It's a more common question than you'd expect, especially for anyone who's moved into an older home without a clear explanation of what heating system it has. Boilers and furnaces both heat a home, but they work in fundamentally different ways, and knowing which one you have changes both what a problem looks like and what actually fixes it.
How A Furnace Works
A furnace heats air directly and pushes it through ductwork to vents throughout the house. It's the more common system in newer construction, and if your home has visible vents in the floor, wall, or ceiling along with a central thermostat, you almost certainly have a furnace. Furnace problems typically show up as a lack of airflow, a system that runs constantly without reaching the set temperature, or uneven heating between rooms served by the same duct system.
How A Boiler Works
A boiler heats water or produces steam, then circulates that heated water or steam through pipes to radiators, baseboard units, or in-floor radiant tubing throughout the house. There's no ductwork involved at all. If your home has radiators, visible baseboard heating units, or noticeably warm floors with no vents anywhere, you have a boiler system. Boiler problems tend to show up differently than furnace problems: lost pressure, cold spots at specific radiators while others work fine, or unusual noises from air trapped in the lines.
Quick Ways To Tell Which You Have
Look For Radiators Or Baseboard Units
Visible radiators or baseboard heating strips mean you have a boiler, not a furnace.
Check For Floor Or Wall Vents
Ductwork vents throughout the house mean you have a furnace.
Listen For The System Running
A furnace produces a rush of moving air. A boiler is quieter, sometimes with a faint gurgle or tick as water circulates.
Check The Main Unit Itself
A furnace is typically a large metal box with visible ductwork connections. A boiler often looks more like a compact tank with pipes running to and from it.
Why This Distinction Actually Matters For Repairs
The two systems fail in different ways and need different diagnostic approaches entirely. A furnace issue often traces back to airflow, a clogged filter, a failed blower motor, or a duct problem. A boiler issue is more often about water pressure, a failed circulator pump, or air trapped in the system, none of which have an equivalent in a furnace system at all. Calling a technician who assumes you have one system when you actually have the other wastes real time during the diagnostic process.
One symptom worth flagging specifically: if your boiler is losing pressure over time, that generally means there's a leak somewhere in the system, even if you can't see standing water anywhere obvious. A proper leak detection assessment can trace exactly where a boiler system is losing water, whether that's at a fitting, the expansion tank, or the boiler itself, rather than guessing and repeatedly refilling a system that keeps losing pressure.
A Note On Older Homes In This Area
Boiler systems are less common in newer Kent-area construction, which has largely shifted toward forced-air furnace systems, but they're still genuinely present in a real number of older homes, particularly on the valley floor where radiant or radiator heat was original equipment. If you've bought an older home in this area and you're not sure what you inherited, it's worth having the system identified and assessed early, ideally before heating season starts, rather than discovering which system you have during the season's first cold snap.
Maintenance Looks Different Between The Two Systems
A furnace system's main maintenance item is the air filter, which needs regular replacement to keep airflow and efficiency where they should be, along with an annual check of the blower motor and ignition components. A boiler system's maintenance list looks different entirely: checking system pressure, bleeding air from radiators, inspecting the circulator pump, and flushing sediment from the system before it accumulates enough to affect efficiency or cause noise.
Because the maintenance itself is so different, it's worth confirming that whoever services your heating system actually has real experience with the specific type you have. A technician who mostly works on furnaces isn't necessarily wrong for a boiler call, but the diagnostic approach and the specific parts involved are different enough that direct boiler experience matters for getting the right fix the first time.