Licensed Maryland HVACR contractor · 41 years in Montgomery County 24/7 emergency service
Poteete HVAC · since 1985

Maryland · Cooling

Central Air Conditioning System Installation in Maryland

Whole-house central air for homes that have never had it, including the duct design work that decides whether the second floor is actually comfortable.

Adding central air to a house that was built without it is a duct design project with an air conditioner attached. Maryland is full of homes — 1920s Takoma Park bungalows, 1940s Silver Spring capes, 1950s Bethesda colonials — that were heated by radiators and cooled by window units for their first fifty years. Dropping a condenser in the side yard is the easy part. Getting conditioned air to the back bedroom on the second floor at 4pm in July is the engineering.

We design the distribution system first: supply trunk routing, register placement, and above all the return path, which is where retrofit systems are most often starved. Then we choose equipment that matches the duct system we can actually build in your house, whether that is conventional sheet metal in a soffit chase, small-diameter high-velocity tubing through existing wall cavities, or a hybrid with ductless heads on the rooms the ductwork cannot reach.

Where we work
Trunk and branch duct system A supply plenum feeding a tapered trunk with branch runs to registers, alongside an undersized single return, with static pressure measurement points marked. Air handler Supply pressure Return pressure Tapered trunk Branch runs to registers Return
Total external static pressure is the sum of both readings, and it is the single most revealing number in a duct system. Above roughly 0.8 in. w.c., new equipment will run hard and die young — which is why we measure before quoting rather than after installing.

Scope

What the job actually includes

  • Whole-house Manual J load calculation plus Manual D duct design
  • Supply and return routing plan drawn before any drywall is opened
  • Air handler placement in attic, basement or closet with proper platform, pan and safety switch
  • Insulated supply trunk and branch runs, sealed with mastic rather than tape alone
  • Dedicated returns — the single most-skipped element in retrofit central air
  • Condensate management with primary and secondary protection above finished space
  • Balancing at the registers and a documented commissioning report

Maryland specifics

Code, permits and rebates

New duct systems in Maryland fall under the 2021 IECC as adopted statewide, which sets duct insulation minimums and duct leakage limits — ducts outside the conditioned envelope, such as in a vented attic, are held to a tighter standard and generally require a duct leakage test. Montgomery County DPS reviews mechanical permits for new duct systems, and in Takoma Park and other local historic districts, exterior condenser placement can additionally require review by the local historic preservation commission. We handle both filings.

Licensing

MD HVACR Contractor License #01-XXXXX. All refrigerant handling is performed by EPA Section 608 certified technicians, and equipment replacement is permitted and inspected through the county.

Process

How we run a central air installation job

  1. Whole-house assessment

    We walk the attic, basement, chases and closets, and identify where a trunk line can physically run. In a 1926 Takoma Park foursquare that may mean a former laundry chute; in a 1955 Wheaton-adjacent rambler it is usually a basement joist bay run.

  2. Manual J and Manual D design

    Load per room drives cfm per room, which drives duct sizing. This is the step that separates a retrofit that works from one where the front rooms freeze and the back bedroom never drops below 80.

  3. Distribution method decision

    Conventional ducted, high-velocity small-duct, ductless, or a hybrid. Plaster walls, no soffit tolerance and a historic district review in Takoma Park or Kenwood often point to high-velocity or ductless; open basements and unfinished attics favor conventional sheet metal.

  4. Installation and drywall coordination

    We sequence with your carpenter or painter where chases are being built, and we protect finished floors and plaster on every entry point. Older plaster does not forgive careless work.

  5. Balance and verify

    Airflow measured at each register against the design cfm, dampers set, and a room-by-room temperature check on a hot afternoon rather than a mild morning.

Pricing

What moves the price

We do not publish a single number, because a number without your house attached to it is marketing rather than information. These are the variables that actually decide what a job costs, and we itemise all of them in writing before any work begins.

How much ductwork has to be built

A house with an unfinished basement and a walk-up attic gives us easy routing. A finished-on-every-level 1930s home with plaster walls and no chases is a different scope entirely, and we will say so before you sign anything.

Distribution technology

High-velocity small-duct systems thread through existing cavities without gutting walls, which preserves plaster and trim in historic homes, but the equipment and labor cost more per ton than conventional sheet metal.

Number of zones

Two-story homes almost always need two zones or two systems. A single system with one thermostat downstairs is the most common reason a retrofit disappoints its owner.

Questions

Central Air Conditioning System Installation questions

Can central air be added to a house with radiators and no ductwork?
Yes, and it is one of the most common projects we do in Silver Spring, Takoma Park and older Bethesda. The hot-water or steam heating stays exactly as it is, and we add a separate cooling-only system — conventional ducted if there is routing space, high-velocity or ductless if there is not.
Will I lose closet space?
Usually some. A conventional retrofit typically needs one vertical chase per floor, often taken from the back corner of a closet or a stair bulkhead. High-velocity systems use two-inch flexible tubing and can frequently avoid chases entirely, which is why they are popular in homes with plaster and original trim worth protecting.
Why is my upstairs always hotter than downstairs?
Heat rises, attics reach 130 degrees in July, and a single-zone system controlled from a first-floor thermostat has no way to know. The fixes are zoning with motorized dampers, a dedicated second system, better attic insulation and sealing, or ductless heads upstairs. We measure before recommending which.
How long does a full central air retrofit take?
Typically three to seven working days depending on how much duct has to be built. High-velocity retrofits in occupied homes usually land in the middle of that range. We stage the work so the house stays livable throughout.

Talk to a technician

Tell us what the house is doing.

Describe the problem and we will tell you what it usually means, what it typically costs to diagnose, and when we can be there. No obligation, no scripted sales call.

Call (301) 555-0182 Request a quote

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