Is this your business?Claim this page →
Verified record
Nelson Mechanical Design does plumbing and HVAC work; the company says it handles new installations, repairs and maintenance for plumbing, mini-split systems, geothermal systems and water treatment. A local paper has described it as offering an eco-friendly alternative to fossil fuel HVAC and plumbing systems. Its Massachusetts HVAC licence, number 730-SM-B, is active on the state registry under Nelson Mechanical Design, Inc. On Google it holds 3.9 stars from 30 ratings. A recent customer wrote that after the reviewer's mother's AC went out, another company quoted over $21,000 for a new heating and cooling system, and a second opinion from Nelson showed the problem was a $150 part. In a recent review, a customer said Nick Rivers made careful adjustments to a heat pump on the weekend before a birthday party. A 2025 customer with a 27-year-old boiler said the company obtained the needed part and installed it 5 days ahead of the anticipated install date. A 2025 customer said that within 10 minutes of a technician's visit the problem was diagnosed and parts were ordered. A 2024 customer said that when parts for a failed boiler were hard to source, the company completed a new installation in a couple of days. A 2023 customer wrote that when a water heater burst, they arrived in less than half an hour and stayed late into the night. A 2022 customer said the final invoice for a central air-conditioning replacement came in below the original estimate. A 2021 customer described converting from oil to electric heat with a minisplit system through the Massachusetts HEAT Loan program, with Nick guiding the process from start to finish. A recent customer in elderly housing, where mini-splits were being installed, said the reviewer was treated with disrespect and the apartment was left in disarray. A recent customer whose heat and AC system was installed in 2024 described a burst pipe and flood that caused extensive damage, said the company ultimately admitted fault after first denying it, and described long delays in responding to later issues. A 2025 customer described terrible communication over a couple of years and said Brian Nelson sent a rude email rather than calling.
“You could try Brennan & Co or Nelson Mechanical.”
“HVAC technicians in Mitsubishi-branded sweatshirts gathered recently for class at Nelson’s Mechanical Design headquarters.”
“Nelson Mechanical Design offers an eco-friendly alternative to fossil fuel HVAC and plumbing systems.”
I am writing to strongly recommend Nelson Mechanical Design, and perhaps give a cautionary tale for others who blindly trust what their HVAC company tells them without getting a second opinion from NMD. We just saved over $20,000 thanks to the keen attention to detail, expertise and knowledge of NMD service manager, Declan McCarthy. My elderly mother's AC went out suddenly in July. We called our company, "B" (used to be island owned but unbeknownst to us and no doubt many others was sold a few years back and is no longer a vineyard company, but is in fact part of a large corporate outfit based in Georgia). This (off island) company spent maybe one hour doing a cursory diagnostic test. We then received a quote for over $21,000 (plus 'optional' add-ons -- not including any electric, carpentry, or plumbing that might be needed) for a brand new heating and cooling system to replace this supposedly broken and obsolete system. I decided to get a second opinion with NMD. It turns out that the other company's technician did not even cover the absolute minimum of what Declan said would be NMD's basic common diagnostic practice. My mother is 84 years old and If she had been managing the house on her own, she would now be replacing her entire system for what turned out to be a $150 part. The quote from "Company B" was absolutely predatory. I am happy to say that we are now using NMD exclusively after dodging a 20,000+ bullet. I do not hesitate to write this review to go with Nelson Mechanical Design, an honest island company who isn't just out to give a falsified and inflated quote to procure islanders' business. Declan McCarthy, you are our hero! Thank you also to the savvy technicians and to NMD for their knowledge and honest business practices.
I live in elderly housing on Martha Vineyard. We’re in the process of having mini Splits installed in our apartments. Myself being handicapped and wheelchair bound, I’ve been treated with disrespect. They left my apartment today in disarray and I do not recommend them for anything!
If there were ten stars, I would have given it. We had a mess on our hands, and Nelson made things perfect. They did EXACTLY what they promised, and more, at the price we agreed to .Rarely have I encountered a more thorough, responsive and professional company. I can't recommend them enough.
Had a fantastic experience with NMD. Nick Rivers came out and made careful adjustments to my heat pump on the weekend right before my birthday party. They were prompt, responsive, and respectful. Highly recommend!
Nothing but problems since new system for heat and a/c installed 2024. First a burst pipe and flood, causing extensive damage to our home. Cleary related, and the ultimately admitted fault --but denial was the first protracted response. With subsequent issues, blame shifting, long delays in responding, terrible attitude. Deplorable customer service. Avoid!!
Specializes in
Also offers
Languages
1 change recorded — last scanned Oct 29, 2026.
Typical Greater Boston range for this kind of work, from regional averages — not a quote from Nelson Mechanical Design. Use it to sanity-check bids, then get the real number in writing.
Estimated range
$5,000 – $11,400
Typical HVAC project around $8,200
Transparent diagnostics5.0
Same-day and weekend calls for burst pipes and lost heat5.0
Broad plumbing and HVAC range5.0
Repeat, years-long customers5.0
Water heater and boiler installs5.0
Heat and AC calls answered within a day3.4
