Most Philadelphia rowhomes are heated by a gas boiler that sends steam or hot water to radiators, not by a furnace. A furnace heats air and pushes it through ducts, which older rowhomes were never built to hold. Check your rooms: radiators mean a boiler, floor or wall registers mean a furnace.
Key takeaways
- A boiler heats water or makes steam for radiators; a furnace heats air for ductwork.
- Rowhomes built before central ductwork usually have a boiler, and many still run steam.
- Steam and hot-water boilers need different upkeep, so knowing which one you have matters.
- Switching a rowhome from a boiler to a furnace is a renovation project, not a swap.
- A well-kept boiler can outlast a furnace, so the system you have is often worth keeping.
How do I tell if I have a boiler or a furnace?
Walk through the house and look at how heat gets into each room. Cast-iron radiators, slim baseboard fins along the wall, or a hot floor with no vents all point to a boiler. Metal grilles in the floor, walls, or ceiling that blow warm air point to a furnace.
Then look at the unit itself. A boiler is a compact box with water pipes running in and out, often with a pressure gauge or a glass tube showing a water level. A furnace is a taller cabinet with a large sheet-metal trunk on top that branches into ducts. If there is a central air conditioner, its indoor coil usually sits on top of a furnace, which is another clue.
One more tell: if the basement has a round chimney connector and a pipe that clanks when the heat kicks on, you almost certainly have a steam boiler.
Why do so many Philadelphia rowhomes have boilers?
Most of the rowhomes in Fishtown, Kensington, Port Richmond, and South Philly went up before forced-air heat was common. Builders piped radiators through narrow houses because pipes fit where ducts never could. Early on, those systems burned coal and made steam. Over the decades, they were converted to oil and then to natural gas, but the radiators and much of the piping stayed.
That is why a house from 1915 can still run on one-pipe steam today. Later rowhomes and many updated ones use hot-water boilers instead, which move water through the radiators with a pump. Both are boilers. Both work well when they are maintained. The difference shows up in what they need from you and from us.
Steam or hot water: what does each one need?
A one-pipe steam system sends steam up to each radiator through a single pipe, and the condensed water drains back down the same pipe. It depends on a few simple parts working together.
A hot-water system is a closed loop. A circulator pump pushes heated water out to the radiators and back. Its parts are different, and so are its problems.
- Steam: air vents on each radiator that open to let air out and close when steam arrives.
- Steam: correct pitch on the radiator so water drains back instead of pooling and banging.
- Steam: a low-water cutoff that shuts the burner down if the boiler runs short of water.
- Steam: a sight glass and a pressure gauge that a technician reads at every visit.
- Hot water: a circulator pump and, in some homes, zone valves that send heat to one floor at a time.
- Hot water: an expansion tank that absorbs pressure as water heats, and bleed valves that release trapped air.
What does a forced-air furnace need instead?
A furnace burns gas to heat a metal heat exchanger, and a blower pushes house air across it and out through ducts. You will find these in newer construction, in rowhomes that were gutted and rebuilt, and across most of Lower Bucks County. Its upkeep is different: filters need changing, the blower and ducts need to stay clean, and the heat exchanger needs a yearly look for cracks.
The big advantage of ductwork is that the same ducts can carry central air conditioning in summer. Many suburban homes pair a furnace with an outdoor AC unit or a heat pump for that reason. In a rowhome without ducts, cooling usually comes from ductless mini-splits or window units instead.
Should I switch my rowhome from a boiler to a furnace?
Usually not just for the sake of switching. Running new ductwork through a finished rowhome means opening walls, giving up closet space, and dropping ceilings. If your boiler is in good shape, the smart move is often to keep it, tune it every fall, and fix radiator problems as they come up. A boiler that gets that care can run for decades.
Switching starts to make sense during a full renovation, when the walls are already open, or when a boiler has reached the end of its life and you also want central air. Even then, we lay out the options side by side: a new boiler like the one you have, a high-efficiency boiler, or a furnace and duct system. What drives the estimate is the venting path, the chimney liner condition, the duct routes, and Philadelphia L&I permit requirements, which you should confirm at the time of the work.
Not sure what you have or where it stands? Request a heating inspection and we will walk the system with you and give you options before any work starts.
People also ask
Can I add central air to a rowhome with a boiler?
Is a boiler less efficient than a furnace?
What is a heat pump, and does it work in a rowhome?
Do I need a chimney liner when I replace a boiler?
References: U.S. Department of Energy. Requirements vary by municipality and change over time; confirm current rules with the authority having jurisdiction.