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Furnaces in Lawrence County sit idle most of the summer, then start running again in October. The first cold stretch is when a weak igniter or a tired blower motor finally gives out, because that's the first real load it's seen in months.
Heat stays on here from October through May. A furnace that's limping along in October will be running that way for most of the year, so it's worth finding out what's actually wrong instead of waiting to see if it gets better.
NOAA nClimDiv, 1991–2020 normals
Eight months of heat and 22 degree nights are normal for a furnace here.
So when one stops working right, the cause is usually a known part, not the weather.
A furnace that won't light or won't stay lit is usually down to one part. The igniter cracks. The flame sensor gets a coat of residue. The pressure switch sticks. None of that has anything to do with New Castle winters being harder on a furnace than anywhere else nearby. It's a part reaching the end of its life after another full season of running. Natural gas ran $13.12 per million Btu in Pennsylvania in 2024, so a furnace cycling more than it should to make up for a bad part is worth fixing for that reason alone. A contractor can usually tell which part it is by how the furnace is failing. No ignition at all, ignition that won't hold, and short cycling each point to a different place to look.
If your furnace came with a house built around 1957 or earlier, ask whether it's worth repairing before you pay for the repair. A contractor can tell you what's actually wrong, and whether it has real life left or is close to the end.
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Most furnace failures trace back to wear on one part, not a sudden breakdown. The igniter is usually first. It heats up to light the burners every single cycle, and that repeated heating and cooling eventually cracks it. A flame sensor works nearly as hard, sitting right in the burner flame, and over time it picks up a film that keeps it from sensing the fire at all, so the furnace shuts itself off as a safety measure. Blower motor bearings wear down from spinning for the length of every heat cycle, and a motor on its way out will usually get louder or slower before it quits outright. Pressure switches and draft inducers fail less often but still have moving parts that stick or wear. None of this is random. It is what happens to the same parts, doing the same job, cycle after cycle, for as long as the furnace is asked to run.
Make sure the thermostat is set to heat and set a few degrees above room temperature, and check that its batteries aren't dead. Then find the furnace switch, it looks like a light switch on or near the unit, and make sure nobody bumped it off. Check the breaker too. None of that takes a tech to rule out.
Pull the filter and hold it up to a light. If you can't see light through it, it's choking off airflow and the furnace is working harder than it should. Walk the house and make sure no vents are closed or blocked by furniture. A furnace starving for air can overheat and shut itself off as a safety measure, which can look like a bigger problem than it is.
Estimates for a typical Lawrence County home, compared with an older unit built to the previous federal minimum, from EIA household energy data, Pennsylvania fuel prices and NOAA climate normals. Your home will differ.
Repair makes sense when one part has failed and the heat exchanger is sound.
Replacement makes sense when the heat exchanger is cracked or the furnace keeps needing parts.
Once the easy checks are out of the way, a diagnostic visit starts with watching the furnace try to run. A tech wants to see the actual failure, not just hear about it. So the first step is usually setting the thermostat up and watching what happens from a cold start. Does it try to ignite and fail. Does it light and then drop out. Does it run a short cycle and shut off. That sequence narrows things down fast. From there it's testing with meters, not guessing. Checking voltage at the igniter. Reading the flame sensor's signal. Watching the pressure switch as the inducer spins up. Each part has a range it should read in, and a part outside that range is the answer. The furnace gets opened up, not just looked at.
