Prompt professional service and installation in the D.C., Maryland and northern Virginia area.

For 24-hour emergency service call 301-350-5000

For over 80 years, RM Thornton Service has been providing exceptional HVAC and plumbing service and maintenance throughout the Washington metro area to ensure reliable building operations and extend equipment life. We offer 24/7 emergency response and are proud to have some of the most prominent commercial, industrial and institutional organizations as our clients. From basic maintenance to emergency repairs, our certified technicians are ready to tackle your commercial servicing projects.


As a division of Harris Companies, RM Thornton Service is able to draw on the resources and expertise of an extended team of plumbers, pipefitters, electricians, building automation engineers, refrigeration system experts and engineers, and self-perform a large majority the work saving its customers valuable time and money.

Customer Service, Craftsmanship, Integrity, and Experience

From facilities service contracts to the most complicated commercial HVAC installations, repairs and retrofit projects, RM Thornton Service exceeds expectations by every measure.  Our blue chip customers appreciate our legendary customer service and our quality craftsmanship has been recognized by the Washington Building Congress with 14 individual and team Craftsmanship and Star Awards. Watch Harris Companies in 60 Seconds to learn more about how we can help you.