Mass Save ground source heat pumps rebates
For HVAC contractors filing on behalf of a residential customer.
Ground source heat pumps carry the largest Mass Save residential heat pump rebate, up to $13,500 per home. The whole-home and partial-home split works the same way as air source, but the rates, the equipment list and the multi-family rules differ.
3 open questions on this pathway
The official documents disagree or are silent on the points below. We show them rather than picking a reading, and this is why this pathway is not check-supported.
- Whole-home rebate. The form's rebate table gives partial-home a per-ton rate but shows only a cap for whole-home, with no rate and no stated basis for calculating the award. The program page's cost example shows a $13,500 whole-home rebate on a $44,000 installation, which is the cap rather than a formula. Ask the administrator how a whole-home ground source award is actually computed.
- Filing deadline. The program page says documentation must be RECEIVED BY 28 February 2027; the form's Terms and Conditions say applications must be POSTMARKED BY that date. The same contradiction appears in the air source and Basic forms.
- Equipment list. The rebate table on the ground source form points to the ENERGY STAR certified list, while the Terms and Conditions on the same form carry the air source boilerplate requiring the Mass Save Heat Pump Qualified Product List. The program page cites ENERGY STAR Cold Climate and the HPQPL. Confirm which list governs a ground source unit before relying on either.
Rebate amounts
| What | Value in this edition | Source |
|---|---|---|
| Partial-home rebate | $2,000 per ton, up to $13,500 per home | S6 |
| Whole-home rebateThe form's rebate table gives partial-home a per-ton rate but shows only a cap for whole-home, with no rate and no stated basis for calculating the award. The program page's cost example shows a $13,500 whole-home rebate on a $44,000 installation, which is the cap rather than a formula. Ask the administrator how a whole-home ground source award is actually computed. | Unresolved Up to $13,500 per home — the per-ton rate is not stated | S6 |
| How a ton is measured | AHRI cooling capacity ÷ 12,000 BTU | S5, S6 |
| Limit | One whole-home rebate per home. Partial-home rebates capped at $13,500. | S6 |
| Ceiling | Rebate may not exceed the total installation cost | S5, S6 |
Dates and deadlines
| What | Value in this edition | Source |
|---|---|---|
| Installation window | 1 January 2026 to 31 December 2026, inclusive | S5, S6 |
| Filing deadlineThe program page says documentation must be RECEIVED BY 28 February 2027; the form's Terms and Conditions say applications must be POSTMARKED BY that date. The same contradiction appears in the air source and Basic forms. | Unresolved 28 February 2027 — but the rule for meeting it is unresolved | S5, S6 |
| Payment processing | 6–8 weeks after an approved submission | S6 |
Eligibility
| What | Value in this edition | Source |
|---|---|---|
| Sponsor and fuel | Residential customer replacing oil, propane or electric resistance where Cape Light Compact, Eversource, National Grid or Unitil is the electric sponsor; or replacing natural gas where Berkshire Gas, Eversource, Liberty, National Grid or Unitil is the gas sponsor. | S5, S6 |
| Equipment listThe rebate table on the ground source form points to the ENERGY STAR certified list, while the Terms and Conditions on the same form carry the air source boilerplate requiring the Mass Save Heat Pump Qualified Product List. The program page cites ENERGY STAR Cold Climate and the HPQPL. Confirm which list governs a ground source unit before relying on either. | Unresolved Refer to the ENERGY STAR certified list | S6 |
| Multi-family | Apart from townhouses, customers in buildings of five or more units are not eligible for the whole-home rebate. Weatherization is not required for 5+ unit buildings. | S5, S6 |
| Whole-home: weatherization and verification | Home sufficiently weatherized before installation, demonstrated by any one of (A) built during or after 2000, (B) Home Energy Assessment recommends under $1,000, (C) recommendations made during or after 2013 completed. Whole-Home Heat Pump Verification Form completed and signed. | S5, S6, S3 |
| Whole-home: sole heating source | Heat pumps must be the sole source of heating during the heating season. | S6 |
| Existing heat pumps | Replacing an existing heat pump does not qualify for whole-home or partial-home. It may qualify for the Basic rebate. | S5 |
| Occupancy and combination | Full-time winter occupancy required. Not combinable with other Mass Save incentives for the same equipment, except the HEAT Loan. Not available for new construction or major renovation. | S5, S6 |
Document checklist
| Document | What it must show | Source |
|---|---|---|
| Completed and signed rebate form | The ground source form, revision 0078_GSHP_12.25. | S6 |
| Installer invoice | From an HPIN installer, showing installer name and address, outdoor and indoor model numbers, installation date, installation address and total install cost per system. | S6 |
| Proof of payment | Accompanying the invoice. | S6 |
| Whole-home Heat Pump Verification Form | Whole-home only. The same form the air source pathway uses, signed by both the customer and the HPIN installer. | S6, S3 |
Equipment evidence
The form captures the AHRI Certified Reference number, AHRI cooling capacity in BTU, the resulting tons, install date and area served. Which qualified-product list governs is unresolved — see the eligibility table.
Installer requirement
Installation must be completed by a contractor participating in the Mass Save Heat Pump Installer Network, and the whole-home verification form requires that installer's own signature.
Where the application goes
File online at MassSave.com/Savings, or mail to Mass Save Residential Heating and Cooling Program, 1337 Massachusetts Ave, PO Box #228, Arlington, MA 02476.
Sources
Every fact above cites one of these by id. Each was retrieved and hashed on the date shown; we link the official document rather than restating it.
| Id | Document | Retrieved | SHA-256 |
|---|---|---|---|
| S5 | Mass Save ground source heat pumps program page | 2026-09-07 | defa2d6e03cc4e5a… |
| S6 | 2026 Residential Ground Source Heat Pump Rebate FormRevision 0078_GSHP_12.25 | 2026-09-07 | 91e66c113a2c674d… |
| S3 | 2026 Whole-home Heat Pump Verification FormRevision 0078_WHV_12.25 | 2026-09-07 | 053d011fe6d005f9… |
Administered by
The Sponsors of Mass Save (Berkshire Gas, Cape Light Compact, Eversource, Liberty, National Grid, Unitil)
Where it applies
Massachusetts. Customers of Berkshire Gas, Cape Light Compact, Eversource, Liberty, National Grid, Unitil.
Confirm the customer's actual sponsor. A ZIP code does not establish service territory.
Official source
Mass Save official program page
Last confirmed to resolve 2026-09-07. The program administrator decides eligibility and payment.
Read the requirements and checklist
RebateBench is in private pilot and no pathway is packet supported yet. If this is a program you file, we would like to verify it with you.
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