McDonnell Mechanical Services

We hired McDonnell to install a new HVAC system in our house in July 2026-- ductless mini-splits downstairs and a fully ducted system in the 2nd floor. McDonnell wasn't the lowest price quote, but we chose them because of the strong positive references we received from other customers in our area. Compared to the competitors, McDonnell gave us the most thorough and detailed proposal. They were extremely helpful and patient during the design & quote process. And once we engaged them, their installers were incredibly professional, and took a lot of care to not disrupt the rest of the house as much as possible. They installed the system on time per their promised schedule, and everything worked perfectly, exactly as promised. Whenever I had a question, both during and after installation, they were incredibly responsive and promptly answered all of my questions. I would definitely work with them again in the future, and I would highly recommend them to others.

McDonnell Mechanical Services from Dennis Ma, removed and replaced a boiler and hot water heater including all related plumbing, bleeding of all baseboard and stand up heaters, top and bottom floors, in an older Chatham Ma home. There was a handful of people who delivered materials and removed the old equipment, all of which went smoothly and on time. However, we wanted to give a shout out to both the company and the the plumber and apprentice who did the majority of the work. David was not only completely knowledgeable about the whole project from beginning to end, he was also an incredible teacher/instructor to the female apprentice, Dakota, who is working toward her journeyman license. As a retired State of Connecticut maintenance carpenter who worked in Ct DCF facilities for 26 years. I've seen a lot of different contractors. I have to give an A+ to both David and Dakota for their knowledge, professionalism, work ethic! Great to see women in the trades!

Needed furnace replacement at my house in Chatham. Got quotes from a number of local providers. Decided to go with McDonnell. Their price was in-line those received with by others. But their reliable communication, help in identifying/explaining options, and reliability made the difference. The final cost and project timeline ended up being exactly what we had agreed on. Now will use McDonnell for my annual ac service as well.

Used McDonnell to install new heating system for my house on the cape and for annual heating & ac tune ups. Great people. The founder Jim McDonnell even will take the time to answer any questions i have with my systems.

McDonnell Mechanical installed a new ductless system in our condo. From the start they listened to our needs (and HOA requirements) and provided us with a great system. Most companies can do that, but they showed their 5-star qualities when we had manufacturer issues with some of the equipment. McDonnell pushed back on the manufacturer, resolved the issue in a timely manner, and kept us informed all along the way.