From boilers and furnaces, to pipe, duct work, and fittings, Capitol District Supply is your best bet for heating and air conditioning equipment and supplies. We’re proud to be a major representative for IBC, ‘Better Boilers’, as well as stocking everything for most HVAC systems, and are known as Radiant Heating Specialists!

Heating & Air Conditioning

Boilers: Pennco, Navien, IBC, Crown, Velocity

Furnaces: Olsen Gas, Comfort-Aire, Regal Oil, Heil Gas & Oil

Heat Pumps: Mitsubishi Electric

Air Conditioning: Comfort-Aire, Century, Mitsubishi Electric

Radiant In-floor: Zurn, Legend, Ultra-Fin, Comfortpro, Rehau

Space Heaters: Empire Direct and Chimney Vent

Unit Heaters: Oil, Gas, Water, and Steam, Beacon Morris

Baseboard: Embassy

Controls: Honeywell, White Rogers, Watts, Argo, Tekmar, Hydrolevel, Lux, HBX, Bell & Gossett

Circulators: Taco, Grundfos, Bell & Gossett

Power Venters: Field

Zone Dampers: Arzel

Zone Valves: Automag, Honeywell, Taco

Heating Accessories: Hercules Anti-Freeze, GeneralAire, Vive Thermostats, Ultra-Fin, Vent-Rite, DiversiTech, TracPipe and Counter Strike Flexiable Gas Tubing: 1/2″-1″

ConStab Underground Poly Gas Pipe: 3/4″-2″

Acetylene Refills – Saratoga Only

Water Heaters

American: Natural Gas, Electric, Propane

Bock: Oil

IBC: Tankless, Combi and Indirect Tanks

Navien: Tankless, Combi System


Round Pipe & Fitting: 3″ – 24″ insulated flex 5″-18″

Trunk Duct Fittings: 8″ x 8″ to 8″ x 30″

Boots, Takeoffs: etc 5″ – 10″

Oval Pipe & Fittings: 6″, 7″ and 8″

Plenums, Wall Stack, Panning, Rain Caps, Dampers, Ameri-Vent Registers: floor, wall, ceiling, T-Bar, J&J Register

Chimney Pipe (Gas/Oil/Wood)
Air Jet: Gas 4″ – 10″, oil/wood 6″ & 8″,
Aluminum chimney flexliners
Protech stainless steel venting systems




  • Heating and cooling load calculations
  • Radiant loop diagrams using Wrightsoft software systems
  • Visio & Tekmar piping and wiring diagrams

What We Can Do For You

At Capitol District Supply, we work with contractors and homeowners to find the best fit for a property’s heating and air conditioning needs. We always recommend that a qualified contractor install a heating or air conditioning system.

If you want to update and improve your heating or air conditioning system, we recommend letting us calculate a Heat Gain Load (Heat Loss) to determine the best unit for your home. This calculation will take into consideration the size of your home, the number and size of doors and windows (where air escapes), and which direction your house faces (to address how the sun affects the temperature in your home).

5%A Heat Gain Load is done for both new construction and existing homes. In order to complete the calculation for your property, we need:

  1. Sketch of the floor plan for the house (width, length, height dimensions)
  2. Window and exterior door dimensions, type, location, and direction (North, South, etc)
  3. R-Value of insulation in walls, ceilings, floors

Once we complete a Heat Gain Load, we will know the BTUs lost from the home and can match the net output of the furnace or boiler to best fit your home. This will allow you to purchase a unit that will be the best investment for performance and energy usage