In Greater Cincinnati the heating season runs roughly from October to April. All summer your furnace sits idle, and then one cold night everyone in town turns the heat on at once. That first cold snap is when weak parts show themselves, and it is also when every heating contractor's phone is ringing.
A fall checkup moves that discovery to a mild afternoon instead of a cold night.
Why fall service matters
A furnace follows a fixed startup sequence. The thermostat calls for heat. The inducer motor starts and clears the heat exchanger. A pressure switch proves the venting is open. The igniter heats up or sparks, the gas valve opens, the burners light, and a flame sensor confirms there is flame. Then the blower comes on and moves air across the heat exchanger. If any one of those steps fails, the furnace locks out.
Several of those parts wear quietly while the furnace sits. Flame sensors build up a coating and stop reading flame reliably. Hot surface igniters develop hairline cracks. Inducer motor bearings dry out. Condensate traps on high-efficiency furnaces collect sludge, and a backed-up trap can trip the pressure switch. A technician can find these before they leave you without heat.
Fall service is also about safety. The heat exchanger is what separates the flame and combustion gases from the air you breathe. A technician inspects it for cracks and corrosion, checks that the flue is drafting properly, and tests for carbon monoxide. A homeowner can't check those things, and they matter more than anything else on the list.
There is an efficiency side too. Clean burners, correct gas pressure and proper airflow across the heat exchanger let the furnace make the heat it was designed to make without running longer than it needs to.
Warning signs to watch for
Any of these is worth a service call, whatever the season:
- The furnace lights, then shuts off after a few seconds. This is often a dirty flame sensor or a grounding problem, and it can repeat until the control board locks out.
- A boom or loud pop at startup. That can mean delayed ignition, where gas builds up before it lights. Have it looked at promptly.
- Short cycling. Running a couple of minutes, shutting off, then starting again points to overheating, an airflow problem or a thermostat issue.
- Cool air on a heat call. Could be an ignition failure, a tripped limit switch or a clogged condensate drain.
- Squealing, grinding or rattling. Usually a motor bearing, a loose blower wheel or a failing inducer.
- Soot, rust or water around the furnace. Signs of venting, combustion or condensate problems.
- Some rooms much colder than others. Often airflow and ductwork rather than the furnace itself.
A dusty burning smell for a few minutes the first time the heat runs each fall is normal. A smell that lingers, or anything that smells electrical, is not. Shut the system off and call.
When it's an emergency
If you smell gas, leave the house and call your gas utility or 911 from outside. Don't flip switches or try to find the leak. If a carbon monoxide alarm sounds, get everyone out and call 911. If you don't have working CO detectors on every level of the home and near the bedrooms, take care of that before the heat comes on this year.
Never open the furnace burner compartment or touch the gas valve. Changing the filter is fine, but shut off power at the furnace switch or breaker first.
The best time to schedule a heating checkup is before you need the heat. Call JM Mechanical at (513) 667-8484 or request service online to get your furnace looked at before the first real cold snap.