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about us

Ralph P. Sita, Inc. is a locally owned and operated, full service, residential, industrial, and commercial heating, ventilation, and air conditioning contractor with over 42 years of experience in the industry. 


Located in Dunkirk, Maryland, we serve the District of Columbia, Virginia areas, as well as local Maryland Counties, including but not limited to: Calvert, Charles, St. Mary's, Anne Arundel, Prince George's, Howard, Montgomery, and Queen Anne's. 

Ralph P. Sita, Inc. is a union contractor with personnel trained and supplied by the Steamfitters Local Union #602. Our mechanics have years of experience and are equipped with the most up to date training and tools of the trade. We design, install, and service pneumatic controls, mechanical equipment, heating, air conditioning and ventilation systems, and offer full service, commercial and residential, preventative maintenance service contracts. 

Ralph P. Sita, Inc. is fully licensed and insured in Maryland, Virginia, and the District of Columbia.


Ralph P. Sita, Inc. is also an accredited business with the Better Business Bureau (BBB).


Frequently asked questions

  • How often should my HVAC be serviced?
    Have your system inspected by a professional HVAC contractor in the spring and fall to coincide with the cooling and heating seasons. This will ensure everything from the blower (the internal motor) to the thermostat is running smoothly and your house will stay warm and cool when you want it to.
  • How often should HVAC filters be replaced?
    Change your filter every three months (each season) for 1-inch filters, or more frequently if you have pets, smoke or allergens in the house, all of which make filters work harder. Each house or unit has a different filter size (some have more than one filter), so check the filter size(s) before you purchase. Energy Star reports that changing the filter is a top DIY action item for a properly functioning HVAC system, as “a dirty filter can increase energy costs and damage your equipment, leading to early failure.”** And just think, each time you replace the filter you are helping to improve the air quality in the house.
  • Why should I perform preventive maintenance?
    Heating and cooling systems work incredibly hard to perform their functions for your household. The constant stopping, starting and continual operation can wear down a machine quickly and unexpectedly if the proper care and maintenance is delayed. However, by performing preventive maintenance, or servicing your system regularly, you can maximize the life-cycle of your heating or cooling unit and guard against many unexpected failures. Preventive maintenance inspections performed on a regular basis can uncover leaks, rust, rot, soot, frayed wires and corroded electrical contacts.
  • What equipment requires preventive maintenance?
    At least once a year, we suggest that homeowners schedule a professional tune-up for the central heating and cooling system in their home. Inspections on boiler and furnace systems should include duct work, pipes, dampers, valves, the chimney, registers, radiators, pumps, blowers, fuel lines, the gas meter, oil tank and every part of the actual furnace and boiler. Meanwhile, heat pump and air conditioning unit inspections should also include inspections of the fan, compressor, indoor coils, outdoor coils and refrigerant lines.
  • Which HVAC system is right for me?
    Schedule an appointment with us. We’ll come to your home and evaluate its size, heating and cooling needs, environment, and the work we’ll need to do. Then, we can recommend the best system for you and install it quickly.
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