Mini-Splits for Additions & Older Homes

A ductless mini-split heats and cools a specific space, an addition, sunroom, attic, or older home with no ducts, without the cost and disruption of extending ductwork. It is often the cleanest solution for rooms the main system cannot reach.

These systems connect a small outdoor unit to one or more indoor heads through a slim refrigerant line that needs only a three-inch hole through the wall. There is no need to open ceilings or floors to run bulky ducts. For homes that were never designed for central air, or spaces added long after the HVAC was sized, a mini-split delivers real comfort to exactly the rooms that need it.

Additions, sunrooms, finished attics, and converted garages are notorious for being too hot in summer and too cold in winter. The usual reason is that they were tied into a central system that was never sized to handle the extra square footage, so airflow runs out before it reaches them.

Sunrooms add another challenge, with lots of glass that gains heat fast in summer and loses it fast in winter. Stretching ducts to these spaces is often impractical or wildly expensive, and even when possible it can rob the rest of the house of airflow. A dedicated mini-split sidesteps all of that by giving the problem room its own independent, right-sized system.

Many older Greater Baltimore homes, especially rowhomes and pre-war houses, simply have no ductwork because they were built for radiators or never had central air. Retrofitting ducts into solid plaster walls and tight framing is invasive, messy, and costly.

Mini-splits make whole-home comfort possible in these houses without gutting them. A multi-zone system can serve several rooms from one outdoor unit, each zone with its own control, so bedrooms, living areas, and that always-uncomfortable back room each get the temperature they need. Because most mini-splits are heat pumps, they handle both the humid summer and the cold winter, giving an old home modern, efficient, year-round comfort it never had.

In Greater Baltimore we install a lot of mini-splits in exactly these situations, the back addition that is always freezing, the finished basement that stays muggy, the third-floor bedroom that bakes in July, and the charming old rowhome with no place for ducts.

We often find that one or two well-placed indoor heads solve a comfort complaint a homeowner has lived with for years. For sunrooms, we size carefully for all that glass and Baltimore's humidity so the space is usable in every season. We also pair mini-splits with existing central systems when only part of a home needs help, matching the fix to the house rather than forcing one approach.

If you have a room that the main system just cannot satisfy, a mini-split is worth exploring, and qualifying heat pump systems may be eligible for Maryland EmPOWER utility rebates through BGE. Ask us to check current eligibility, since amounts change. (The federal 25C tax credit ended December 31, 2025 - verified July 2026.) Costs depend on zones and layout, so we will assess before quoting.

Comfort Systems, Inc. has retrofitted ductless comfort into Greater Baltimore additions and older homes since 1995. We are fully licensed and insured under Maryland Master HVAC License #17072 and an Amana dealer. Every home is different, so for an exact quote, call (410) 529-1879.