What good is a gas furnace during an Ohio winter if it won’t stay on long enough to heat a house? Not much, and if this is happening in your home, you may need to call our technicians for heating repair in Akron, OH. Although there might be a simple troubleshooting step you can take to solve the problem, anything more advanced must be left to our trained professionals. Amateur work on a gas furnace is potentially dangerous!
Why won’t my gas furnace stay on?
- Dirty air filter: restricts airflow, causing the heat exchanger to overheat and trigger a safety shutdown.
- Miscalibrated thermostat: shuts off the furnace prematurely if it senses higher temperature than actual.
- Flame sensor issues: dirt on the sensor can falsely detect no flame and shut off gas flow.
- Gas flow problems: stuck valves or line blockages can cut off burner supply
- Faulty control board: may turn off burners when the blower kicks in.
- Oversized furnace: heats too quickly, so the thermostat finishes the cycle before the house is warm.
Let’s get down to business and see why your furnace is struggling to stay on…
Lack of airflow is causing it to overheat
One of the first things to check on your furnace is if its filter is dirty and needs to be replaced. Lack of airflow into the furnace can have several detrimental effects, and one of them is causing the heat exchanger (the part of the furnace that does the actual heating of the air) to fail to cool down. If this part overheats, it trips a limit switch that will shut down the furnace. To understand more about why this component is critical, read why a damaged heat exchanger is such a big deal. The heat exchanger can also overheat because of poor ventilation of combustion gases, and this will require professionals to fix it.
The thermostat is miscalibrated
If your furnace stays on for long enough to start to warm the house but shuts down before it reaches your desired comfort level, the issue may be a miscalibrated thermostat. When the thermostat senses the wrong temperature indoors, it will shut off the furnace too early. Professionals can easily recalibrate the thermostat to remedy this. Cold spots in your home may also indicate thermostat or airflow issues.
The flame sensor is dirty
The flame sensor detects if the burners in the furnace have ignited. If the burners fail to ignite, the flame sensor will automatically shut off gas flow to the burners as a safety precaution; this stops unburned gas from flooding the combustion chamber. If the flame sensor becomes dirty, it may start to shut the gas off even if the flames ignite. Technicians can clean the sensor or replace it. You can learn more about this common issue in our article, this sensor could be making your heater appear broken.
Gas flow issues
The burners may not be receiving enough natural gas to continue to burn. This can be due to stuck valves or blockage in the gas lines, or potentially even leaks. As with anything connected to the gas lines, you want professionals only to work on this. Shut off the furnace and call for assistance. In some cases, rare furnace repair issues can be difficult to detect until they cause shutdowns.
Faulty control board
The control board manages the order in which various parts of the furnace turn on and off. A faulty board can result in the burners turning off as soon as the blower fan comes on, as well as many other malfunctions, often requiring uncommon furnace repairs you won’t see coming. The board will need professional repairs or a replacement.
Oversized furnace
Did you just get this furnace before the winter? If so, the trouble may be that whoever installed it failed to properly size it for your home and put in one that’s too powerful. An oversized furnace will so rapidly raise the indoor temperature that the HVAC system will falsely determine it has completed the heating cycle and shut the furnace off. Before installing a new furnace, ensure accurate sizing with tips from our post, how to prepare for furnace installation. The only way to fix this problem is to replace the furnace with one that is accurately sized for your house. You can trust our professionals to see any furnace we install is the right size.
Frequently Asked Questions
Question: What are common reasons my gas furnace shuts off prematurely?
Answer: A gas furnace that won’t stay on can be caused by several issues, including clogged air filters leading to overheating, a miscalibrated thermostat, a dirty flame sensor, insufficient gas flow, a faulty control board, or even an oversized unit triggering false temperature readings.
Question: How does airflow affect the furnace staying on?
Answer: Poor airflow—often from dirty filters, blocked vents, or restricted ductwork—can cause the heat exchanger to overheat. This trips safety switches that shut the furnace off. Cleaning or replacing filters and ensuring vents are unobstructed usually helps.
Question: What role does the flame sensor play in this issue?
Answer: The flame sensor detects burner ignition. If it gets dirty or weakened, it may falsely think the flame is out and shut off the gas flow. Cleaning or replacing this sensor typically solves repeated shutdowns shortly after ignition.
Question: Could the thermostat be to blame for furnace cycling?
Answer: Yes. A thermostat that’s miscalibrated, located in a hot or cold spot, or suffering from low batteries or faulty wiring can signal the furnace to turn off too early. Recalibration, relocating, or replacing the thermostat can resolve the problem.
Question: What does furnace “short cycling” mean and why is it a problem?
Answer: Short cycling occurs when a furnace turns on and off too quickly—typically before reaching the set temperature. This leads to uneven heating, higher energy usage, and added stress on furnace components. Causes include dirty filters, improper sizing, airflow issues, and faulty sensors.
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