A Whole-Home Heat Pump System for a Bedford, MA Home With No Easy Answers
A 100-year-old steam boiler in front, forced hot water in the addition, window AC units in summer, and the homeowners wanted whole-home comfort, lower bills, and a $4,682 Mass Save rebate. Here’s how Pespisa Company designed a hybrid Mitsubishi heat pump system that fit the home instead of fighting it.
When this Bedford, MA family called Pespisa Company, they already knew what they wanted: efficient whole-home heating and cooling, and the Mass Save rebate they’d been pre-qualified for. What they did not have was a clean, easy install. Their home was running on three different climate systems a steam boiler in the original front of the house, forced hot water baseboard in the rear addition, and window AC units shoved into windows for the summer. There was no central ductwork to reuse and no single distribution method that would serve every room well.
Most contractors would have either pushed an all-ductless solution and put a wall unit in every bedroom, or politely turned the job down. Instead, we designed a hybrid ducted-and-ductless Mitsubishi heat pump system built specifically for the way this house is laid out, and for the way the family actually uses it.
The Challenge
Three climate systems, none of them working together
The home had a long history of comfort compromises:
- A steam boiler kept the front of the house warm in the winter old, but still working.
- A forced hot water baseboard loop served the rear addition, on a separate zone.
- Window AC units were the only summer cooling option, swapped in and out each year.
The result was uneven comfort, high energy use, and a setup that didn’t qualify for the long-term efficiency upgrades the family wanted. They had already completed a Mass Save home energy assessment and were pre-approved for the rebate program, so the system we designed had to qualify on the first pass.
Our Solution
A hybrid Mitsubishi heat pump system, sized to the home
We installed a two-outdoor-unit Mitsubishi heat pump system with five indoor units four wall-mounted ductless heads in the spaces where short installs and clean lines mattered, plus a hidden ducted indoor unit in the attic feeding the smaller front bedrooms and bath through brand-new sealed ductwork.
Two outdoor heat pumps:
- Mitsubishi MXZ-3D24NL (24,000 BTU / 2 tons)
- Mitsubishi MXZ-4D30NL (30,000 BTU / 2.5 tons)
Five indoor units, matched to each space:
- MSZ-GX12NL — master bedroom (ductless wall)
- MSZ-GX15NL — first-floor front room (ductless wall)
- MSZ-GX12NL — living room and kitchen (ductless wall)
- MSZ-GX06NL — fireplace room (ductless wall)
- SVZ-AP12NL — attic-mounted ducted unit serving front bedrooms and bath
Controls: three Ecobee Smart Thermostats paired with the Mitsubishi PAC-USWHS002-WF-2 integrated controller a Mass Save rebate requirement, and a much better day-to-day experience than the standard remote.
Backup heat: the existing steam boiler and forced hot water systems were left in place. The heat pumps do the daily work, but the family keeps the redundancy of two existing fuel sources for the coldest winter days.
Why This Design Was the Right Fit
A single distribution method couldn’t have served this home well. Pushing wall heads into every bedroom would have looked cluttered and worked poorly in the smaller front rooms. Trying to run new ducts everywhere would have been invasive in a home with finished plaster and original details.
The hybrid approach gave the family the best of both:
- Ductless where it made sense — open living spaces and the master bedroom, where short refrigerant line runs preserved finishes and the wall units actually look intentional.
- Ducted where it mattered — the smaller front bedrooms and bath are served quietly from a single attic-mounted indoor unit through new insulated ductwork, with no wall heads visible in those rooms.
- Two outdoor units sized so each side of the home gets matched capacity, instead of one oversized unit running inefficiently.
Full Mass Save eligibility — integrated controls, qualifying equipment, and a complete whole-home design that hit the rebate program’s requirements.
The Result
The family now has whole-home heating and cooling from two efficient Mitsubishi heat pumps, with three-zone Ecobee control and a much quieter, cleaner system than what was there before. The original boiler systems are still in place as backup heat for the coldest days, so they have redundancy without paying to maintain two duplicate systems.
Highlights:
- $4,682 Mass Save rebate earned on the install
- 0% Mass Save HEAT Loan financing eligibility up to $25,000
- Whole-home cooling for the first time in this home’s history — no more window units
- Three-zone control with Ecobee + Mitsubishi integrated thermostats
- Cleaner aesthetics — wall heads only where they made sense, hidden ductwork everywhere else
Existing heat retained as backup, not ripped out
System | Mitsubishi hybrid ducted + ductless heat pump |
Total capacity | ~54,000 BTU / 4.5 tons across two outdoor units |
Outdoor units | MXZ-3D24NL, MXZ-4D30NL |
Indoor units | MSZ-GX12NL ×2, MSZ-GX15NL, MSZ-GX06NL, SVZ-AP12NL (ducted) |
Controls | Ecobee Smart Thermostat ×3 + Mitsubishi PAC-USWHS002-WF-2 |
Backup heat | Existing steam boiler and forced hot water baseboard retained |
Distribution | ~500 sq ft of new sealed and insulated ductwork |
Permit | Sheet metal permit pulled with Town of Bedford |
Warranty | Standard Mitsubishi manufacturer warranty |
Mass Save rebate | $4,682 |
Financing | Eligible for 0% Mass Save HEAT Loan up to $25,000 |
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Mass Save Made This Easier — and Cheaper
This system qualifies for $4,682 in Mass Save rebates and up to $25,000 in 0% Mass Save HEAT Loan financing. If you live in Massachusetts and you’ve had a recent Mass Save assessment, we can design your system to meet the rebate requirements right out of the gate.
