, the heat pump provides central air conditioning. This configuration automatically switches to the low-cost heating system based on outdoor air temperature and can be a great option for homeowners with existing ductwork that want to keep the existing furnace in place while saving on heating and cooling.

Frequently Asked Questions

What are the benefits of installing an ASHP?

Energy savings. If you currently heat with oil, propane, or electric resistance heat, you could save hundreds of dollars a year on your heating bill by installing an air source heat pump. No need to pay thousands of dollars to get a gas connection to your home: a cleaner and cheaper alternative is already available.

High-efficiency cooling, no ductwork required. ASHPs also provide cooling and dehumidification and are more efficient and much quieter than window air conditioners, since the noisy outdoor components are separate instead of attached to the window unit. Ductless ASHPs can allow you to reclaim your windows and avoid having to install ductwork to stay comfortable in our increasingly-warmer summers.

Improved home comfort and health. In addition to providing cooling, heat pumps filter and dehumidify air, which can improve the air quality and comfort of your home. In particular, the filtration provided by ductless systems can significantly reduce allergens in your home for sensitive individuals. Central heat pump air handlers also have room for a variety of optional air quality improving devices, including electrostatic filters, UV filters, humidifiers, and heat recovery ventilators.

Flexible options. Heat pumps are a flexible technology that can be installed in homes of all shapes and sizes with different needs—whether you need a whole-home system replacement, have (or don’t have) ductwork, want to add zoning to your home, want to increase the efficiency of heating part of your home, or want to add extra heating/cooling to that part of your home which is never as comfortable as it should be.

Lower your carbon footprint. As a clean heating and cooling technology, converting from burning fossil fuels to using an air source heat pump will help reduce your carbon footprint and dependence on imported fossil fuels. Using solar photovoltaic (PV) panels or other renewable electricity sources can further offset emissions from the electricity powering your heat pump.


Do ASHPs work in New York winters?

The newest, cutting edge cold-climate ASHP models supported through HeatSmart CNY and rebated through state programs are optimized for New York’s year-round weather conditions. These models are certified based on their performance at 5° F, and are capable of continuing to provide heat even when the air temperature is as low as -13° F. While most central New York homeowners may want to keep an existing system in place for backup on the coldest days of the year, cold climate ASHPs are well-suited for providing year-round efficient heating and cooling.

Read Northeast Energy Efficiency Partnership's "Getting the most out of your heat pump" [PDF] for best practices.


What are some drawbacks of ASHPs?

Higher upfront costs. ASHPs cost more upfront than fossil fuel or central AC systems (but usually less than the two combined!). However, their higher efficiency will typically pay back the difference against oil, propane, or electric resistance over the course of several years.

Aesthetic considerations (ductless). ASHPs are typically installed indoors as a wall mounted unit (shown above). If you're concerned about aesthetics, discuss other installation options like ground-mounted or ceiling-recessed units with one of our installers.

Reduced performance in extreme cold. The heating output and efficiency of ASHPs declines as outdoor air temperature declines. Consider keeping your existing heating system in place as a backup system to utilize on the coldest days of the year, as heating with a heat pump on those days can be more costly than using the backup system.

Defrosting. Frost can form on the outdoor unit during periods of high humidity and near-freezing temperatures, obstructing airflow. When this occurs, the outdoor unit initiates a defrost cycle, which temporarily uses additional energy and reduces heating output.

Lower efficiency than Ground Source Heat Pumps (GSHP). Since the outdoor air's temperature changes more than the ground, ASHPs are typically less efficient than geothermal heat pumps. However, ASHPs are less expensive, quicker, and less disruptive to install.


How much maintenance do ASHPs require? ASHPs don't require much maintenance beyond cleaning air filters and keeping the outdoor unit clear free of snow, ice, and other obstructions. Annual or bi-annual servicing can ensure your system is well-maintained and keeps running at high efficiency.
How can I maximize my energy savings with an ASHP?

“Set it and forget it.” While many of us are used to turning off the lights and turning down the heat at night, heat pumps are most efficient when running continuously at partial output without sudden increases in heating demand from constantly adjusting the thermostat.

Think about it like how your car’s mileage improves when you drive at a constant speed instead of constantly stopping and starting. Consider only setting back your heat pump system when you’re gone for several days. Heat pump systems can be wirelessly controlled, so when you're on your way home you can adjust the thermostat from your smartphone and bring your home back up to the perfect temperature when you arrive.

Know when to use your backup system. Depending on the weather and the cost of your backup heating fuel, it may be more efficient to use your backup system during the colder parts of the year when heat pumps are at their least efficient. If you expect the temperature to be in the single digits or lower for the day, consider just turning your heat pump system off and firing up your backup boiler or furnace. If you have a dual-fuel system, this switch to your backup system will be done automatically.

Improve the efficiency of your home. A heat pump in a well-insulated home will perform better than in a poorly insulated home. Consider getting insulation, air sealing, and other upgrades (e.g. duct sealing) prior to installing your heat pump. Not only will your home be even more comfortable and your system perform better, but you may need a smaller (and cheaper) system to meet your home’s needs.


Why should I consider a dual-fuel system?

A centrally ducted heat pump can be tied into an existing or new furnace. When the outdoor air temperature reaches a particular balance point, it will automatically switch over to using the furnace, enabling you to use the lower-cost heating fuel at all times throughout the year. This balance point will differ depending on your the backup furnace and its heating fuel. Speak with your installer for more information on how to configure the balance point.

Dual-fuel systems can be great options for homeowners with suitable furnaces or who are concerned about a central ASHP being able to meet their heating needs year-round. ASHPs can only be paired with furnaces if they are designated as an air conditioning heating and refrigeration institute (AHRI)-matched pair. Speak with your installer to learn more about whether this is an option.

Dual-fuel systems can work for all heating fuels and can even offer an option for homeowners with gas furnaces. If you're considering adding central AC or need to replace your central AC, upgrade to a heat pump instead and you'll be able to heat at lower cost with lower carbon emissions during the shoulder seasons—and have central AC.

(Controls are available for some ductless ASHPs that can also trigger when your backup system kicks in. Speak with your installer to learn more about what options are available.)


How much could I save with an ASHP?

Under average energy prices from the last 5 years in the Central New York region, an ASHP could provide up to 60% savings for homes heated with electric resistance or propane and up to 30% savings for homes heated with oil. Homes that heat with gas would not be likely to see any significant energy savings due to the relatively low current cost of gas.

While every home is different and has different energy needs, typical costs to provide the same amount of heat by fuel/system type (measured in millions of Btus) are provided in the image below.

heat pump estimated operating costs

 

Your actual annual energy savings will vary based on a number of factors, including but not limited to:

  • How much energy prices change in the future. Energy prices—particularly fossil fuel prices—fluctuate from year to year. Your savings over the lifetime of the system will depend on how future costs of electricity change relative to the costs of the fuel you currently heat with.
  • How you use your system. As ASHPs are least efficient during the coldest parts of the year, how much you use your backup fossil fuel system will affect the overall efficiency of the system. Additionally, if you frequently set your system back, your system will have to work harder (and less efficiently) to bring the temperature back up.
  • How leaky your home envelope is. A poorly insulated home will need more heat to keep you comfortable year round. Using an ASHP in a leaky home will force your ASHP to work harder when it's coldest outside, increasing costs.
  • How well you maintain your system. A poorly maintained system will lose efficiency over time. Keep your filters clean to ensure your ASHP continues operating at high efficiency.

What incentives are available to me?

NYSERDA offers a $1000/ton rebate for a "whole home system" that covers 90%-120% of your heating load for cold climate ASHPs. The value of this rebate will be automatically removed from the cost of your system from any HeatSmart CNY installer.

National Grid offers rebates ranging from $200-375 per ton (12,000 Btu/hr of capacity) for cold climate ASHPs, depending on type and efficiency, for electric-only National Grid customers.

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