Boiler

How hydronic heat works

A boiler burns gas or oil (or uses electricity) to heat water in a sealed vessel. In a hot-water system, a circulator pump pushes that water through piping to radiators or baseboards, where it sheds heat into rooms before returning to be reheated; in an older steam system, the boiler boils water and steam rises through pipes to radiators on its own pressure. Because water carries far more heat than air, hydronic systems deliver even, draft-free warmth without blowers or ductwork. Modern condensing boilers extract extra heat from exhaust gases, reaching efficiencies well above traditional cast-iron models.

Boilers handle heating only. Homes with boilers add cooling separately — most often with ductless mini-splits, since there are no ducts to share.

Living with a boiler in Southeastern Pennsylvania

Rowhomes and prewar houses across Philadelphia and its older suburbs commonly heat with boilers, many of them decades old. Cast-iron boilers are famously long-lived, but age shows up as rust and water on the floor, radiators that stay cold (often just trapped air that bleeding fixes), banging pipes, a pilot or ignition that won't hold, or pressure that keeps drifting. Annual service — checking the relief valve, expansion tank, water pressure, and combustion — keeps a boiler safe and efficient, and matters even more for steam systems with their low-water cutoffs. When an old boiler does fail, replacement is a chance to right-size the new one to the actual radiation in the house. PJ MAC HVAC repairs and services gas and oil boilers throughout the Greater Philadelphia area.