What Should You Do if You Experience Any of These Heating Problems?

When the temperature outside plummets and winter is upon us, the heating system that warms your Louisville home will become more important than ever before. Trustworthy heat pumps, furnaces, and thermostats are crucial to staying comfortable and safe when the temperatures are low, but even the best systems experience issues from time to time.

When you know how to spot issues and the furnace troubleshooting steps to take, common furnace problems feel less scary. Save time and money knowing when to call in a little help and avoid discomfort at home this winter. Jarboe’s Heating, Cooling & Plumbing believes in empowering homeowners with the information needed for easy furnace troubleshooting. When top furnace problems aren’t so easily solved, turn to us for fast, effective, and trusted support.

Using This Guide

The common heating and furnace issues detailed below are grouped by common symptoms you might come across. It is important to note that while some issues can be repaired and resolved quickly and easily, others require more in-depth diagnostics, repairs, or replacements, which should be completed by an HVAC professional. Understanding the culprits of a furnace not working could help you to prevent future issues, extend the life of your system, and protect your family from fire or carbon monoxide exposure. Never hesitate to call us with your questions. We have a team on hand 24 hours a day, 7 days a week, 365 days a year.

20 Most Common Heating Problems

Search the list below for common heating issues and their probable causes. Learn what to do next to correct problems with your heat pump or furnace.

1. Adjusting Your Thermostat Doesn’t Start Your Furnace

Anytime you change a setting on your thermostat, your furnace or heat pump should respond appropriately. However, if adjusting your thermostat doesn’t start your heating system and warm your home, this top furnace problem could be caused by one of these issues:

Locked thermostat. Some modern thermostat models have lock functions to allow parents, business owners, and landlords to limit thermostat adjustments. If you try to turn on your furnace and the thermostat isn’t responding, look for a lock icon. If the system is locked, follow the instructions in your owner’s manual to unlock the system and make the appropriate adjustments.
System on “AUTO.” Automatic operation modes are included on some thermostat models, made to keep your home at an even, steady temperature by automatically triggering the furnace or heat pump. When “AUTO” mode on, adjustments you make may not change anything. Try switching your thermostat back to “HEAT” to see if you are able to make the appropriate adjustments.
Loose electrical connections. Wiring inside of your thermostat can become dirty or pushed out of place due to everyday use. When electrical connections are loose or dirty, they can’t relay necessary information, and your adjustments don’t translate into heating. Clean your thermostat carefully by dusting the interior with a gentle spray of canned air and tighten any loose connections with a screwdriver.
Home or power problems. Tripped breakers or blown fuses can prevent furnaces from powering on. Check your home breaker box for tripped breakers and replace any blown fuses inside your fuse box. Check the ON/OFF switch located on or nearby the furnace, air handler, or outdoor heat pump unit to make sure the system is on and ready to go. If your area is experiencing a power outage, you’ll have a furnace that doesn’t work until the power is restored. Contact your power company to report the outage and to get a timeline estimate for when you can expect power again.
Incorrect thermostat placement. Thermostats should be placed in an area where they can accurately detect the ambient temperature of the space. If thermostats are placed in an area subject to drafts, direct sunlight, heat from kitchen appliances, or stagnant air, they may not sense temperatures correctly. Check the thermostat installation guidelines in your owner’s manual, and ensure your system is placed appropriately. If you suspect it isn’t where it should be, call in an HVAC technician to relocate your thermostat.
Unlevel installation. Proper installation can also impact a thermostat’s ability to gauge the temperature. If the unit is unlevel or doesn’t fit properly in its base, it may not detect the temperature accurately or could struggle to relay messages to your furnace. If your thermostat isn’t responding appropriately, remove it from its mount, re-seat the thermostat, and see if it sits flush with the wall. If it doesn’t seem to be connecting correctly, call in a technician to adjust its installation.

2. Warning or Service Message on Thermostat Display

Many modern thermostats are designed to alert homeowners about everything from necessary heating maintenance and performance problems to connectivity errors. While thermostat error messages can be very helpful, they vary significantly between models and brands.

Anytime you see error messages on thermostat displays, it is important to look up the error in your thermostat’s user manual so you understand what the thermostat is trying to tell you. Many error messages have codes, so check the number against the error message list in your manual. Depending on why your thermostat sent an alert, the manual may give you directions for clearing the code, or direct you to contact a professional for additional help.

3. Thermostat Screen Blank or Not Turning On

Your thermostat acts as the brain to your home heating system. If it won’t turn on, it can’t tell your furnace or heat pump when to turn on, which leaves you without heat at home. Here are a few reasons your thermostat may not be turning on, one of our most common heating issues.

Lack of power. One of the most common reasons thermostats sometimes become unresponsive is a lack of power. If your system is battery-powered, replace the batteries to see if your thermostat screen turns on. If your unit is hardwired, check your electrical panel to see if you have any tripped breakers or blown fuses. To correct a tripped breaker, flip it in the opposite direction, and then turn it back to face the inward section of the panel. Replace blown fuses with new ones. Local power outages can also disrupt your thermostat, so check to see if other electrical appliances and lights in your home are working properly.
Loose internal wiring. Anytime wiring comes loose inside a thermostat, it can impact what appears on the screen. After removing the faceplate of your thermostat, look for any loose connections or wires that appear to be out of place. Tighten any connections and replace the thermostat cover. If the screen is still blank, ask an HVAC technician to come in and test the circuitry. In some cases, it may be necessary to replace the unit.
Thermostat set incorrectly. Thermostat settings may be adjusted by family members or friends without your consent or knowledge. If the screen is off or the unit is unintentionally turned off, the display may be blank. Check the thermostat to make sure it is seated properly, turned on, and set appropriately.
Overheating furnace. When a thermostat screen turns off or goes blank in the middle of a heating cycle, your furnace may be overheating. High internal temperatures can trigger your furnace’s limit switch, halting the furnace. Overheating can be caused by blocked vents or dirty filters – replace the filter and remove any vent obstructions. If your furnace keeps overheating, consult with a professional to find the cause.
Tripped float switch. Condensing furnaces make more efficient use of combustion heat, which also means gases convert to liquid within the system and must drain out. These systems have an internal float switch linked to the thermostat to prevent moisture damage if there is a buildup of water in the system. If the float switch is triggered, the thermostat will turn off. Look for clogs and remove them from the drain line, then reset the float switch to see if the thermostat and furnace powers back on. If the float switch continues to trip, have an HVAC technician repair or replace the condensate drainage line to fix the problem.
Open access panels. To protect homeowners and prevent system damage, some furnace systems and thermostats are designed to shut off entirely if access panels are loose. Honeywell thermostats are especially prone to this. If your thermostat is not displaying any text, check the access panels on your thermostat to see if they are closed tightly.
Damaged or faulty device. If furnace troubleshooting doesn’t seem to do the trick, the thermostat may need to be completely replaced. Fortunately, the thermostat is the least expensive component of the HVAC system. Keep in mind that most thermostats have a lifespan of around 10 years. While you can install a thermostat yourself with help from your owner’s manual, professional installation ensures effective and efficient operation.

4. Furnace Won’t Turn On

When you switch the heating on in your home, you expect your system to start up right away. If it doesn’t, you may worry that the system is damaged, or worse, broken. However, there are often very simple reasons behind your furnace not working. Here are a few reasons your furnace may not be switching on appropriately.

Ajar access doors. Your thermostat isn’t the only system that may not start if there are open access doors on your furnace. If any panels are out of their proper place, certain heating systems are designed to stay off to protect the system. Check the doors to your furnace or air handler’s blower compartment. If a panel has popped out of place or is missing a screw, remedy the problem and try to start the system again.
Incorrect thermostat settings. Check your thermostat to see if it is set to “HEAT” and not “COOL.” If your system is set to “COOL,” the thermostat is probably not using the temperature setpoints you intended for heating – instead, cooling settings are active. Try switching the unit to “HEAT” and changing the temperature to see if it turns on.
Thermostat not receiving power. If your furnace doesn’t turn on, there may be a problem with your thermostat powering on. Since thermostats are designed to sense the ambient temperature and send the call to your furnace, a thermostat that isn’t powering on appropriately is not able to turn on your heating system. Try replacing your thermostat’s batteries, tightening electrical connections inside the thermostat, and making sure the thermostat is seated appropriately. If there are problems with the wiring or the thermostat seems loose, have a professional take a look at it.
Furnace itself not receiving power. Furnaces and heat pumps need power to switch on and operate. Check your breaker box for tripped breakers, and make sure the auxiliary power switch on the furnace, heat pump, or air handler itself is switched on. There is also a fuse inside most furnaces that regulates electrical conductivity. Check the fuse to see if it looks broken or burned, and if it does, replace it. If your furnace isn’t powering on, and you can’t find the source, contact a professional.

5. Airflow Problems from Your Heating Vents

Anytime you turn on your furnace and it turns on, but there isn’t a lot of airflow coming out of the vents in your home, it is important to check a few key areas that are commonly to blame for this top furnace problem. Here are a few issues you should check for, and when to call in a professional.

Closed vents. To give homeowners more control over the temperature of their space, many vents have louvers that can be opened or closed. In general, louvers should be kept open so your home’s HVAC system has the opportunity to heat your home evenly. However, if you notice that some of your vents aren’t blowing air into your home, check them to see if they have been closed, or partially closed. Some louvers are very easy to accidentally close, especially if they are old or have become loose. If louvers become stuck closed, vent covers should be replaced.
Lack of air return vents. HVAC systems are designed to balance your home’s climate by using air returns to bring air back to your furnace. However, too few air returns can create a shortage of air moving to your furnace which prevents proper heating across the home. This problem is more complex to fix since it involves installing new vents. If your home has poor airflow and you suspect inadequate return air vents, call your HVAC professional for inspection.
Clogged ductwork. Obstructions in a duct can cause heated air not to reach it’s intended destination. Ducts can develop clogs due to a buildup of dust and debris. If the duct runs become loose or disconnected, the air pressure can suck in debris like insulation from unconditioned areas and move it into the run. Clogs that are close to vents may be able to be reached and removed. However, if clogs are deep within the lines, you may need professional duct cleaning to remove debris.
Leaks in ductwork. When ducts develop damage that allow heated air to escape, airflow can suffer. Leaky ducts are thought to account for as much as 30% of lost heat within a home. If you have poor airflow coming from vents, check visible ductwork and patch it with foil tape. If you don’t have accessible ductwork, ask a professional to test for leaks and perform duct sealing.
Clogged furnace filters. Air filters become laden with dirt over time. When they become clogged, they disrupt the airflow moving through the system. Anytime you notice airflow problems, check your air filter to see if it looks dirty. HVAC filters should be examined at least every month, and replaced periodically. Never use HEPA filters for your home, since they may restrict airflow enough to harm your furnace.
Blower motor problems. Furnaces have a blower motor that moves heated air through the ducts and into the rest of your home. However, grime buildup, loose or broken fan belts, worn-out motor bearings, motor capacitor problems, or a faulty fan belt pulley can make your blower motor malfunction. While it is possible to troubleshoot and test the blower motor with help from your furnace manual, professional repair or replacement is recommended.
Damper problems. Some furnaces use automatic or manual damper systems to further regulate air movement. However, damper louvers may stick, restricting airflow. Check the manual dampers in your home to see if they are stuck, and free them, if possible. If you have an automatic damper system that is controlled by a thermostat, you need professional testing and repairs.

6. Furnace System Stays on, and Won’t Shut Off

While furnaces can make your home warm and toasty, a system that won’t shut off is a problem, too. If it seems like your furnace is always running, here are a few issues that could be to blame for this common heating problem:

Thermostat problems. If your heating system isn’t turning off, your thermostat may not be communicating properly with your furnace or heat pump, causing the system to stay engaged in a heating cycle. Thermostat wiring may need to be repaired, or the system may need to be replaced.
Limit switch issues. Furnace limit switches may be stuck which makes the blower motor to run around the clock. You may reset the limit switch to see if that solves the issue, or ask an HVAC tech about replacement.
Incorrect fan settings. If your furnace won’t turn off, your system’s fan could be set to “ON” instead of “AUTO.” When the fan is on “ON,” it will run to circulate air all the time – in “AUTO” mode, it only runs to circulate heated air when the furnace or heat pump is in a heating cycle. Set your thermostat to “AUTO” to correct this issue.
Damaged compressor contractor. Heat pump compressor contractors are designed to regulate the power running to the system. If this component is damaged, it may continue sending power, even after the desired temperature has been reached. Compressor contractors need to be professionally replaced.

7. Furnace Won’t Ignite

When furnaces are powered and set properly, it should turn on as soon as the temperature set on the thermostat is reached. However, if the furnace doesn’t ignite, the home won’t receive any heat. Here are a few simple reasons your furnace won’t ignite and how to fix simple ignition issues.

Damaged ignitor component. Ignitors inside your furnace are designed to spark the fuel inside your system to generate the controlled flame that creates heat for your conventional furnace. However, ignition components can sustain damage due to wear and tear, and the system may have small electrical components that can go out. If your furnace isn’t igniting, a professional HVAC contractor can test the component and replace it when it becomes damaged.
Incorrect ignitor installed. If the wrong ignitor is used, the component may not have the proper voltage, which can lead to the premature failure of the ignition system. Professionals can look up the proper ignitor for your system and replace it with the right one.
Pilot light extinguished. Furnaces older than 10 years may rely on a pilot ignition system. These pilot lights generate a constant-burning flame, which ignites the fuel inside your furnace when the thermostat triggers the system to turn on. However, drafts, ground movement, or faulty thermocouples may extinguish the pilot light. If you have fuel source issues, your system may not have access to enough fuel to keep the pilot light lit, which could allow natural gas to leak into your home. Extinguished pilot lights should be handled immediately. Follow instructions in your owner’s manual to relight the pilot.
Dirty ignition. Combustion can generate soot, which can cause carbon to accumulate on the ignitors. Over time, this added dirt can interfere with proper lighting. If you hear a repetitive clicking sound when you turn on your furnace, contact an HVAC professional to clean this fragile component.
Cracked hot surface ignitor element. Your furnace will not start if the hot surface ignitor’s heating element has cracked. These components typically last from 3-5 years and require periodic replacement. Hot surface ignitor elements may need to be replaced sooner when mishandled or if the system short cycles. While careful homeowners may choose to replace this element, an HVAC technician can be called on to help.
Damaged limit switch. Limit switches inside furnaces are designed to stop operation if the interior of the furnace reaches unsafely high temperatures. Limit switch malfunctions can prevent ignition. Limit switches can sustain damage due to poor airflow or dirty filters, so check your filter routinely and replace it as needed. Damaged limit switches need to be replaced by an HVAC professional.

8. Heating System Turning off Too Soon

Typical heating cycles operate for between 10 to 15 minutes. If your furnace or heat pump turns on and then shuts down quickly afterwards, it experiences a common heating issue called short cycling. While it may seem inconsequential, short cycling can tax your furnace and HVAC system. Here are a few causes of short cycling in furnaces:

Furnace equipment too large. Furnaces should be sized appropriately for a home. Before a furnace is installed, professionals carefully calculate the necessary heat load for a space and take into account things like the number of doors, windows, and rooms. If furnaces are too large for a home, the system can heat up air close to the furnace too quickly, and cycle off again before it has the chance to spread through your home. Professional HVAC replacement is the only solution for an oversized system.
Poor airflow. Clogged HVAC filters can impede airflow, which can tax the furnace. Poor airflow can cause the furnace’s limit switch to trip, which can shut down the furnace early. HVAC filters should be replaced according to the schedule recommended by the filter manufacturer but sooner if they look dirty. To ensure proper airflow, make sure all vents are open throughout your home.
Thermostat issues. Dirty temperature sensors, faulty electrical connections, and poor thermostat placement can cause a device to inaccurately gauge the ambient temperature, which could trigger your furnace to turn off early. Unlevel mercury thermostats can also cause short cycling. If your thermostat is having problems, clean the system carefully or consider recalibrating, repositioning, or replacing the unit to solve the issues. HVAC professionals can troubleshoot or replace your system for you.
Incorrect thermostat anticipator calibration. Older thermostats often have adjustable heat anticipators designed to stop the flow of heat early, since residual heat can remain in the ducts. However, calibration may be needed so they can operate properly. If your furnace is short cycling, ask an HVAC pro to calibrate your thermostat, or update your thermostat altogether to eliminate this top furnace problem.
Damaged flame sensor. Flame sensors are built into furnaces to detect the presence of a flame and cut the flow of fuel in the event the flame goes out. However, if this sensor becomes dirty, it may not detect the flame properly, and shut down your furnace as a precaution. Flame sensors can be tested, cleaned, or replaced by a professional.
Damaged furnace draft inducer motor. Some furnaces have a draft inducer motor designed to exhaust combustion gases that may have lingered from the previous heating cycle. Governed by an air pressure switch, draft inducer motors may shut down the furnace early if they malfunction. These malfunctions can be caused by obstructions in the flue pipe, or because of a small electrical fault within the pressure switch. Either repair should be handled professionally.

9. Furnace Generates a Lot of Noise

While you may be used to a pushed air noise as your furnace or heat pump operates, other sounds may be difficult to ignore, especially if you are trying to sleep. If you notice new sounds, they could be caused by these top furnace problems:

Out-of-place panels. Furnace housings have several panels that may need to be removed during service. If these panels aren’t properly attached, they can rattle as the system runs. Check your furnace for missing screws on the panels, or metal panels that have popped out of place.
Ignition issues. Faulty ignition systems may not burn fuel properly right away – you’ll probably hear repeated clicking if the ignition isn’t starting properly. If the system delays ignition for long enough, fuel can accumulate and ignite all at once to create a large banging noise. Furnaces that generate banging or explosion noises should be corrected by an HVAC professional.
Fan belt slippage. When fan belts of the motor slip, they can create a squealing noise when your furnace or air handler runs. Fan belts may need to be tightened or replaced by a pro if they develop problems.
Unlubricated or damaged motor bearings. Motor bearings need to be lubricated to operate silently. If motor bearings develop damage, they may need to be replaced. Motor bearings should be oiled every year to make your motor runs silently.

10. Furnace Generates Cold Air Instead of Warm

If your furnace operates, but the current temperature on your thermostat never seems to budge, you may be having furnace trouble. Here are a few things that could cause your heater to generate cold air:

Large duct leaks. If large leaks are present in duct runs, large amounts of heat can escape from your ducts into other spaces, such as the voids inside of your walls. Unheated air can also be sucked into the vent lines, which can make air moving into rooms feel much cooler. Drastic heat loss like this can also increase power bills. If you suspect duct leaks, check visible duct lines for gaps between joints, holes, or other issues, and seal the areas with HVAC aluminum tape. Professionals can also pressure test your system to find and seal leaks.
Blower fan on wrong setting. Blower fans have two settings: “ON” and “AUTO.” While “AUTO” is designed to turn on the blower fan only during heating or cooling cycles, “ON” runs the fan continuously. If cold air is coming from your vents, the blower fan may be set to “ON,” blowing cold air sometimes, and will warm up when a heating cycle starts. To fix the problem, switch your system fan to “AUTO” instead.
Shut gas valve. Gas valves may be closed due to a leak or preparing to leave your home for a long period of time. However, a closed gas valve will prevent your furnace from getting the fuel it needs to combust and produce heat. Closed gas valves sit perpendicular to the pipe, while open valves are in line with the direction of the valve. Check to see if your valve is open and open it if necessary.
Damaged ignition. When ignition systems are damaged, they may not produce the flame necessary to combust heating fuel and warm your home. Ignition issues can have lots of potential causes, including unlit pilot lights and malfunctioning components. Refer to section seven for more information on damaged ignition systems. Damaged ignition may be resolved carefully by following the directions outline in your owner’s manual, but it’s always safer to work with a professional.
Clogs in the condensate line. High-efficiency condensing furnaces expel combustion byproducts by way of condensation. These systems can accumulate water that can trip a limit switch if too much water accumulates due to a clog in the condensate line, shutting down heat production. Proper drainage must be restored to move water out of the system properly. Check your condensate line for clogs and place a service call if you can’t free the clog on your own.
Dirty air filter. Dirty air filters can block airflow, which can cause your system to overheat. When this happens, some elements of your furnace or heat pump may operate, while others may not, causing cold air to blow into your home. Check air filters regularly, and replace them at least once every three months, or as soon as they look dirty.
Not enough heating fuel. Many furnaces use natural gas, liquid propane, or heating oil as fuel to combust and generate heat. If your fuel reserves are out or low, your furnace simply may not have enough fuel to generate this heating response. Refill your fuel stores to correct the problem or contact your gas company to ask about utility outages or damage to lines.

11. Heat Pump Isn’t Warming Home

Many families throughout the greater Louisville, Kentucky area rely on heat pumps all throughout the winter. However, if you turn on your heat pump system and your home doesn’t warm up, one of these problems could be at fault:

Damaged starting components. Heat pumps may not turn on because the starting capacitor is bad, which prevents the motor from receiving electrical power. Sometimes, this issue also causes the system to generate a clicking noise at startup. Bad starting capacitors should be replaced by a professional.
Clogged HVAC filters. HVAC filters allow proper airflow throughout your system. If your filter is clogged or dirty, your heat pump may not operate properly. Air filters should be replaced at intervals recommended by the manufacturer, and typically more frequently during the winter, when systems are used heavily.
Dirty outdoor unit. Heat pumps extract warmth from the air outside. However, if your heat pump is covered with leaves, snow, or yard debris, it can prevent efficient heating. Clean off your outdoor unit to see if that fixes the problem.
Improper blower fan settings. Check to see if your blower fan is set to “ON” or “AUTO.” If your system is set to “ON,” the unit may blow cold air between heating cycles. Change your system to “AUTO” instead.
Improper thermostat settings. Make sure your thermostat isn’t unintentionally set to “COOL” or “OFF.” Update your thermostat settings to fix the problem.
Refrigerant leaks. Refrigerant is a liquid that transfers heat from outside to indoors during winter, and from indoors to outside during the summer. If refrigerant levels are low due to a leak, your heat pump may not be heating properly. Leaks must be repaired and the system recharged. Refrigerant recharging should only be conducted by a professional with their EPA certification since refrigerant released into the atmosphere can damage the environment.
Unit is in a defrost cycle. Heat pumps have a defrost cycle to melt away ice outside. When this cycle is running, it operates in cooling mode to warm the outdoor coil. During this period, backup heating should be used.
Heat pump covered in ice. The defrost cycle on your heat pump may not be powerful enough to melt away thick layers of snow and ice. If your heat pump is covered in ice and snow, clear those accumulations manually before turning back on your heat pump.
Stuck reversing valve. Heat pump reversing valves switch your unit from heating to cooling mode when the seasons change. If your valve is stuck, it may be continuing to run in cooling mode. Stuck reversing valves should be professionally replaced.
Frigid outdoor temperatures. Heat pumps are more efficient in warmer temperatures. Anytime the outdoor temperature falls below 25 degrees Fahrenheit, your system may not be able to adequately heat your home. Use supplemental heating systems during these periods or choose a heat pump specially designed for colder climates.

12. Cold Spots Throughout Your Home

If you feel like some parts of your home are cold, while others are uncomfortably warm, your HVAC system may have some balance problems. Here are a few reasons the areas in your home may be improperly heated:

Undersized heating system. Small conventional furnaces, heat pumps, or oil furnaces may not be large enough to heat your entire home, especially if additions have been made to your home. You can correct an undersized heating system by adding a secondary heating system like a ductless mini split to specific areas, or by replacing your existing unit.
Oversized heating system. Furnaces that are too large for a home can warm the air close to the furnace too fast, which signals the thermostat to turn off early before temperatures throughout your home even out, causing short cycling. To correct this problem, furnaces will need to be replaced by an appropriately sized unit.
Dirty air filters. Air filters that become clogged and covered in dust limit airflow, which can make some parts of your home cold. Check air filters frequently, and replace them whenever they look dirty, which could be as often as every month during the winter.
Duct obstructions. Room vents can become blocked on accident by area rugs, furniture, carpets, and other household objects. Ducts can also become clogged if debris falls into floor registers. These obstructions prevent air from reaching its destination. Check air vents in your home to make sure they are open, clean, and not impinged by other furniture or items.
Duct leaks. Duct leaks can make it easy for heat to escape, which can reduce the amount of heat sent to the rooms of your home. Leaks can be caused by physical damage, collapsed duct runs, or loose joints. Check visible ducts for damage and seal the area with aluminum HVAC tape. If you can’t find damage, request professional duct inspections and sealing.
Stuck dampers. Some furnaces rely on damper systems to help regulate airflow throughout your home. If manual dampers become stuck or automatic dampers are malfunctioning, they can block airflow to certain rooms. Check manual dampers to see that they are operating properly and consult with a professional if dampers appear closed and your automatic system isn’t responding.
Uninsulated ducts. As warm air travels through cold air ducts, heat can leach out when in contact with cold metal, reducing the amount of heat moved to rooms. To prevent this problem, insulate your air ducts, especially in colder areas like attics, basements, and within walls on the outer perimeter of your home. Long runs are especially prone to heat loss since the warm air will have to travel farther. Ask an HVAC professional for help insulating runs if you aren’t sure how to proceed.
Poor duct system design. Air ducts should be sized appropriately to move the necessary air throughout your home. If duct systems are designed too large or too small, it could impinge airflow. The only way to correct this problem is to have a professional replace the incorrect venting.
Thermostat location. Thermostats should be able to detect ambient temperatures to signal to the heating system when to turn on and switch off. However, if your thermostat is in an area prone to temperature swings, direct sunlight, drafts, or stagnant air, it may not be able to do its job. Check your thermostat’s location and compare it to the recommended installation area in your owner’s manual. In some instances, your thermostat may need to be professionally moved.
Blower fan speeds. If your air handler or furnace has a multi-speed or variable-speed blower, the system may need to be adjusted to deliver the proper amounts of heated air. While it is possible to adjust multi-speed blowers on your own, it is easier with the help of a professional.
Inadequate insulation. If your home isn’t insulated sufficiently, rooms can struggle to retain their heat, which can cause cold spots. Consider adding more insulation to your attic or basement to improve your home’s ability to stay warm.
You live in a multi-level home. Homes with multiple levels are notoriously difficult to heat, because of warm air rising. Consider upgrading your home heating system with a zoning system to even out temperatures.
Old heating system. Conventional gas furnaces last between 15-20 years, while heat pumps last from 10-15 years. If your furnace is older, it may not be as efficient as it needs to be to heat your home evenly. Consider upgrading your furnace to improve comfort.

13. Your Heating Bills Are High

Steep heating bills can be caused by all kinds of reasons, including bad habits from family members like leaving windows or doors open. However, if your energy bills have skyrocketed for no apparent reason, these issues could be why:

Grimy HVAC filters. When HVAC filters become dirty, they block airflow, which forces your furnace or heat pump to work harder. This additional effort drives up energy consumption, increasing costs. Check air filters regularly, and replace them whenever they look dirty, which could be as often as every month during the winter.
Short cycling heating system. Short cycling occurs when your furnace turns on, and then switches off before your home has properly heated. Dirty air filters and the lack of airflow are a main cause of short cycling, but there are other, more complex problems that can cause a system to short cycle. If your system is short cycling and driving up your energy costs, have a professional check the problem and find a solution.
Using a heat pump when temperatures are too low. Many air source heat pumps decline in efficiency when temperatures fall below freezing. If the weather is too low outside, you may need to switch to a backup heating system, or have a professional upgrade your system to a cold climate heat pump.
Old, inefficient furnaces. Over time, furnace efficiency has become much better, lowering costs. If your heating bills are high, consider upgrading to a newer model. Consider replacing your furnace with a more efficient model if your heat pump is more than 10 years old and your conventional furnace is older than 15 years old.
Uninsulated or leaky ductwork. Ducts should be properly insulated to keep heat inside the lines. If your ducts are placed in areas prone to low temperatures, have them insulated to reduce heat loss and to lower your heating costs.
Leaky ductwork. Homes can lose as much as 30% of their heated air due to leaks in ductwork, which can cause the system to stay on for longer and drive up energy costs. Ask an HVAC contractor to check your system for leaks and to seal the properly to prevent added costs.
Incorrect thermostat programming. Double-check your thermostat to make sure your fan is set to “AUTO” and not “ON.” If systems are set to “ON,” the blower fan will continue to draw power and run, even when the system isn’t heating, which can waste energy.
Using backup heating systems. If your home is cold and you use supplemental heating, it can drive up your energy usage and costs. Only use supplemental heating when the heat pump is in the middle of a defrost cycle, temperatures are low for extended periods of time, or there is a problem with your primary heating system. If you have a heat pump, make sure your system is set to “HEAT” instead of “EMERGENCY HEAT.”

14. Furnace Producing a Burning Smell

When your furnace is switched on at the start of the season, it will burn off dust inside the unit, which can produce a slight burning odor. However, if that smell persists throughout the year, the reason may be:

Wiring issues. Electrical wiring problems within your furnace can cause the wire insulation to burn or melt, causing the burning plastic odor you smell. If you smell burning plastic and you suspect your furnace, turn off your system and request professional assistance.
Dirty HVAC filters. Dirty furnace filters can cause odors in your home to stick around, even if they aren’t coming from your furnace. Replace your filter as soon as it looks dirty, which could be as often as every month during the winter.
Motor overheating. Furnace motors that overheat create a burning smell. This problem is typically caused by airflow restrictions, so check your vents and air filters for obstructions. Worn bearings can also cause your motor to overheat. If your furnace overheats or short cycles, turn it off until a professional can assess the situation.

15. The Carbon Monoxide Detector Goes Off

Carbon monoxide detectors should be installed on every level of a home that relies on a gas furnace. If CO2 detectors sense that the level is too high, they will sound to alert occupants to the presence of carbon monoxide, which can be lifesaving. However, a CO2 system going off can indicate one of the following problems with your furnace:

Cracked heat exchanger. Heat exchangers inside your gas furnace hold combustion gases, allowing their heat to warm air passing across it. If the heat exchanger is cracked, CO2 may mix with the air moving into your home. Poor maintenance is a common cause, so check your system regularly for rust, corrosion, and damage, and have a professional inspect your system and perform a tune-up annually. Heat exchangers can be professionally replaced.
Improper installation. Furnaces rely on exhaust and venting systems to move fumes away from the system. If your furnace does not have properly installed venting, carbon monoxide can escape into your home. Only have an experienced, NATE-certified HVAC professional install new furnaces and flues to prevent this hazard. If you don’t think your venting was installed appropriately, have a professional inspect and repair it.
Blocked or damaged flue pipe. Your flue pipe moves exhaust from your furnace outdoors, where CO2 can naturally dissipate into the environment. However, if the flue pipe is blocked or damaged, this gas could enter your home. Make sure there is at least five feet of clearance between the outdoor flue pipe and other objects, including tree branches, neighboring structures, birds’ nests, or ice accumulations. Check the pipe for damage, rust, or corrosion. If you suspect issues with your flue pipe, consult with a professional.
Backdrafting can occur when furnaces draw air out of the combustion chambers or exhaust instead of pushing air through the system. Caused by depressurization within the heating system and ductwork, this problem is best resolved by a skilled professional to restore balance.

16. Dirty Air Handler or Furnace

If your furnace or air handler looks visibly dirty when you look inside, efficiency could be compromised. Here are a few issues that can cause a grimy system:

Burner carbon buildup. As your furnace combusts fuel to generate heat, soot can build up on your furnace’s burners. Dirty burners aren’t capable of completely combusting fuel, and visible soot may be present. Burners should be professionally cleaned during routine professional maintenance, but you can clean them yourself by carefully following the directions in your owner’s manual.
Dirty air filters. Air filters that are dirty or damaged can inhibit airflow and cause dust to readily pass into your system. Replace air filters whenever they look dirty, which during heavy use periods like winter, could be as often as every 30 days. Professional HVAC teams can clean the interior of your system during routine tune-ups.
Cracked heat exchanger. Excessive soot can be a sign that your heat exchanger is cracked and damaged, which can also cause carbon monoxide to enter your home. If you spot excess soot, turn off your furnace until you consult with a professional. Cracked heat exchangers can be dangerous and must be replaced.

17. Furnace Filters Clog Easily

Air filters should be replaced routinely to keep your furnace running efficiently. If air filters become clogged sooner than once a month, there could be issues with your furnace. Here are a few problems that could lead to more frequent filter clogs.

Leaks in your ductwork. If holes or gaps are present in the ducts that move heated air into your home, the pressure change can pull contaminants from areas like basements, attics, or wall interiors into your ducts and HVAC system, clogging filters. Notify a professional anytime your filters fill up fast, or if there are foreign objects like pests, insulation, or sawdust present on dirty air filters as your duct system needs work.
Dirt accumulation near return air vents. Return air vents feed indoor air back to your heating system. If there is dirt on the ground around the air vent, it could be flowing towards your filter and causing the problem. Keep air return vents and the area around them as clean as possible.
Blower fan set to “ON.” Your furnace or heat pump’s blower fan should be set to “AUTO,” and not “ON.” While the “ON” setting is appropriate when you need extra air filtration or circulation to dry recently cleaned carpet, leaving your system on this setting can circulate more air, which can fill up filters faster. Turn your system to “AUTO” to correct this problem.
High indoor contaminant levels. Indoor activities like playing with household pets, cooking, cleaning, and crafting can result in high levels of indoor pollution. When more contaminants are present, filters won’t last as long. Do what you can to reduce indoor contaminants, such as baking instead of sautéing or frying, using pourable cleaners instead of aerosol sprays, or crafting in areas that can be opened up to the outdoors, such as garages.

18. High Humidity Indoors

High humidity makes Louisville, Kentucky, and the surrounding areas lush and green during spring and summer, but in the wintertime, high moisture contents indoors can be a problem. Windows may fog or collect condensation, which can spark mold and mildew growth. Heating problems that create excess humidity include:

Humidifier problems. Humidifiers add moisture inside and make it feel warmer. However, when humidifiers are damaged, they may add too much moisture to the indoor air. Use a hygrometer in your home to make sure the reading on the device falls in line with the humidistat on your humidifier. If there are inconsistencies, have the appliance professionally inspected and repaired.
Lack of ventilation. Ventilation brings fresh, outdoor air into your space to replace moist, stale air. If your home is overly humid, more ventilation may be needed throughout your home. Talk with an HVAC professional to discuss your options.
Damaged or inadequate exhaust fans. Kitchens and bathrooms can generate a great deal of indoor odors and pollutants. Additionally, since water use is heavy in kitchens and bathrooms, they are prone to humidity accumulation. Reduce humidity levels in your home by checking the exhaust fans. If fans aren’t working or aren’t rated properly for the space, humidity can linger. Exhaust fans can be replaced relatively easily if you have experience with electrical work, or you can always enlist the help of your HVAC technician.

19. Water Pooling Around Heating Equipment

Standard furnaces do not produce condensation while running, but condensing furnaces are designed this way. Secondary heat exchangers in condensing furnaces capture more heat, giving gases time to cool and convert to water before exiting the system. However, if water is leaking from either variety of furnace, these problems could be at the root of the issue:

Humidifier leak. If you rely on a whole home humidifier to add moisture to your indoor air and you notice a water around your furnace, you could have a leak in the water supply line that is leaking onto the floor. Check the water line to see if it is dripping. If it is, have it replaced to correct the water problem.
Clogged or leaking condensate drain. Furnaces often share space with indoor air conditioner components. If you have water pooling around your HVAC equipment, it may actually stem from your air conditioning system. Damage or clogs to the condensate drain attached to your air conditioner could cause water to pool. Damage to a high-efficiency condensing furnace’s drain pump, tube, or line can also leak. Check the interior of your system to see if water seems to be exiting your system normally. If there are clogs or damage to the drip pan or condensate drain line, the area can be repaired by a professional.
Cracked secondary heat exchanger. If you have a condensing furnace, a crack to the secondary heat exchanger could allow water to escape the condensing unit and run back into the furnace instead of out the proper drain line. Heat exchanger cracks can be dangerous and should be professionally replaced to protect your family from CO2 exposure.
Damaged or incorrectly installed flue pipe. Flue pipes are designed to exhaust gases from your furnace outside where they can’t be harmful. However, if the flue is too long, sloped, or clogged, it could allow air to pool in the pipe, condense, and leak. Check your flue pipe, and the exterior of the pipe outside, to look for blockages, and clear them if possible. If the pipe is blocked, do not use your furnace until a professional can inspect and correct the problem.

20. Heating Equipment Needs Frequent Repairs Lately

While you may be accustomed to ordering repairs occasionally for appliances throughout your home, a system that needs many more repairs than it has had other years may be an indicator of a failing furnace. Here are a few reasons your heating system may require more repairs this year:

Failure to perform appropriate maintenance. Your furnace requires annual professional tune-ups to check components for damage, clean the interior of the system, and to look for critical issues, such as cracks in the heat exchanger. Filters should be replaced at regular intervals and homeowners should be on the lookout for new issues that could spell trouble. If you don’t take care of your furnace, your system may develop more emergency problems. Schedule professional tune-ups for your furnace every fall, and tune-ups for your air conditioner every spring.
New furnace needed. Like any other home appliances, furnaces have a finite lifespan. Conventional furnaces typically last between 15 and 20 years, and heat pumps last about 12 years on average. Breakdowns are much more common in the last two years of your furnace’s lifespan. Take repeated problems as a sign that you may need a new heating system soon and consult with a professional.

Preventing the Most Common Heating Problems

While many heating problems may be the result of an old, outdated system, others are easy to prevent. Professional home heating system maintenance counteracts the wear and tear your system endures as it runs throughout the winter, so you can stave off emergency system failures. Furnace tune-ups should be performed once a year, while heating pumps require two annual tune-ups, since they heat and cool your home. Fall is a great time to conduct routine maintenance, but if you missed your window, don’t worry. Having an HVAC professional come in to conduct preventative service, even during winter, can help you to prevent problems.

Order Heating Service from Jarboe’s Heating, Cooling & Plumbing

Anytime you experience any issue with your furnace, contact us here at Jarboe’s Heating, Cooling & Plumbing. Our NATE-certified technicians can conduct thorough, careful testing and troubleshooting to determine the root cause of the problem and recommend the proper repairs. We are committed to helping you regardless of the date or time, and that’s how it’s been since our inception in 1986. We offer a 100% service guarantee, so contact us today to schedule repairs or maintenance.