Furnaces were designed with one job in mind: to heat our homes any time temperatures plummet. Unfortunately, like any complex piece of machinery, components can wear out or malfunction, leaving us with a giant hunk of metal that does nothing more than take up space. So, what do you do when your furnace refuses to turn on and heat your home? Our expert technicians at H.J. Faust are here to explain the top reasons why furnaces stop turning on and what you can do about it.
1. The Air Filter Is Clogged and Dirty
Your furnace’s air filter is designed to trap dust, pollen, pet dander, and other airborne particles to prevent them from circulating through your home and from clogging the sensitive internal components of your HVAC system. Naturally, this filter becomes saturated with debris over time. When it gets excessively dirty, it will restrict airflow and overheat the heat exchanger.
Today’s residential furnaces are equipped with a safety feature called a limit switch that detects excessive heat and shuts the entire system down to prevent a fire hazard or serious damage to the unit. If a dirty filter is the culprit behind your system not heating your home, you might notice the furnace runs for a short period, then shuts off, and repeats this cycle over and over.
What You Can Do
Most filters are located in a slot on the side or bottom of the furnace cabinet. Simply slide the filter out and check it for a thick layer of dust. If needed, insert a new or clean filter, making sure the arrows on the filter frame point in the direction of the airflow. We recommend checking your filter monthly and replacing it at least every 90 days.
2. The Thermostat Is Malfunctioning
The thermostat tells your furnace when to turn on and off to maintain your desired temperature. So, if the thermostat isn’t communicating correctly with the furnace, your system won’t work. In many cases, the problem can simply be traced back to a dead battery or an incorrect setting.
What You Can Do
First, ensure the thermostat is set to “Heat” and the temperature is set at least five degrees higher than the current room temperature. If the screen is completely blank, try replacing the batteries.
If your furnace won’t kick on even after these simple fixes, the problem may lie with the thermostat’s wiring or internal components, which will require a professional diagnosis.
3. The Pilot Light or Ignition System Has Failed
For a gas furnace to produce heat, it must first ignite the fuel. Older furnaces use a standing pilot light (a small, constantly burning flame) to ignite the burners. If this flame goes out, the furnace’s safety mechanisms will prevent the main gas valve from opening, and the furnace won’t light.
For modern gas furnaces, electronic ignition systems are used. This could include either an intermittent pilot or a hot surface ignitor. The intermittent pilot uses an electric spark to light the gas only when needed, while a hot surface ignitor works much like a lightbulb filament, glowing red-hot to ignite the burners. These components can fail over time due to wear and tear, cracks, or electrical issues, preventing the furnace from starting up.
What You Can Do
If you have an older furnace, you can visually inspect the pilot light assembly to see if the flame is out. Your furnace should have instructions on the service panel for relighting it. However, if the pilot won’t stay lit, you will need to call a professional for a furnace repair.
For electronic ignition systems, troubleshooting is best left to a professional, as it involves working with the furnace’s electrical and gas systems. So, if your furnace is not turning on, get in touch with the experts at H.J. Faust.
4. A Circuit Breaker Has Tripped
Although your furnace may be powered by natural gas or propane, its essential components (like the blower motor, electronic ignition, and safety controls) all run on electricity. If the furnace isn’t getting any power, it won’t be able to turn on at all. This loss of power is often caused by a tripped circuit breaker or a blown fuse.
What You Can Do
Locate your home’s main electrical panel. Look for the breaker that is labeled “Furnace,” “HVAC,” or “Air Handler.” If the switch is in the “Off” position or in the middle, switch it completely off and then back on again. If the breaker trips again immediately, do not reset it. This problem often means there’s a more serious electrical issue at play. A professional will need to make a proper diagnosis and repair.
If your home has an older fuse box, check to see if the corresponding fuse has blown and needs to be replaced.
5. There’s Been an Interruption in Gas Supply
Is your gas furnace not turning on? The problem could be a gas supply interruption.
For a gas-powered furnace to create heat, it needs a continuous supply of natural gas or propane. If this supply is interrupted, the furnace’s sensors will detect the lack of fuel and will not allow the ignition sequence to begin as a safety measure.
In many cases, the gas supply could have stopped flowing because the gas valve leading to the furnace was accidentally turned off. Alternatively, there could be an issue with the gas line or the supply from your utility provider.
What You Can Do
Check the gas valve on the line that runs to your furnace. The handle should be parallel to the pipe, which indicates it’s open. If it’s perpendicular to the pipe, it’s closed.
If the valve is open and you suspect a wider gas supply issue (e.g., other gas appliances in your home aren’t working), you should contact your gas company immediately.
Why You Should Leave Major Repairs to a Professional HVAC Technician
It can be tempting to try a DIY repair when your heater is not turning on, especially if you’re worried about staying warm on a cold Wisconsin night. However, furnaces are complex systems, and attempting to fix them without proper training and tools can be dangerous and costly.
Instead of risking your comfort and safety, let a professional HVAC technician handle the repairs for you. At H.J. Faust, we will examine the entire system to identify potential problems before they cause a breakdown. This not only saves you time and stress but also helps extend the life of your heating equipment. Plus, our professional repairs keep your manufacturer’s warranty intact and ensure your home stays safe from gas leaks, fire, electrical shock, and dangerous fumes.
Furnace Not Turning On Automatically? Call Our Pros for Help!
Are you ready to crank up the heat in your home, but your furnace seems to have other ideas? The team at H.J. Faust is here to provide furnace repairs and replacements when your heating system refuses to kick on. We’ll have your home all nice and cozy in no time.
Contact us today for reliable furnace services in Burlington, WI, and the surrounding areas! We look forward to restoring your comfort and peace of mind during this winter season.
