The Mass Save HEAT Loan Explained: 0% Financing for Boston Heating Upgrades

What is the Mass Save HEAT Loan?

The Mass Save HEAT Loan is a 0% interest financing program that helps Massachusetts residents pay for energy-efficient home improvements. Mass Save — the statewide energy-efficiency initiative funded by Massachusetts utility ratepayers and sponsored by utilities like Eversource, National Grid, and Unitil — buys down the interest to zero, while a network of participating banks issues and services the actual loan. The result for you: you spread the cost of a major upgrade over several years and pay back only what you borrowed, with no interest added.

For Greater Boston homeowners, this matters because so much of the region's housing stock — triple-deckers, brownstones, and Victorian-era homes — runs on aging boilers and furnaces that are expensive to replace out of pocket. The HEAT Loan turns a large one-time cost into a manageable monthly payment.

How much can you borrow, and what's the interest rate?

As of 2026, the Mass Save HEAT Loan offers 0% APR financing up to a maximum of $25,000, with repayment terms commonly up to seven years (84 months). There are no origination fees, no closing costs, and no prepayment penalties. The $25,000 cap applies over the lifetime of your energy-efficiency upgrades, so once you've financed measures totaling that amount, you've reached the limit.

One detail worth knowing: while the interest rate is always 0% regardless of your income, your household income can affect the length of the repayment term you're offered. Lower-income households may qualify for longer terms and smaller monthly payments.

Who is eligible for the Mass Save HEAT Loan?

Eligibility for the Mass Save HEAT Loan generally requires that you are a residential customer of a participating Massachusetts utility (such as Eversource, National Grid, Unitil, Cape Light Compact, Berkshire Gas, or Liberty Utilities), that your project involves qualifying energy-efficiency upgrades, and that the work is recommended through a no-cost Mass Save Home Energy Assessment and installed by a participating contractor. Final loan approval is handled by the participating lender based on your creditworthiness.

For Boston-area homeowners, the practical takeaway is that your utility account is the starting point. If you receive a gas or electric bill from one of the sponsoring utilities, you're likely in the eligible pool — the assessment confirms the specifics for your home.

What does the HEAT Loan cover?

The HEAT Loan covers a wide range of energy-efficiency improvements, not just heating equipment. Qualifying measures typically include air-source and ground-source heat pumps, heat pump water heaters, insulation and weatherization, ENERGY STAR-certified replacement windows (when done alongside recommended weatherization), and residential battery storage enrolled in the ConnectedSolutions program.

Every measure must be recommended during your Home Energy Assessment and installed by a Mass Save participating contractor. For heat pump projects specifically, the installer must belong to the Mass Save Heat Pump Installer Network (HPIN), and the equipment must appear on the Heat Pump Qualified Product List. Note that as of 2026, systems using older R-410A refrigerant are no longer eligible — only next-generation refrigerants such as R-32 and R-454B qualify.

How do you apply for the Mass Save HEAT Loan?

Applying for the HEAT Loan follows a clear sequence: first, schedule a no-cost Mass Save Home Energy Assessment, which produces the list of recommended upgrades that make your project eligible. Next, get a proposal from a participating contractor for the recommended work. You then submit a HEAT Loan application to a participating lender along with your contractor's proposal and the required Mass Save documentation. Once approved, you receive an authorization form — and it's important to have that in hand before work begins.

The single most common mistake homeowners make is starting work before completing the assessment and approval steps, which can jeopardize eligibility. The assessment always comes first.

How does the HEAT Loan work with Mass Save rebates?

The HEAT Loan is designed to work alongside Mass Save rebates, not instead of them. In 2026, Mass Save offers whole-home air-source heat pump rebates of up to $8,500 (calculated at $2,650 per ton), with substantially higher incentives for income-qualified households. Those rebates reduce your project cost directly — and the HEAT Loan can then finance your remaining net cost at 0% interest.

In practice, a homeowner replacing an aging system might apply the rebate to knock several thousand dollars off the price, then use the 0% HEAT Loan to spread the rest over several years. One important 2026 update: the federal tax credits that previously helped offset heat pump costs (the 25C and 25D credits) expired at the end of 2025, which makes the state-level Mass Save rebate and HEAT Loan even more central to affording an upgrade. For a full breakdown of the rebates themselves, see our guide to Mass Save heat pump rebates in Boston.

Is the Mass Save HEAT Loan worth it for Boston homeowners?

For most Boston homeowners facing a heating upgrade, the HEAT Loan is worth serious consideration because it removes the biggest barrier to going high-efficiency: the upfront cost. Financing a $15,000 project at 0% instead of on a credit card or a conventional home-improvement loan can save thousands of dollars in interest over the life of the loan. Combined with Mass Save rebates, it can bring a modern, efficient system within reach for homes that have relied on decades-old boilers.

The catch is that the process has specific steps and requirements — the assessment, qualified equipment, network-participating installers, and lender approval — and getting any of them out of order can cost you the incentive. That's where working with the right professional matters. Boston Climate Co. connects Greater Boston homeowners with licensed, HPIN-enrolled heating specialists who handle these programs regularly and can guide a project so it stays eligible from start to finish. If you're weighing a heating upgrade, our heating services page is a good next step, and our Boston HVAC cost guide can help you set expectations on price.