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Meet the Team Behind the Mission

Our Leaders

At SumZero, we don’t believe in titles for the sake of hierarchy — we believe in leadership that serves. The people below don’t just oversee operations — they solve problems, build teams, and protect the promises we make to customers.

From the office to the warehouse to the field, these are the faces you can count on — the people who help make SumZero one of the most trusted heat pump companies in Massachusetts.

Leadership Team

Co-Owner
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David Sampaio

David Sampaio

Co-Owner

Field-focused, results-driven, and committed to excellence on every project.

Co-Owner
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Ilija Crnobrnja

Ilija Crnobrnja

Co-Owner

Vision-led leader guiding our mission, marketing, and customer experience.

Comfort Consultant
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Raphael Guimaraes

Raphael Guimaraes

Comfort Consultant

Brings clarity and trust to every estimate — a straight-shooter and system thinker.

Finance Manager
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Keven Xavier

Keven Xavier

 Finance Manager

Keeps our books tight and our strategy sharp. Numbers with integrity.

Executive Assistant & HR Manager
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Marjory Ramos

Marjory Ramos

Executive Assistant & HR Manager

The glue behind the scenes — organized, dependable, and deeply caring.

Project Manager
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Jackson Carvalho

Jackson Carvalho

Project Manager

Makes the job flow — clear scheduling, clear expectations, and no loose ends.

Warehouse Manager
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David Teran

David Teran

Warehouse Manager

Keeps our gear, our people, and our inventory moving smoothly every day.

Install and Mass Save® Coordinator
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Lara Cosendey

Lara Cosendey

Install and Mass® Save Coordinator

Juggles logistics with heart — a calm voice and steady hand behind the scenes.

Keeps the rebate process moving and the details buttoned up.

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Mass Save Concierge on Rebates and Financing

What Local Homeowners Are Saying

See how SumZero has helped local homeowners stay comfortable year-round with energy-efficient heat pump solutions.

UPDATE: It's been about 3 months since my new heat pump and gas furnace were installed and things have been humming along, moving seamlessly from cooling to heating. When the temps dropped close to 20 a couple of weeks ago though, the heat pump began to work a little harder and longer at squeezing heat from the frigid air (as we knew it would). So I looked to boost the BTU's by firing up the furnace. Though the blower came on, there was no gas, no flame. A check of the gas line valve and the circuit breaker all looked good. Working different modes on the thermostat I tried multiple times, but the furnace remained cold. I gave SumZero customer support a call first thing Monday morning and got voicemail. Though the message proclaimed my "call was important," my heart sank a little wondering WHEN I would hear back. But Lara cheerfully got back to me within the hour and said she would have a technician by the name of Dan Jameson out to the house between 1:00 and 3:00. Dan arrived a little before 2:30 with the same sunny disposition that seems to be part of the culture at SumZero. He invited me to shadow him and learn a little bit more about my HVAC system while he checked it out. He quickly discovered that an internal gas valve was in the off position, something town inspectors like to see when heating is not required (though it really isn't necessary). Needless to say, the furnace began working like a champ. Dan also took time to check the filter, the heat pump, and program the thermostat, all the while answering my questions and giving me valuable pointers as well. Now when the weather drops below freezing, the heating automatically kicks over to the gas furnace. Should any other questions come up, Dan made a point of saying to be sure to call and, if need be, they'd be happy to come out to the house to explain. Once again, everything is working as it should. And SumZero rocks! Though you try to get some idea of who you are hiring through online reviews and asking the right questions (if you even know what questions to ask), a lot of blind trust goes into choosing a contractor - trust that you'll get what was agreed to, on time, in working order, and at the right price.  I'm happy to say that SumZero checks all the boxes - and then some.  From sales rep Paul Jameson to Sarai and Lara in the office, to Wanderson and his installation team led by Paulo, ALL were professional, knowledgeable, super polite, and patient - exemplars of what customer service used to be.  I am very, very happy with my whole house heat pump and additional duct work that was extended into a recent addition.  An added bonus is that they will help with the submission of paperwork for the Mass Save rebate.  For family and friends contemplating similar work in their homes, I'll definitely point them SumZero's way.  Well done!
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Rick Tagliaferri

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