Learn More About ASHPs

1.What is an air-source heat pump?

Heat naturally moves from warmer places to cooler places. Heat pumps use electricity to move heat in the opposite direction, from cooler places to warmer places, making the cool space cooler and the warm space warmer. Your refrigerator is a heat pump, moving heat from inside the refrigerated cabinet (cooler place) into your kitchen (warmer place). An air conditioner is a heat pump, moving heat from inside your home (cooler place) to the outside summer air (warmer place).

Heat pumps are also used to heat homes, taking advantage of the fact that in the spring, fall, and yes, even in the winter, there is some heat in the outdoor air. An air-source heat pump collects heat from the outdoor air, concentrates it via an outdoor compressor, and distributes it inside through an indoor room unit or a home’s ductwork. During the summer, a heat pump can operate in reverse, as an air conditioner, by moving heat from indoors to the outside air.  Heat pumps require electricity to run, but can deliver more energy than they use.

Air-source heat pumps have been used for many years in nearly all parts of the United States, but until recently they have not been used in areas that experienced extended periods of subfreezing temperatures. However, in recent years, air-source heat pump technology has advanced so that it now offers a legitimate space heating alternative in colder regions. Over 300,000 heat pumps were sold in New England, New York, New Jersey, Pennsylvania, Delaware, Maryland, and Washington DC in 2015 alone.

2.What is the advantage of installing an air-source heat pump in my home?

The majority of people who install an air-source heat pump in their home do so to obtain an improved level of comfort. For example, they may wish to add air conditioning to a home, or to better heat or cool parts of their home that weren’t adequately heated or cooled before. And, popular ductless heat pumps installed throughout a home are zone-friendly – you heat or cool only the rooms you need to.

People who currently have conventional electric resistance or propane-fueled heating systems can save 50% - 70% on energy costs by heating with an air-source heat pump instead. At current fuel prices, oil heating households can save up to 30%. At current prices, natural gas-heating households won’t cut costs by using air source heat pumps.

Concordians also install heat pumps because the systems reduce carbon emissions due to heating by 30 – 70%. This is a result of the combined high efficiency of the heat pump technology and the relatively lower carbon content of electricity, compared to other heating fuels. Most households keep their existing heating system when they install heat pumps. On extremely cold days, the existing heating system supplements the heat provided by the heat pumps. The actual percentage of carbon reduction depends on the percentage of the home’s heating needs met by heat pumps, and the heating fuel being replaced.

3.What does an air-source heat pump look like?

Cold climate air-source heat pumps come in two varieties: ductless and ducted.

Ductless heat pumps, also known as mini-splits, have outdoor compressors and indoor wall, floor, or ceiling mounted units to distribute the warm or cool air. Because ductless heat pumps do not require the presence of air ducts, they can be installed in homes currently heated with a boiler or an electric baseboard heating system. 

ASHP Outdoor UnitASHP Indoor Unit


Outdoor and indoor components of a ductless ASHP system in Concord, MA

A central ducted heat pump can be installed in homes with air ducts. It looks and performs like a central air conditioning system, except that it can heat in winter as well as cool in summer. 

  Heat Pump Outdoor Unit  Heat Pump Indoor Unit  

Outdoor and indoor components of a ducted heat pump system in Carlisle, MA

Whether you choose ductless or ducted heat pumps depends on the characteristics of your home.

DuctedDuctlessHP Presentation--2017-02-04 7

4.How can I learn more about air-source heat pumps?

CMLP can put you in touch with Concord residents who have already installed heat pumps in their homes, and who would be happy to share information about their experience buying and using a heat pump. Contact Energy Specialist Pamela Cady at pcady@concordma.gov or 978-318-3149 for referrals.

5.How can I learn about the best air-source heat pump options for my home?

We suggest soliciting proposals from at least three heat pump installers. Before soliciting proposals, consider talking with Concord residents who have already installed heat pumps in their homes. CMLP’s Energy Specialist, Pamela Cady (pcady@concordma.gov or 978-318-3149), can put you in touch with Concord residents who would be happy to share information about their experience buying and using a heat pump.

CMLP strongly suggests that you seek proposals from HVAC (Heating, Ventilation and Air Conditioning) contractors who can provide a letter or certificate from the manufacturer verifying that the installer has successfully completed at least 4 hours of manufacturer training within the last 5 years for the products they install. CMLP highly recommends that you request the installer submit this documentation to you with their proposal. The documentation will be required if you wish to apply for a CMLP rebate for your heat pump.

The following HVAC contractors have installed air conditioning and/or heat pump systems for Concord residents who have received energy efficiency rebates from CMLP in the past. CMLP does not have any knowledge of customer experiences with these vendors, and we do not endorse, nor have we pre-qualified these companies in any way. When requesting a proposal from a contractor, CMLP recommends asking for the documentation of the manufacturer training described above.

HVAC Contractors with experience in Concord
City, State, Zip
A & R Mechanical, Inc.
Lunenberg, MA 01462
A Fagundes
Lowell, MA 01851
Absolute Mechanical Systems
Brookline, NH 03033
Achieve Renewable Energy
Woburn, MA 01915
Acton Refrigeration
Littleton, MA 01460-2015
Advanced Mechanical Systems
Stow, MA 01775
Airco Home Comfort Svcs.
Watertown, MA 02472
All-Temp Systems
Milford, MA 01757
Ayotte Plumbing Heating AC
North Chelmsford, MA 01863
Basnett Plumbing and Heating, Inc.
Littleton, MA 01460
Bedford Mechanical
Bedford, MA 01730
Bill Wenzel Heating & Air Conditioning
Merrimack, NH 03054
Boucher Energy Systems, Inc.
Mendon, MA 01756
Bursaw Gas & Oil, Inc.
Acton, MA 01720
Central Cooling and Heating, Inc.
Woburn, MA 01801
Chaves Heating and Air Conditioning
Hudson, MA 01749
Climate Engineering LLC
Abington, MA 02351
Concord Heating & Air Conditioning, Inc.
Concord, MA 01742
CoolAir Company
Dracut, MA 01826
Cranney Home Services
Danvers, MA 01923
Druziako HVAC
N. Chelmsford, MA 01863
East Coast Metals
Pepperell, MA  01463
Eric C. Foster Plumb., Htg, Cool
Chelmsford, MA 01824
Genove Oil & Air Company, Inc.
Waltham, MA  02453-4113
George Akhian HVAC
Lexington, MA 02421
HillCO Heating and Cooling, Inc.
Littleton, MA  01460
J & J Heating and Air Conditioning, Inc.
Dracut, MA  01826
Jay Moody LLC
Leominster, MA 01453
Keyes North Atlantic
Newton, MA 02460-1451
Lamco Systems
Tyngsboro, MA  01879
MacCormack Plumbing
Billerica, MA  01821
Mancini Heating and Cooling
Billerica, Ma  01821
Mass Mechanical Co. Inc.
Framingham, MA 01701
Melendy and Sons, Inc.
Pepperell, MA 01463
Muirfield Mechanical Services, LLC
Boxborough, MA 01719
Nashoba Sheet Metal Inc.
Westford, MA 01886
Obie Comfort Solutions
Framingham, MA 01702
Papalia Plumbing and Heating
Acton, MA  01720
RER Fuel Service, Inc.
Billerica, MA 01862
Rodenhiser Heating and Cooling
Holliston, MA  01746
Royal Air Systems, Inc
North Reading, MA
S C Mechanical Services
Hollis, NH 03049
S.G. Torrice
Wilmington, MA 01887
Suburban Sheet Metal, Inc.
Norwood, MA  02062
Tag Heating and Cooling
Ayer, MA 01432
The Fisher-Churchill Co.
Dedham, MA  02026
Thermoil, Inc.
Watertown, MA 02471-0042
Total Temperature Control Inc.
Wakefield, MA 01880
Unique Indoor Comfort Heating & Cooling
Woburn, MA 01801
Wilson Brothers HVAC, Inc.
Pepperell, MA 01463
Winters Company Plumbing and Heating
Cambridge, MA 02138
Wrightway Heating and Cooling Corp
Ayer, MA 01432

6.What questions should I ask potential air-source heat pump installers?

Consider asking potential installers the following questions:


  1. Can you provide references from previous customers with similar systems?
  2. Can you provide a letter or certificate verifying that your installation staff has participated in at least 4 hours of manufacturer training in the last 5 years for the systems you would install in my home?


  1. Ductless and centrally ducted heat pumps that qualify for a MassCEC rebate in communities served by investor-owned utilities will qualify for a CMLP rebate (but not a MassCEC rebate) here in Concord.  Do you install systems that qualify for MassCEC rebates in other towns?
  2. Centrally ducted heat pumps on NEEP’s (Northeast Energy Efficiency Partnership’s) Cold Climate Air Source Heat Pump Specification Listing qualify for a CMLP rebate. Do you install centrally ducted systems that are on NEEP’s Cold Climate Air Source Heat Pump Specification Listing? (Note: A centrally ducted heat pump is an option only in homes that have existing air ducts, or in new homes that will have air ducts once constructed. This question is not relevant to homes without air ducts.)
  3. Are you familiar with the application process for CMLP’s air source heat pump rebate and are you willing to complete the process for me?

Installation Process

  1. When would you be able to perform the installation and how long will it take to complete?
  2. Will you hire subcontractors to complete portions of the project? If so, what firms and what will they do?
  3. Will you provide training for me on how to properly operate and maintain the system?
  4. Do you provide a warranty for the systems you install?