An HVAC system that’s too small for the home will cost you comfort and money. In Staten Island and South Brooklyn, where homes often have additions, enclosed porches or finished attics, many systems no longer match the size or layout of the house. That mismatch leads to poor performance, constant cycling and high utility bills.

If you’re buying or maintaining a home, here’s how to tell when the system is simply too small for the job.

Clear Signs an HVAC System Is Undersized

• The system runs nonstop and still struggles to hit the thermostat setting.

• Certain rooms are always hotter or colder than others.

• Air coming from vents feels weak or minimal, even with clean filters.

• Temps rise quickly on hot days, especially in upper floors.

• The unit is loud, overworked or short cycles repeatedly.

• Humidity remains high indoors even when the AC is on.

Why It’s Common in Staten Island and Brooklyn

Many homes in 103xx and 11209 / 11214 / 11228 have been modified over decades without updating HVAC capacity. Finished basements, attic conversions and rear extensions often add square footage beyond what the original system was designed to support. Older ductwork can also restrict airflow, making the unit feel smaller than its rated output.

How to Diagnose the Problem

• Check the system’s tonnage against the home’s approximate square footage and layout.

• Evaluate whether additions or converted spaces connected to the ductwork.

• Inspect duct size and design; undersized ducts mimic the symptoms of an undersized system.

• Ask an HVAC tech for a Manual J or load calculation to verify proper sizing.

If the system is too small, you may need a higher-capacity unit, a duct redesign or supplemental mini-splits for problem rooms.

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Joseph Ranola | Five-Star Staten Island & South Brooklyn Realtor® (30 + Google reviews)
Associate Broker · Matias Real Estate | Founder · Bridge & Boro Team
Serving 103xx and 11209 / 11214 / 11228 | $25 M + closed volume
📞 917-716-1496 | ranolarealestate.com