Welcome to McDonnell Mechanical Services

McDonnell Mechanical Services (MMS) is a customer-focused heating, air-conditioning, ventilation and generator company located in West Dennis, MA. We are State licensed (oil & gas) and fully insured serving the commercial and residential market of Cape Cod at a fair cost.

McDonnell Mechanical Services technicians are fully certified and factory trained. Our staff keeps up with the latest building code changes, and we will identify and obtain the necessary permits for all installations. We will arrange all needed inspections by fire or gas inspectors. As wonderful as all this HVAC equipment is; it will not function during a power outage. Standby generator backup for mechanical systems makes a lot of sense as part of a comprehensive package of environmental conditioning.

Contact Information:
Phone: 508-394-0005
Toll Free: 855-442-1914
[email protected]
You can count on McDonnell Mechanical Services.

  • 24 Hour emergency service
  • Service and repair of oil & gas heating systems
  • Preventative maintenance and annual service contracts
  • Replacement or retrofit of existing equipment, controls, piping and ductwork
  • Upgrade existing system for comfort and/or efficiency
  • Design and permitting of  HVAC systems and Generator equipment
  • Installation, startup and balancing of new equipment
  • Mitsubishi Diamond Dealer
  • Established Generac Dealer