We spend a surprising amount of time on service calls explaining to people what is in their own basement. That is not a criticism of homeowners — it is a consequence of buying a house with a system that predates you, and being handed no documentation at all.
Pennsylvania makes this more common than most states. A great deal of the housing here was built before the Second World War, and an unusual share of it still runs on something close to its original heating design.
The quickest way to tell
Forget the equipment for a moment and look at how heat enters your rooms.
Radiators, or metal fin baseboard along the skirting boards. You have a boiler. It heats water, and that water circulates through the radiators, giving up its heat as it goes.
Vents or grilles in the floor, wall or ceiling, blowing warm air. You have a furnace. It heats air directly and a blower pushes it through ducts.
That distinction matters more than the fuel. A gas boiler and an oil boiler have far more in common with each other than a gas boiler has with a gas furnace.
If you have a boiler, which kind?
Two sorts turn up in Pennsylvania houses, and they behave differently.
Hot water, also called hydronic
Water is heated and pumped around a loop by a circulator. The system is pressurised — a residential one typically sits around 12 psi when cold — and there is an expansion tank to absorb the extra volume as the water heats.
Tells: a small pump-shaped device on the pipework near the boiler, a pressure gauge reading in the low teens, and often several zone valves if different parts of the house are controlled separately.
Steam
Less common, older, and genuinely different. The boiler makes steam, which rises through the pipes under very low pressure, gives up its heat in the radiators, condenses back to water and returns by gravity. There is no circulator pump.
Tells: a sight glass showing the water level in the boiler, a low-water cutoff device, bulky cast iron radiators with a small vent on the side, and a pressure gauge reading in single digits. Steam systems hiss and occasionally knock. Both are information rather than necessarily faults.
Steam systems depend on things that sound trivial and are not: pipes pitched correctly so condensate drains back, and air vents that open to let air out and close when steam arrives. Most “my steam system is terrible” complaints trace to failed vents or pipes that lost their pitch during some earlier renovation.
Should an old system be replaced?
This is where we disagree with a fair amount of the industry.
A cast iron boiler is a remarkably durable object. We work on plenty that are sixty, seventy, occasionally eighty years old and heating their houses competently. The cast iron block itself has no moving parts and corrodes slowly when the system is kept full and reasonably well maintained. The radiators essentially never need replacing.
What fails on these systems is the peripheral equipment — circulator pumps, zone valves, aquastats, expansion tanks, air vents, the burner assembly. All of those are replaceable parts, and replacing them is ordinary repair work rather than a sign the system is finished.
The honest reasons to replace a boiler are narrower than you might be told:
- The block is cracked, leaking or weeping at the seams between sections.
- Several different major components have failed in a short span.
- It is so oversized for the house that it can never run efficiently — common where a house has since been insulated.
- Fuel costs make the efficiency gap worth closing, and you intend to stay long enough to see it.
“It is old” is not on that list. If someone condemns a working boiler on age alone, get a second opinion.
The retrofit problem
Here is the situation we see most in Pennsylvania, and it causes a lot of quiet frustration.
A house was built around radiators. Decades later, the owners wanted air conditioning, so a forced-air system was added — ducts threaded through closets, dropped ceilings and whatever wall cavities could be found. Sometimes the boiler was removed and heating moved to the new ducts. Sometimes both systems remain.
These retrofits are frequently compromised by the route the ducts had to take: long runs, tight turns, undersized trunks and, most often, a return side that was never big enough. The result is a house where some rooms never get comfortable and the equipment is blamed.
Often the equipment is fine. If you have a retrofit duct system in an older house and a room you have given up on, it is worth having the ducts looked at before anything else.
What this means when you call us
You do not need to know any of this to get help — sorting it out is our job, and heating repair covers whatever you have. But two sentences on the phone genuinely speed things up: whether you have radiators or air vents, and whether you burn gas, oil, propane or electricity.
If you are not sure, say so. We would much rather you called and described what you can see than put it off because you felt you should know more about your own basement.