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Cooling Guide

How to Add Central Air to a House With Radiators: Ductless, High-Velocity or New Ducts

A definitive comparison of modern air conditioning options for historic stone and radiator-heated homes across Delaware County and the Main Line.
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Published September 30, 2026By Littlejohn Air Pros Technical TeamCooling

To add air conditioning to a radiator-heated home without existing ductwork, homeowners have three proven options: ductless mini-splits (the most cost-effective and least invasive method, using small wall units connected by 3-inch exterior wall penetrations), high-velocity small-duct systems (utilizing flexible 2-inch mini-ducts fished through existing closet walls and floor joists to tiny round ceiling outlets), or installing full sheet-metal ductwork (which requires building drywall soffits and sacrificing closet space). Ductless mini-splits are chosen in over 80% of Delaware County retrofits.

Throughout older Main Line and Delaware County communities like Wayne and Havertown, thousands of magnificent stone homes, brick twins, and Victorians rely on hydronic radiators. While radiators provide superb winter warmth, Pennsylvania summer humidity makes modern air conditioning essential.

Comparing the 3 Retrofit Methods for Radiator Homes

Retrofit Cooling Options for Homes with Radiators
MethodArchitectural DisruptionRelative CostDehumidification & Efficiency
Ductless Mini-SplitsMinimal (3-inch wall core hole)Moderate ($)Best in class; ultra-high SEER2 & independent room zoning
High-Velocity Small Duct (Unico/SpacePak)Low to Moderate (fished through closets)High ($$$)Excellent humidity removal; discrete small round ceiling vents
Traditional Sheet-Metal DuctsSevere (requires dropped ceilings & chases)High ($$$) + CarpentryStandard central air comfort; loses closet square footage

Why Ductless Mini-Splits Dominate the Delaware County Market

Ductless mini-splits preserve historic architectural details. There is no need to destroy lath-and-plaster ceilings, build boxy soffits over antique pocket doors, or give up second-floor closet space. Outdoor heat pump condensers connect to indoor air handlers via flexible line sets concealed in aesthetic paintable covers that match your home’s exterior trim.

Furthermore, because every indoor unit has its own thermostat, you never waste money cooling unoccupied guest rooms or basements. In winter, modern cold-climate heat pumps also provide hyper-efficient supplemental heating down to sub-zero temperatures.

Discreet ductless mini split air handler mounted high on plaster wall of historic Pennsylvania colonial home
Ductless indoor air handlers provide independent zone climate control without cutting into historic plaster or woodwork.

Need emergency heating or AC repair in Broomall?

Dispatchers are on call 24 hours a day to send an insured technician to your home.

How to Plan Your Home’s Retrofit Cooling Project

Before signing an installation agreement, ensure your electrical panel has adequate capacity (100A or 200A service), verify equipment sizing through a room-by-room load calculation, and review local municipal building codes. Explore our complete guide to heat pump and mini-split services or call (321) 478-0693 for an in-home evaluation.

Related HVAC Services

Need professional assistance with the topics discussed in this guide? Our licensed technicians are on call:

Heat pump diagnostics, reversing valve troubleshooting, defrost cycle repairs, and ductless mini-split installation for Broomall homes with radiator heat or hot upstairs rooms.

Learn more

Expert heating and cooling equipment replacements: Manual J load calculations, SEER2 efficiency options, oil-to-gas conversions, chimney liners, and Marple Township code permitting.

Learn more

Specialized hydronic repairs for Broomall and Delaware County homes: steam boilers, hot water baseboards, circulator pumps, zone valves, water hammer diagnosis, and oil burner servicing.

Learn more

Clear Answers

Frequently Asked Questions

Common questions Delaware County and Broomall homeowners ask about repairs, costs, and equipment.

Not at all. Your radiators and boiler remain completely independent. The ductless system handles all summer air conditioning and dehumidification, while offering economical supplemental heat during mild fall and spring weather.

Have an urgent question not answered above? Dispatchers are live 24/7.

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Estimates & Non-Urgent Service

Have a Question About This Topic?

For the fastest help, call (321) 478-0693. Use this form for jobs that can wait a day: a seasonal system replacement consultation, a second opinion on an equipment quote, or a ductless mini-split installation for an addition.

  • We follow up by phone to confirm details and schedule a convenient dispatch window.
  • Immediate heating or cooling breakdowns are handled via our 24/7 telephone dispatch.
  • Every technician is insured and gives you flat-rate pricing before work begins.
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