A heat pump for a triple-decker
One boiler for three floors, or three systems under one roof. The heat pump answer starts with how the building is heated and metered today.
- Checked: November 3, 2026
Two ways it goes
- One system per floor. Each unit gets its own outdoor unit and indoor heads or air handler. Each tenant or owner can control their own heat.
- One shared plant. One larger system serves the building, replacing the central boiler. The owner decides, and the heat is still shared.
Mass Save's whole-home rebate is $2,650 per ton up to $8,500 for a 2026 install, and the equipment must be in an individually metered 1-4 unit building. For a building with separate meters, that points to a system per floor. Check it with Mass Save.
Where the triple-deckers are
Share of all housing units that sit in buildings of two to four units, for the towns on this site with the highest share.
| Town | In 2-4 unit buildings | Owner-occupied homes |
|---|---|---|
| Somerville | 55% | 34% |
| Everett | 53% | 37% |
| Watertown | 43% | 48% |
| Salem | 38% | 50% |
| Belmont | 38% | 65% |
| Boston | 35% | 36% |
The low owner-occupied share in these towns is why so many projects are landlord decisions. Read about the service, meters and wiring in these buildings, and the panel upgrade that often comes with a heat pump.
What to send
- A photo of each boiler or heating unit.
- The meter bank and each unit's panel, door open.
- Whether you own the building, live in one unit or rent.
Common questions
Can I put a heat pump in just my floor of a triple-decker?
Often yes, if you control your own heat and meter. A shared boiler is different: the owner decides, and a tenant should talk to the landlord. Choose "I rent" in the request form so we know.
How many heat pumps does a three-family need?
That depends on the layout and the heat load of each floor. We size each unit. Photos of every boiler and every panel help.
Does Mass Save pay for each unit?
Mass Save says the whole-home rebate needs equipment in an individually metered 1-4 unit building. How your building and meters are treated is a question for Mass Save and your installer.
Own a two- or three-family?
Send a photo of each boiler and the meter bank. We look at them and get back to you.
Send photos