Frequently Asked Questions
Get your questions answered about heat pumps, HeatSmart, and the incentives available to you!
- What are the benefits of using an air source heat pump?
- Don’t air-source heat pumps perform poorly in cold climates?
- Are there other drawbacks to air source heat pumps?
- Is an air source heat pump right for me?
- Why are air source heat pumps considered “clean heating and cooling” technologies?
- How efficient are air source heat pumps?
- How do the annual maintenance costs of an air source heat pump compare to other heating systems?
- How long do air source heat pumps last?
- How noisy are air source heat pumps?
- Can air source heat pumps provide hot water?
- How complicated is installing a heat pump and how much time will it take?
- How can I maximize energy savings from my heat pump?
- I've heard that heat pumps can sometimes blow cold air?
- How much will an air source heat pump cost?
- What incentives are available?
- How does the wind/windchill affect ASHPs?
- Could there be issues with oversizing the systems?
- Do we need to be concerned about the snow?
- Can plants/bushes/shrubs be placed around the outdoor units to cover them?
- How does the planning of ASHPs positioning in difficult floor plans? Example of a condo that is set up with traditional 3 main rooms and 2-3 bedrooms.
- Can we install on unit now and more later?
- What is the life expectancy of the units?
- Will I need an electrical service upgrade?
About heat pumps
|What is an air source heat pump and how does it work?||
Air source heat pumps (ASHP) are electric appliances that provide heating and cooling by moving heat into a home or building (for heating) or out of a building (for cooling). Heat pumps do not create heat like electric resistance heating or fossil fuel-fired heating systems; instead, they move heat from one place to another. ASHPs use the outdoor air as a source of heat, while ground source (or geothermal) heat pumps use the ground as a source of heat.
They accomplish this by using a refrigerant that absorbs heat from colder air to move that heat into a space with warmer air—much the same way that a refrigerator or air conditioner works, except that it can move heat in both directions to provide both heating and cooling. Since it takes far less energy to move heat than it does to create heat, ASHPs are one of the most efficient home heating systems available.
Check out this video from Mass Save, the state's utility energy efficiency program, for a visual explanation of how ductless mini-split heat pumps work (and read on to learn more about the types of heat pumps available!).
|What types of air source heat pumps are available?||
There are two primary types of air source heat pumps (ASHPs):
Ductless heat pumps are exactly as they sound: heat pumps that don't require that you have ductwork in your home to provide heating and air conditioning. 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 can be installed as a primary source of heating and cooling or installed to heat and cool specific areas of your building. This could include, for example, installing ductless units in the most frequently used rooms like family rooms or master bedrooms to displace heating or cooling from your existing system, or placing ductless units in rooms or new additions that never seem to be warm or cool enough.
These systems can be used for heating, cooling, dehumidification or as a fan. Because each indoor unit can be controlled individually, you can reduce your energy use even more by lowering the temperature in rooms that are not being used.
Ducted heat pumps have an outdoor unit that is connected to a building's ductwork, which is used to distribute heating or air conditioning throughout the home. Ducted (also known as central or unitary) use your home’s existing ductwork, though not all ductwork is sized adequately for heat pumps. Muirfield can tell you if your ductwork is sized adequately and what modifications may be necessary during a free site visit.
Regardless of whether a system is ductless or ducted, all ASHPs will have an outdoor unit similar to that of a central air conditioner (pictured below), which will be mounted on a ground platform or on the side of your home.
Above: A ductless ASHP outdoor unit; Below: A ducted ASHP outdoor unit
This outdoor unit will be connected to one or more indoor air distribution units. If you’re installing a ducted ASHP, this will be a central air handler similar to one used by a furnace or central AC system. If you’re installing a ductless ASHP, this will typically be a wall-mounted unit (pictured below).
For homeowners that might not have suitable wall space or don’t like the aesthetic look of the wall-mounted indoor unit, floor-mounted (pictured below) units and ceiling cassettes (that look like vents in the ceiling) are also available, though these units cost more to install.
|What are the benefits of using an air source heat pump?||
There are many reasons why an air source heat pump could be a good fit for your home:
|Don’t air-source heat pumps perform poorly in cold climates?||
Traditional ASHPs are known for their poor cold-climate performance: these systems have been primarily used in the South for decades and are optimized for a warmer climate where air conditioning needs are higher.
The ASHPs installed through HeatSmart Belmont (and rebated by Belmont Light) are cutting-edge cold-climate models that are optimized for New England weather. These cold climate ASHPs are certified based on their performance at 5°F and can continue providing heat even when winter air is well below zero: today’s cold climate air source heat pumps can extract heat from the air all the way down to -13°F.
Concerned about heat pump performance in January? Don't be: Mainers and Vermonters have installed the most cold-climate heat pumps out of any New England state in the past few years—over 40,000 since 2013, and both states are significantly colder than Massachusetts in the winter!
|Are there drawbacks to air source heat pumps?||
While ASHPs are a great fit for many Belmont homes and businesses, they like other heating and cooling systems are not without a few drawbacks:
|Is an air source heat pump right for me?||
ASHPs can be installed in most homes. However, if you answer “Yes” to any of the questions below, a ductless or ducted ASHP could be a great fit for you:
|Why are air source heat pumps considered “clean heating and cooling” technologies?||
Air source heat pumps are considered to be “clean” heating and cooling systems because they do not create heat, but rather they move renewable heat from the sun in the ambient air from one place to another. This process is powered by electricity, which can also be sourced from renewable sources like solar, wind, or hydro.
Belmont’s electricity supply is 50% renewable today and is getting greener each year. With today's grid electricity, an ASHP system will reduce your greenhouse gas emissions from heating by 40-80% depending on the fuel you're replacing!
|How efficient are air source heat pumps?||
ASHPs are typically rated for heating efficiency based on their Heating Seasonal Performance Factor (HSPF) or seasonal Coefficient of Performance (COP), both of which describe the system’s efficiency over the course of the heating season. The seasonal efficiency of ASHPs can range from 220% to 300%+ (i.e. COP of 2.2 to 3.0) depending on the system type, application, and how cold it is outside. That means that for every one unit of electricity used, 2.2 to 3 units of heat are transferred into the home. By comparison, electric resistance heating has a COP of 1, and many fossil fuel boilers and furnaces are 80% efficient. Even the most efficient models will never be more than 98% efficient.
ASHPs also provide high-efficiency cooling—better than window AC units and comparable to the highest-efficiency central air conditioners.
|How do the annual maintenance requirements and costs of an air source heat pump compare to other heating systems?||
Annual system maintenance, which consists of cleaning air filters and an annual maintenance checkup for the outside unit, costs about the same as annual servicing charges for a boiler or furnace. You can also clean the filters yourself, which can help to keep your system running well for many years (ask Muirfield for tips on how best to do this!), though it is worth having a professional inspect your equipment.
Otherwise, the only other maintenance requirement would be to keep your outdoor unit clear of snow during the winter.
|How long do air source heat pumps last?||Heat pumps have an expected lifetime of about 15 years—similar to the average furnace or central AC system.|
|How noisy are air source heat pumps?||
A ductless ASHP indoor unit is "whisper-quiet"—quieter than a refrigerator and much quieter than a typical window AC unit. A ducted ASHP can be quieter than a typical furnace or central air conditioner.
The outdoor unit will make a similar amount of noise to a central AC unit during operation. Occasionally during the winter, the outdoor unit will briefly operate in "defrost mode" to keep the unit clear of any frost buildup and keep airflow constant. Switching into defrost mode can make a brief whooshing noise.
|Can air source heat pumps provide domestic hot water?||
Most don't. There are water heaters that use heat pump technology (heat pump water heaters or HPWHs), though they are considered different technologies than ASHPs and are not included in the special HeatSmart Belmont offer.
|How complicated is installing a heat pump and how much time will it take?||
A heat pump installation is typically a straightforward process with minimal disruption to your home. A simple, single-zone ductless ASHP system can be completed in less than a day and only requires a single 2-3 inch hole to be cut (and later, sealed) in your wall.
If you are installing a “multi-zone” ductless system or a ducted system that requires modifications to your ductwork, your installation may take a few days or more to complete.
|How can I maximize energy savings from my heat pump?||
While ASHP systems will run well as soon as they're installed, there are a few things you may want consider to get the most out of your system:
|I've heard that heat pumps can sometimes blow cold air?||
A properly-functioning heat pump may occasionally blow air that feels cooler than expected, particularly relative to a furnace. There are two reasons this may occur:
If your heat pump is providing inadequate heat, you may consider using your backup system during temperature extremes (or improving the insulation of your home). If your heat pump continues to blow cold air, you may have a maintenance issue with your system and should contact an installer.
|How much will an air source heat pump cost?||
Air source heat pump systems typically start at around $4,000-4,500 before incentives for a single-zone unit, increasing with additional zones and if you are interested in using a heat pump as your primary source of heat.
Stay tuned: once we have finished our selection process, we'll post the special pricing Muirfield will be offering through HeatSmart Belmont.
|What incentives are available?||
Belmont Light offers rebates for cold climate heat pumps ranging from $650-$1,500, with extra rebates if you have receive the Residential Rate A Low-Income or Small Municipal Rate MB or fully replace fossil fuels in your home. Learn more about Belmont Light's rebates and submit an application here.
|How does the wind/wind chill affect ASHPs?||
The wind chill affects the effectiveness of the ASHPs by impacting the overall thermal envelope of the house. A tighter envelope means the wind chill will not reduce the heat as much and the ASHPs will not have to work as hard for the same level of heat.
There may be some issues with the drip pan, but the defrost cycle should help keep the outside unit clear.
|Could there be issues with oversizing the systems?||
Oversizing heating systems in general can reduce efficiency and comfort. Our installer, Muirfield Mechanical, will perform the load calculations needed to determine the proper sizing of a heat pump system when it is expected to serve as a primary source of heating.
Compared to other heating systems, air source heat pumps are variable speed, which means they can reduce the amount of heating or cooling provided to meet the needs of the space. The modulation of the heat pump improves its efficiency and occupant comfort..
|Do we need to be concerned about the snow?||Outdoor units are mounted on ground stands that are at 12”, 18” and 24” high. If the outdoor unit is mounted high enough, nothing needs to be done to clear the area around the outdoor unit, though it can be valuable to ensure that snowdrifts are not building up around the unit during your first snowstorm to make sure. If snow does get into the outdoor unit and causes an issue, there are automatic sensors to detect the resistance and shut down the fans.|
|Can bushes or shrubs be placed around the outdoor units to cover them?||Yes, as long as sufficient space is left around the outdoor unit to allow for the air to circulate. Examples can be found on Nantucket due to historic district restrictions.|
|How does the planning of ASHPs positioning in difficult floor plans with a lot of small rooms?||Ductless units can be installed within a central area or room, and air can be moved from that room to other adjacent rooms using heat transfer fans installed in the walls. The fans move the air from the room with the indoor unit to the non-installed room to keep it at the set temperature. Ducted units will rely on the existing ductwork to distribute air throughout the space, though modifications (or use of mini-ducted units) can help to improve distribution of heating and cooling.|
|Can we install one unit now and more later?||Yes, you can always add additional single-zone ductless units, though if you are installing a multi-zone unit, additional units can be added up to the maximum number of units as long as the capacity is sufficient. If you are interested in this approach, Muirfield recommends installing at least 2 indoor units, which allows for better future capacity planning and enables the systems to perform more efficiently.|
|What is the life expectancy of the units?||Typical lifespan of a heat pump is 15-18 years, which is the same as a typical furnace or central air conditioner. As a Diamond Dealer, Muirfield’s warranty for Mitsubishi systems covers 12 years parts and labor.|
Will I need an electrical service upgrade?
|If you have 100-amp electrical service you may need an upgrade, depending on the size and type of heat pump you’re installing and what electric appliances (e.g. central air conditioning, water heating, electric baseboards, stove, dryer, etc.) you currently have. In particular, most homes with 100-amp service will likely require upgrading to 200-amp service for a larger multi-zone or whole-home system. If your electrical service is sufficient but your circuit breakers are full, you may need to add a subpanel to make room for the heat pump.
If you already know what your home's electrical service capacity is, ask Muirfield about it when they call you to schedule a free site visit. Once on-site, Muirfield will assess the current state of your electrical service and make recommendations regarding whether an upgrade might be needed for the heat pump solution that meets your needs.
About HeatSmart Belmont
|How did HeatSmart Belmont select Muirfield?||
The HeatSmart Belmont team held a competitive, open selection process led by the core volunteer team. The Belmont team reviewed bids from four qualified installers, analyzed available data sources, and held interviews with the installers with support from MassCEC and third-party technical experts.
The Belmont Team selected Muirfield Mechanical for a number of reasons, including but not limited to: Muirfield's knowledge and expertise with heat pumps and building energy usage more broadly; experience with installing systems in homes in Belmont; familiarity with obtaining rebates and financing through the Home MVP Pilot Program; and competitive and transparent pricing.