The core difference
A boiler heats water and distributes heat through radiators or radiant loops; a furnace heats air and blows it through ducts. NYC's older building stock is heavily boiler-and-radiator, which is why boilers dominate here.
Why NYC leans toward boilers
Most pre-war and many newer NYC buildings were built around steam or hydronic distribution — radiators, not ductwork. Converting to ducted forced-air is usually impractical, so boilers (or ductless heat pumps) are the realistic heat options.
When a furnace or heat pump fits
Furnaces make sense where ductwork already exists; increasingly, ductless heat pumps are the modern alternative for buildings without ducts, offering heating and cooling in one system.
Bottom line
In most NYC buildings the question is really "repair/replace the boiler, or go ductless heat pump?" — not boiler vs furnace. We'll assess your distribution and give a straight recommendation.
