Call: 301-384-1789

About ESI Inc.

Energy Systems, Inc. (ESI) has been serving heating, ventilation, and air-conditioning (HVAC) customers in Maryland and Washington DC for more than 35 years. It is a family-run business headquartered in Lothian, MD, and serving the Metro DC area. We can handle almost any size job, offering professional services with personal attention to both residential and commercial clients. Our goal is to provide the highest quality services, together with quick response at competitive rates.

Our capabilities include service and installation on all types of HVAC systems — we represent and/or have access to all major manufacturers. Our vehicles are fully equipped, well stocked and fitted with state of the art communications for fast response to your needs.

Quality & Reliability

  • We are licensed, bonded, insured, and carry full Workman's Compensation insurance for your protection.
  • Our technicians are CFC refrigerant-recovery certified as required by EPA.
  • Our staff engage in continuing education on current HVAC technologies.
  • We have an excellent local reputation and have received high ratings from Angie's List and Washington Checkbook.
  • We are members in good standing of Steamfitters Local 602, Contractors and Mechanical Contractors, D. C. Association (MCDCA), Metronet, and the Better Business Bureau.


Business hours are 7:00 am to 3:30 pm Monday through Friday. Office hours are 7 am to 4 pm. We also provide 24 hour Emergency Service. (Call our regular number above and our answering service will take your information 24-7 and we will get back to you quickly.)


  • Heating and Cooling
  • Sales and Advice
  • Installation and Retrofit
  • Repair & Replacement
  • Residential and commercial
  • Preventative Maintenance
  • Air Conditioning
  • Heat Pumps
  • Furnaces & Electric Heat
  • High-Velocity (Ductless) AC & Heating
  • Ventilation and AIr Quality
  • Hydronic and Radiant Heating
  • Free Estimates