Furnace Not Turning On? Troubleshoot Now

HVAC

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// Posted by Eco Heating & Air Solutions, Inc.

As the temperature drops, many homeowners face a frustrating issue: their furnace won't turn on. If your furnace has been well-maintained, the fix is likely simple and doesn't need a pro. But what's causing your heating system to fail? And how can you quickly find and fix the problem before it gets too cold at home?

Key Takeaways

  • Common reasons for a furnace not turning on include issues with the thermostat, gas supply, power source, airflow obstructions, ignition failure, and safety feature triggers.
  • Troubleshooting the furnace can often resolve the problem without needing to call a professional HVAC technician.
  • Regular maintenance and inspections are crucial to prevent furnace malfunctions and ensure your home stays warm and comfortable all winter long.
  • Knowing when to call for professional furnace repair is essential to avoid further damage and ensure your family's safety.
  • Upgrading to an energy-efficient furnace can save you money on utility bills and provide reliable heating performance.

Understanding How Your Furnace Works

To understand why a furnace may not be turning on, it's key to know its basic operation. When the room gets colder than the thermostat's set point, the thermostat sends a signal. This starts the heating cycle.

The gas valve opens, the ignition turns on, and the furnace warms the air. This air then spreads through the home's ducts. The gases from the burn go through the heat exchanger and out of the house.

The Heating Cycle Explained

The heating cycle of a furnace has several steps:

  1. The thermostat notices the room getting colder than it should.
  2. It tells the control board to start heating.
  3. The gas valve opens, letting fuel to the burners.
  4. The ignition lights the fuel, starting a flame in the combustion chamber.
  5. The heat exchanger takes in the heat from the burn.
  6. A blower fan moves the heated air through the ducts and into the rooms.
  7. The gases from burning are vented out of the house.
  8. When the thermostat thinks the room is warm enough, the cycle stops, and the furnace turns off.

Types of Furnaces

There are many kinds of furnaces for homes, with forced-air gas furnaces being the most common. These use natural gas or propane and heat the air which goes through the ducts. Electric furnaces heat air with electricity, and oil furnaces use heating oil for heat.

Knowing how furnaces work and the different kinds can help homeowners fix problems and keep their heating systems running well.

Troubleshooting: Why Won't My Furnace Turn On?

If your furnace won't turn on, there are several reasons why. By checking common causes and troubleshooting, you might fix it without needing a pro.

Start by looking at your thermostat. Make sure it's set for "heat" and the temperature is higher than the room's. Also, check if the batteries need replacing as a low battery can stop the furnace from turning on.

  1. Check the power supply. Make sure the furnace's power switch is on and the circuit breaker hasn't tripped. If it has tripped, reset it and see if the furnace works.
  2. Inspect the air filters. Dirty filters can block airflow and turn off the furnace. Change them if they're dirty.
  3. Look for any blockages in the ducts or vents. Blocked airflow stops the furnace from working right. Ensure all vents and registers are open and clear.

If the furnace still won't start, it might be gas or ignition system issues. Check the gas line for leaks or problems with the gas valve. Also, a dirty flame sensor might stop the ignition from working.

If you've tried these steps and it still won't work, call a professional HVAC tech. They can find the problem and fix it to get your heating back on.

Regular maintenance and tune-ups are key to keeping your furnace efficient. They help prevent sudden breakdowns during the cold winter.

Thermostat Issues

Thermostat problems are a common reason why furnaces won't turn on. The thermostat is key in telling the furnace when to start and keep the temperature right. If it's not working right, the furnace won't get the signal to heat the house.

Improper Settings

Start by checking the thermostat settings. Make sure it's in "Heat" mode and the temperature is lower than the room's current temperature. If it's not set correctly, the furnace won't turn on, leaving you without heat.

Faulty Wiring or Connections

Thermostat wiring can also be the problem. Over time, it might get damaged or come loose, stopping electrical signals from flowing. Look for any signs of damage or loose connections at the thermostat.

If the thermostat seems to be the issue, you might need a new one or a pro's help. Fixing thermostat problems, like improper thermostat settings or faulty thermostat wiring, can fix the problem and make your furnace work again.

Gas Supply Problems

If your furnace runs on gas, a problem with the gas supply can stop it from lighting up. First, check if the gas is on by looking at the shut-off valve outside. See if other gas-using devices, like your stove, are working. If they are, but your furnace isn't, the issue might be with the gas line or valve to the furnace.

Checking the Gas Line and Valve

Make sure the gas valve is open and the line isn't blocked or broken. This is key to fixing gas supply issues and gas line problems. If the valve is shut or the line is blocked, the furnace won't get the gas it needs to work right. Check the gas valve and make sure it's fully open for gas to flow to the furnace.

If the valve is open and the line looks fine, the issue might be inside the furnace. You might need to call an HVAC expert to find and fix the gas supply issues or gas valve issues you're facing.

Furnace Not Turning On

If your furnace isn't turning on, it might be a power issue. Your furnace needs electricity to work. Check the furnace's power switch to make sure it's in the "on" position.

If the power switch is on but the furnace won't start, a tripped circuit breaker could be the problem. Find the circuit breaker for the furnace and reset it if it's tripped. If the breaker keeps tripping, you might need a professional HVAC technician to look at it.

Power Switch and Circuit Breaker

Make sure the furnace's power switch is turned on. If it is, look at the circuit breaker for the furnace. Reset the circuit breaker if it's tripped. If the breaker keeps tripping, you might have a serious electrical issue that needs a pro.

Experts say 30% of the time, furnaces won't turn on because of circuit breaker problems. This is a common issue that's often fixed by resetting the breaker. But if the breaker keeps tripping, you'll need a pro to check it out.

If you can't fix your furnace after checking the power switch and circuit breaker, call a qualified HVAC technician. They can quickly find and fix any power issues to get your heating working again.

Airflow Obstructions

Proper airflow is key for your furnace to work well. If airflow is restricted, your furnace may not work right. This could even be a safety risk. Look for and fix any airflow blockages in your HVAC system.

Clogged Air Filters

A dirty or clogged air filter often causes airflow problems. Over time, dust and debris can fill the filter, making it hard for your furnace to move air. Check your air filter often and change it if it looks dirty or clogged.

Blocked Ductwork

Blocked ductwork can also cause airflow issues. Gaps, leaks, or debris can limit air flow. This makes your furnace work harder to heat your home. Check your ductwork for blockages, like furniture in front of vents. Seal any gaps or connections to keep airflow strong.

Keeping airflow right is key for your furnace's efficiency. Fixing issues with air filters and ductwork helps your heating system work better. This saves you money on energy bills and makes your furnace last longer.

Ignition Failure

Ignition failure is a common issue that can stop your furnace from turning on. The ignition system lights the gas burners in your furnace. If it's not working right, your furnace won't start. A dirty flame sensor is often the main cause of this problem.

The flame sensor checks for a flame in your furnace. Over time, it can get covered in soot and debris. This stops it from detecting the flame properly. So, the furnace may not light up, leaving you cold.

Cleaning the Flame Sensor Can Resolve Ignition Issues

Cleaning the flame sensor is usually an easy fix. Here's what you can do:

  1. Find the flame sensor, which is usually a metal rod near the burners.
  2. Take out the flame sensor and use fine grit sandpaper or a emery cloth to clean off any buildup on the tip.
  3. Put the cleaned flame sensor back in and try turning on your furnace again.

If cleaning the flame sensor doesn't fix the problem, there might be other issues. These could be with the gas supply or the electronic ignition system. In these cases, it's best to call a professional HVAC technician to find and fix the problem.

Regular maintenance and checks of your furnace can also help avoid ignition problems. Make sure to change your furnace air filters every 90 days. This keeps airflow clear and reduces debris on important parts like the flame sensor.

Don't let a faulty ignition system leave you cold. Watch your flame sensor and call a pro if cleaning it doesn't fix your furnace. With regular maintenance and quick action on ignition issues, you can stay warm and cozy all winter.

Safety Feature Triggers

Your furnace has many safety features to stop dangerous situations like overheating or gas leaks. These features are key but can sometimes make the furnace stop working as a safety step. Knowing how these features work and how to reset them can help you fix your furnace.

The safety float switch is a common feature. It watches the furnace's condensation system and turns off the unit if it finds a blockage or overflow. The high-limit switch also stops the furnace from overheating by turning it off when it gets too hot.

  • The pressure switch checks the furnace's combustion system for airflow problems. If it finds an issue, it will turn off the furnace.
  • The flame roll-out switch turns on if the flames from the furnace go beyond the combustion chamber. This means there might be a problem with the gas or burners.

When a furnace safety feature is triggered, it stops the furnace from starting. To fix this, you might need to clear a clogged line or check the airflow. Sometimes, you'll have to call a professional HVAC technician to find and fix the safety trigger issue.

Knowing how these furnace safety features work and how to reset them lets you fix your heating system. This ensures your home stays comfortable and safe.

Blower Motor Malfunction

When your furnace isn't turning on, a common issue is a faulty blower motor. This motor moves the heated air around your home. Without it working right, the furnace can't spread the warm air, making it shut down.

There are many reasons why your furnace blower motor might not be working. These include a bad capacitor, wiring issues, or needing a new blower motor. If you're facing blower motor issues or furnace blower motor problems, it's smart to get a pro HVAC tech to check and fix it.

Signs your blower motor might be broken include:

  • The blower motor not starting at all
  • The blower motor running on and off or not right
  • The blower motor making strange sounds, like grinding or buzzing
  • The blower motor getting too hot or making the furnace shut down

If you see these problems, act fast to avoid more damage. A pro HVAC tech can figure out the problem and fix or replace the blower motor to get your furnace working again.

Keeping your furnace in good shape, like cleaning the blower parts and changing air filters, can stop blower motor problems. Fixing these issues quickly keeps your home warm and cozy all winter.

furnace not turning on

If your furnace won't start, it can be really frustrating. Before you call a pro, try some troubleshooting steps to fix it. Knowing why your furnace might not start can help you get it working again.

Thermostat problems are a common reason for this issue. Make sure the thermostat is set for "heat" and the temperature is higher than the room's. Also, check if the thermostat has power and the batteries aren't dead.

Gas supply issues can also cause problems. Check that the gas valve is open and the gas line isn't blocked or damaged. If you think there's a gas leak, leave the area and call your gas company right away.

  1. Look at the furnace's power switch and circuit breaker. It might not be getting power, which stops it from starting.
  2. Check the air filters and ducts for any blockages. Blocked filters or ducts can make the furnace shut down for safety.
  3. If your furnace has an electronic ignition, it might be dirty or broken. This stops the burners from lighting. A pro HVAC tech can fix this.

Sometimes, a safety feature might stop the furnace from turning on. This could be a high-limit switch or pressure switch. These turn off the furnace if it gets too hot or if airflow is low.

If you've checked all these things and your furnace still won't start, call a qualified HVAC tech. They can look at your system and find out why it's not working. They'll make sure your furnace is safe and efficient.

Maintenance and Prevention

Regular furnace maintenance and inspection are key to a smooth-running heating system. They help prevent unexpected breakdowns. By caring for your furnace, it works well and reliably when it's cold.

Regular Cleaning and Inspection

Cleaning and inspecting your furnace regularly is vital. This means changing or cleaning the air filter. Dust and debris can block airflow, making the furnace work too hard.

It's smart to have a professional HVAC technician inspect and clean your furnace yearly. This is usually in the fall before it gets cold. They check the furnace's parts like the heat exchanger, blower motor, or ignition system. They fix or adjust anything that's not working right.

Regular furnace maintenance, furnace cleaning, and furnace inspection can make your furnace last longer. It also makes it more efficient and lowers the chance of breakdowns or safety problems. A little effort now keeps your home warm and cozy all winter.

When to Call a Professional

Some furnace problems can be fixed on your own, but others need a pro. Look out for strange smells or sounds from the furnace, water leaks, uneven heating, high utility bills, or if you can't figure out why the furnace won't turn on. These signs mean it's time to call an HVAC expert for help.

They can fix or replace your furnace if needed. This is best done by someone who knows what they're doing.

Signs You Need Repair or Replacement

Watch for these signs that your furnace might need professional help:

  • Strange smells or noises coming from the furnace
  • Water leaks around the furnace
  • Uneven heating throughout your home
  • A spike in your utility bills, indicating decreased efficiency
  • An inability to determine the reason why the furnace is not turning on

It might need fixing or replacing. A skilled HVAC professional can check your furnace and tell you what to do. This could be furnace repair or furnace replacement.

Don't take risks with your family's safety or throw money at bad repairs. If you're facing these problems, call a professional HVAC tech to get it right.

Energy-Efficient Upgrades

If your furnace is old and often breaks down, think about getting an energy-efficient upgrade. New furnaces use less energy and heat your home better. They come with features like variable-speed motors and smart thermostats that make your heating more efficient.

Upgrading to an energy-efficient furnace has many benefits:

  • It uses less energy, which lowers your bills
  • It's better for the planet by reducing emissions
  • You get more consistent and reliable heat
  • You might get tax credits or rebates to help pay for it

Look for furnaces with high AFUE ratings when shopping for upgrades. AFUE stands for Annual Fuel Utilization Efficiency. It shows how much fuel the furnace turns into usable heat. High-efficiency furnaces have AFUE ratings above 90%, meaning they use less fuel and lose less heat.

Think about getting a smart thermostat too. These thermostats can change the temperature for you based on your schedule and preferences. This helps save even more energy and makes your home more comfortable. An energy-efficient furnace with a smart thermostat can cut your heating costs over time.

Talk to a skilled HVAC expert before choosing an energy-efficient furnace upgrade. They can check what your home needs and suggest the best options. They'll also help with the savings and installation details, making sure you're happy with your choice.

DIY vs. Professional Repair

Fixing a furnace that won't turn on can be done by yourself for some tasks. You can check the thermostat, air filters, and power sources. But, issues with the gas supply, ignition system, or inside the furnace should be handled by a professional HVAC technician.

Trying to fix these complex problems yourself is risky. It could also harm the appliance or your home. Knowing when to ask for help is key. Stick to simple maintenance tasks yourself, and let experts handle the hard stuff.

  • DIY tasks include changing air filters, vacuuming, cleaning the pilot light, and clearing vents.
  • Experts should deal with gas lines, electrical wiring, or other risky tasks.
  • Getting a professional furnace repair service every year is a good idea. It keeps your system safe and efficient.

Knowing when to do it yourself and when to call a pro keeps your heating system safe and working right. This is important for staying warm during the winter.

Preparing for Winter

As winter comes, make sure your furnace is ready to keep your home warm. This means getting a furnace maintenance check-up, changing the air filter, and fixing any issues found before winter. Doing these things can stop your furnace from breaking down when you need it most. This keeps your family safe and warm during the cold months.

It's key to keep your furnace in good shape for it to work well and save energy. Experts say you should get a professional to check it at least once a year, right before it gets cold. They'll clean the furnace, look for problems, and make sure everything works right.

Changing the air filter is also important. A dirty filter can make your furnace work too hard and use more energy. You should change the filter every 1-3 months, depending on how much you use your furnace and the air quality in your home. This easy step can really help your furnace last longer and work better.

  • Schedule a professional furnace inspection and tune-up before winter
  • Replace the air filter every 1-3 months to maintain airflow and efficiency
  • Address any issues identified during the pre-winter maintenance check

By doing these things, you make sure your furnace is ready for winter. Regular maintenance and being careful can stop unexpected problems and keep your family safe and warm during the cold months.

Conclusion

A furnace not turning on can be really frustrating. But, with the right furnace troubleshooting steps, many homeowners can fix the issue on their own. By understanding how your furnace works, checking for common problems like thermostat issues, gas supply problems, and airflow obstructions, and keeping up with furnace maintenance like cleaning and inspections, you can keep your home warm and cozy all winter.

If you can't figure out the problem or it keeps happening, it's best to call a qualified HVAC technician. They can do a deeper check and provide furnace repair. Some furnace problems need a pro to fix them safely and right, especially with gas-related parts or complex issues.

Regular maintenance and quick action on furnace problems can stop system breakdowns. It can also make your system more energy efficient and might save you money on your bills. By being proactive with your heating system, you can have a warm and comfy winter without the hassle of a furnace that won't work.

Electric Heat pump outside
About Eco Heating & Air Solutions, Inc.
Residential and light commercial heating, cooling, air quality, and plumbing are specialties at Eco Heating & Air Solutions, Inc. We provide home and business owners in Oak Ridge, TN and surrounding areas free estimates, service of all makes and models, and trusted solutions to everyday requirements.

We are an eco-friendly, award-winning company and uphold Better Business Bureau accreditation. Our team of professionals is NATE-certified, drug-free, and dedicated to earning your approval and loyalty.

FAQ

What are some common reasons why a furnace may not be turning on?

Common reasons include thermostat issues, gas supply problems, and circuit breaker or power switch issues. Other reasons are airflow obstructions, ignition failure, and safety feature triggers.

How does a furnace's heating cycle work?

The heating cycle starts when the indoor temperature drops below the thermostat's set point. The thermostat signals the control board to start the heating process. The gas valve opens, the ignition turns on, and the fire warms the air. This air is then spread through the home's ducts.

What types of furnaces are commonly found in homes?

Most homes have a forced-air gas furnace.

How can I troubleshoot thermostat issues that may be preventing my furnace from turning on?

First, make sure the thermostat is set to "Heat" mode and the temperature is below the room's temperature. Check the wiring for loose or damaged connections. If the thermostat seems to be the problem, you might need a new one or professional help.

What should I do if I suspect a problem with the gas supply to my furnace?

Check the shut-off valve outside to see if the gas is on. Make sure other gas appliances like the stove work. If they do, but the furnace doesn't, check the gas line or valve to the furnace. Ensure the valve is open and the line isn't blocked or damaged.

How can I troubleshoot power-related issues that may be preventing my furnace from turning on?

First, check the power switch to make sure it's on. If it is and the furnace still won't start, the circuit breaker might have tripped. Reset it if you can. If it keeps tripping, you might need a professional to look at it.

What can I do if I suspect airflow obstructions are causing my furnace not to turn on?

Start by checking and replacing the air filter if it's dirty. Look for any blockages in the ductwork. Seal any gaps and remove any debris or furniture blocking the vents and registers.

How can I troubleshoot an ignition failure that is preventing my furnace from turning on?

A common issue is a dirty flame sensor. This safety device checks for a flame. Clean the flame sensor to fix the ignition failure.

What safety features on a furnace can cause it to shut down and how can I reset them?

Furnaces have safety features like the safety float switch and high-limit switch. If these are triggered, the furnace will shut down. You might need to reset these features to get the furnace working again.

When should I call a professional HVAC technician to address my furnace not turning on?

Call a professional if the problem persists or you can't figure it out yourself. Signs you need help include strange smells, noises, water leaks, uneven heating, or a spike in bills. If DIY fixes don't work, you'll need expert help.

Electric Heat pump outside
About Eco Heating & Air Solutions, Inc.
Residential and light commercial heating, cooling, air quality, and plumbing are specialties at Eco Heating & Air Solutions, Inc. We provide home and business owners in Oak Ridge, TN and surrounding areas free estimates, service of all makes and models, and trusted solutions to everyday requirements.

We are an eco-friendly, award-winning company and uphold Better Business Bureau accreditation. Our team of professionals is NATE-certified, drug-free, and dedicated to earning your approval and loyalty.

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