Here Are the Top 20 Problems Your Heating System May Experience This Winter

Williams Comfort Air - Tech working on HVAC unit

Indiana winters bring chilly temperatures and often, multiple days below freezing before the season is through. Homeowners throughout the Indianapolis area and Central Indiana region depend on the warmth produced by heating systems for both safety and comfort during the winter months.

Reliable furnaces, heat pumps, and boilers are an absolute necessity in Hoosier homes, but occasionally even the most dependable equipment experiences performance issues. Some heating system issues tend to be more common than others – homeowners who know how to identify heating problems and troubleshoot them are often able to minimize disturbances caused by heating outages, as well as the discomfort and unsafe situations that can arise when a home is without heat through periods of cold weather.

Williams Comfort Air aims to help our Central Indiana area neighbors stay safe and warm through the winter months, not only through quick heating repair service and the installation of reliable heating equipment, but also by empowering homeowners with the information they need to counteract a heating crisis at home. Our NATE-certified heating technicians explain common heating problems and what issues are likely to cause the performance problems experienced in Indianapolis area homes.

The comprehensive guide below details common heating problems as well as potential causes. Learn what to do when you experience heating system performance issues at home, whether it be troubleshooting or contacting your HVAC contractor for repairs. Learn what to expect either way, so you can take control of the situation to preserve home comfort and safety this winter.

How to Use this Guide

The heating issues identified below are grouped by common symptoms homeowners experience which are often an indication of heating system troubles. Below each symptom are possible explanations as to what may be taking place within the furnace, boiler, or heat pump to produce it, as well as what is done to correct each cause. Diving in to the symptom you experience, you’ll learn if there are troubleshooting measures that may help you resolve the issue and how to perform them, or if professional service is required and what your HVAC technician may do to correct the issue and prevent further problems.

20 Most Common Winter Heating System Problems

If you experience heating issues this winter, search this list of common heating system problems for the symptoms you notice at home. Discover the possible causes and what to do to correct issues with your furnace, heat pump, or boiler.

1. Heating system won’t turn on

A heating system that doesn’t turn on when expected can incite panic amongst homeowners. This common heating problem doesn’t necessarily mean the furnace or heat pump is bad – often, simple problems are the reason why the system doesn’t turn on. If your heating equipment does not turn on at all, potential causes are:

  • No power to thermostat. The thermostat controls all communication to the furnace or heat pump – if it doesn’t have power, it doesn’t tell the heating system to start up and heat the home. How to fix thermostat power issues includes replacing batteries and verifying tight electrical connections, as well as verifying power supply at the home’s electrical panel for hardwired thermostats.
  • No power to heating equipment. If there is no electricity going to the heating system, its components will not activate even when the thermostat instructs them to do so. A tripped breaker or flipped external power switch on the furnace, air handler, or outdoor heat pump may be the reason why.
  • Improper thermostat settings. Simple thermostat errors prevent heating equipment from starting when expected. Make sure the HEAT setting is selected and verify any programmed temperature adjustments are correct.
  • Loose access door. If the door to the furnace or air handler’s blower compartment is loose or not properly closed, this may prevent the system from starting when instructed. Some models are equipped with this safety feature to prevent accidents and damage to blower components.

2. Poor or no airflow from heating vents

Airflow issues can be attributed to a number of causes, some easily solvable while others require professional repair service.

  • Closed vent louvers. Some vent covers have louvers which open and close to control airflow from the vent. If these louvers are mistakenly closed or become stuck in a closed or partially closed position, airflow into the room is restricted and the space may not receive adequate heating. Check the position of the vent louvers and make adjustments to solve this issue. When louvers become stuck, it is sometimes possible to repair them. Replacing the vent cover corrects this issue when closed louvers are damaged beyond repair.
  • Duct leaks. Duct leaks prevent the proper amount of heated air from reaching the room, instead allowing it to escape elsewhere in the home. It is possible to assess the ducts for leaks and make repairs if they are accessible. Professional duct sealing methods provide more reliable repairs and correct issues impacting inaccessible ducts.
  • Ductwork obstructions. If a duct run is obstructed, the proper volume of heated air will not reach its intended destination. Ducts may become obstructed due to damage or disconnections. If you are able to access the duct, it is possible to identify an obstruction and repairs may also be possible, depending on the issue. Your HVAC technician is also able to assess for ductwork obstructions and make durable repairs.
  • Furnace filter issues. Dirty air filters restrict air movement through the heating system, which can result in a lack of airflow from room vents. Typically, this issue is easily solved by replacing the filter, or cleaning it if a reusable filter is installed. Improperly installed filters can also restrict air movement – the size of the filter should be verified to ensure the appropriate filter size is in use, as well as the direction in which the filter is installed. The use of certain high efficiency filters may also restrict airflow to the point you feel a lack of air from room vents.
  • Blower motor malfunction. The blower motor is the component responsible for moving heated air through the ducts and into rooms throughout the home. Malfunctions of the blower motor than impede airflow include a buildup of dirt and grime on the fan, a loose or broken fan belt, faulty fan belt pulley, worn out motor bearings, faulty capacitor in the motor, or a lack of electrical power to the component. Furnace troubleshooting for this issue may be possible by DIY, while others require the assistance of a professional. Replacement of the blower motor unit is a possible solution, depending on the issue at hand.
  • Damper malfunctions. Automatic or manual damper valves are installed in the duct system to regulate airflow throughout the home. When a damper louver becomes stuck in a closed or partially closed position, airflow is restricted. If accessible, it may be possible to free up a manual damper valve yourself. Automatic dampers are controlled by the thermostat, so stuck dampers indicate a communication issue which requires professional diagnosis – repair or replacement of the damper and/or the thermostat may be necessary.
  • Not enough return air vents. A home’s duct system is carefully designed to balance the return of air from the interiors back to the heating system. Too few return air inlet vents cause low airflow from room vents due to pressurization – how to fix this airflow issue requires the assistance of an experienced HVAC professional.

3. Cool air comes out of the vents when furnace runs

Does it seem like your heater tries to come on, but never fully gets there? Does it sound like the system is running but there’s no heat coming into your home? The surprise of cold air coming through room vents as the heating system runs can be caused by several different HVAC issues:

  • Incorrect blower fan settings. If cool air comes from the vents, it could be due to a constantly running blower fan. Using the ON setting keeps the fan on all the time rather than only during heating cycles – when the heating system does not run, the fan blows cool, unheated air through vents into rooms. Using the AUTO setting avoids this issue.
  • Dirty furnace filter. Clogged air filters prevent proper airflow through the heating system, which may cause the heating system to overheat. While elements of the furnace or heat pump that produce heat shut down, the blower may still operate, moving cool air into rooms.
  • Lack of heating fuel. Furnaces often use natural gas, liquid propane, or heating oil as fuel for combustion. If fuel reserves are empty or utility gas service has been disrupted, the furnace may come on but combustion will not occur, therefore no heat is generated. Refilling fuel storage can correct this issue for liquid propane or heating oil furnaces. Utility outages or damage to gas lines may need to be investigated for natural gas furnace models.
  • Closed gas valve. A closed gas valve prevents fuel from moving to the ignition system, so the furnace is unable to combust fuel to produce heat. The blower motor may still run, but only cool air comes from the vent because no heat is made. Gas valve position can be adjusted and faulty gas valves replaced if the valve is stuck in the closed position.
  • Faulty ignition. If the ignition system fails to initiate, no flame is produced in the burners to combust heating fuel. Ignition issues have many potential causes, from an unlit pilot light to malfunctioning ignition components, which are detailed in the section below. How to fix a faulty ignition may be possible through do it yourself steps or require professional HVAC repairs.
  • Significant duct leaks. Significant duct leaks allow a large volume of heated air to escape the ducts while allowing the infiltration of cold air from the surrounding unconditioned spaces. If the furnace runs a heating cycle properly but rooms receive cold air, drastic heat loss through ducts may be at fault.
  • Condensate line clog. In high efficiency condensing furnaces, blockages in the condensate drain line can disrupt system ignition. Clogs or incorrect drainage due to damaged components can cause the furnace’s pressure switch to open as it detects the accumulation of condensate. Proper drainage must be restored and excess condensate removed before the furnace will properly ignite. This issue is often intermittent, as condensate drains and builds back up within the system.

4. Heating system does not ignite

When the thermostat is properly powered and correctly set, the furnace should activate once the set temperature is reached. The thermostat triggers the furnace’s ignition system, which ignites the burners to start the heating process. If the furnace doesn’t ignite, the home receives no heat.

  • Pilot light is out. Furnaces over 10 years old are often equipped with standing pilot ignition systems, which utilize a constant-burning pilot light. If the pilot light goes out, heating fuel is not ignited. The furnace’s owner’s manual typically includes instructions for relighting the pilot light. However, if the pilot continues to go out, check for nearby drafts – if no drafts are to blame for extinguishing the pilot, the cause may be a faulty thermocouple, which may be corrected through cleaning of the component or replacement. A bad gas regulator could be causing fuel supply issues with multiple gas appliances in the home – contact your utility provider for immediate assistance.
  • Electronic ignition is dirty. Accumulation of carbon on electronic ignitors can prevent proper ignition of the furnace. A repetitive clicking noise usually occurs, which indicates the ignitor is not working correctly. Careful cleaning is needed to remove carbon while protecting this fragile component.
  • Cracked hot surface ignitor element. If the hot surface ignitor’s heating element has cracked, the furnace will not ignite. Typically, this component has a service life of three to five years and requires periodic replacement, though it may fail sooner when exposed to improper handling or short cycling. Careful homeowners may be able to replace this component, or an HVAC technician can be called on to complete the task.
  • Damaged ignitor. Ignitors sustain damage due to wear and tear, occasionally requiring replacement. To diagnose a damaged ignitor, a multimeter is used. Depending on the type of ignitor and ignition system, replacement may be a complex task and should be left to a professional.
  • Wrong ignitor installed. Improper furnace installation can lead to the wrong type of ignitor being put into use. An ignitor that requires incorrect voltage can cause the ignition system to fail. Furnace troubleshooting includes replacing the component with the proper part for the furnace’s ignition.
  • Malfunctioning limit switch. When operating normally, the limit switch shuts off the ignitor when the furnace reaches high temperatures. If the limit switch malfunctions, it may unnecessarily impede ignition. Poor airflow and dirty filters may also cause the ignition to be shut down prematurely by the limit switch – replacing filters can prevent this issue and correct overheating. If the limit switch is damaged, it needs to be replaced.

5. Furnace filter becomes clogged faster than usual

Air filters need to be replaced on a regular basis, as filters become clogged with contaminants pulled from circulating air. It is normal for filters to require more frequent replacement during the winter months due to increased heating system operation – however, abnormal issues may cause your filter to become clogged sooner, requiring replacement much earlier than expected.

  • Blower fan is set to ON. When the fan is set to ON at the thermostat, the blower runs continuously. As air constantly circulates through the HVAC system, it completes more passes through the filter, and the filter fills with contaminants at a faster rate. Turning the fan to AUTO is a furnace troubleshooting step that can help filters last longer.
  • Duct leaks. Duct leaks allow more contaminants into the indoor air supply from the unconditioned areas surrounding the ductwork. With more contaminants in the air, the filter will fill faster as air circulates.
  • Dirt accumulation near return air vents. The home’s return air vents feed indoor air back to the heating system for conditioning. Accumulation of dirt on or around the return air vent introduces more contaminants to the air supply and forces the filter to fill at a faster rate in order to keep them out of the heating system.
  • High levels of indoor contaminants. High levels of indoor air pollutants create a bigger burden for furnace filters and they become clogged much faster. Filters typically don’t last as long in homes with indoor pets or where indoor smoking takes place. Weatherizing the home to prevent winter heat loss traps contaminants indoors, which can increase concentrations of indoor air contaminants.

6. Thermostat doesn’t turn on / thermostat screen is blank

The thermostat controls the home’s heating system – if it does not turn on, you have no way to communicate the need for heating to your furnace, heat pump, or boiler. Reasons the thermostat may not turn on include:

  • Incorrect thermostat settings. If the thermostat has been turned off, its display will be blank. Thermostats should be left on throughout the year rather than turned off, but accidental adjustments are possible. Verify this setting and ensure the thermostat itself is on.
  • Dead batteries. If the batteries die, the thermostat cannot turn on or control the heating unit. Replacing existing batteries with fresh replacements will power the thermostat and allow it to turn on if this is the source of the issue.
  • No electrical power. Some thermostats are hardwired and powered by the home’s electrical system. A tripped breaker or blown fuse in the electrical panel may prevent the thermostat from receiving power. Resetting the breaker or replacing the fuse corrects this issue.
  • Loose wiring. If thermostat wiring becomes loose, its operation may be disrupted. An HVAC technician is able to identify issues with wiring and electrical connections within the thermostat. Sometimes these issues are repairable, while other times it may be necessary to replace the thermostat.
  • Loose furnace access panel. Some thermostats appear to shut off entirely when access panels on the furnace are loose or not securely shut – Honeywell thermostats in particular are known for this safety measure. Examining the panels of the furnace and ensuring each is properly closed and affixed to the unit can eliminate this issue.
  • Tripped float switch. Newer condensing furnace models typically include a float switch that is linked to the thermostat. This safety control detects high moisture in the heating equipment to help prevent moisture damage and alert homeowners to malfunctions of the system’s condensate drain components. When the float switch is triggered by moisture, power to the thermostat is cut. Resetting the float switch and verifying proper condition and operation of drainage components clears up this issue.
  • Heating system overheats. If the thermostat’s display goes blank in the middle of a heating cycle, it is possible that the furnace has overheated. High internal temperatures trigger the system’s limit switch, which halts furnace operation and can affect the thermostat display as well. Overheating is often caused by dirty filters or blocked vents.
  • Faulty thermostat. If none of the issues described above are the source of a blank thermostat, it’s time to replace the unit. Most thermostats last about 10 years, though it’s not uncommon to see very old models still in use. Install a new thermostat yourself or have it done by your trusted HVAC professional.

7. Changing the thermostat’s temperature doesn’t do anything

When you adjust the thermostat’s settings, you expect the heating system to respond accordingly. If changing the temperature on your thermostat doesn’t produce results, the issue may be:

  • Lack of power to heating equipment. A tripped breaker or blown fuse prevents the heating equipment’s circuit from receiving power – the heating equipment will not come on, despite the thermostat’s calls. Reset breakers and replace fuses on circuits powering indoor heating equipment, as well as outdoor equipment in heat pump systems. Heating systems also have ON/OFF switches for the equipment located on or nearby the units – if the switch is mistakenly or accidentally turned off, the equipment cannot run. Verify and adjust switch position if needed.
  • Thermostat is locked. Digital thermostats often include a lock function which prevents adjustments when activated. If the thermostat is locked, follow the owner’s manual instructions to unlock the device before making temperature adjustments.
  • Thermostat is set to AUTO. Some thermostats have automatic operation modes. When auto mode is activated, the thermostat runs using programmed temperature setpoints and cannot be adjusted. Switch the thermostat’s mode back to HEAT in order to adjust temperatures.
  • Thermostat wiring problems. Dirt accumulation on wiring within the thermostat as well as loose electrical connections and corroded wires can prevent the thermostat’s communication with the home’s heating equipment, making temperature adjustments useless. Careful cleaning of the internal wires, tightening of wiring connections, and replacement of corroded wires can restore communication.
  • Improper thermostat location. Where the thermostat is installed is critical to its operation and performance. It needs to be placed in a neutral location away from sources of heat or drafts, or else its sensors may misread room temperatures. When incorrect temperatures are read by the thermostat, adjustments to its settings may not produce effects. Relocating a thermostat should be done by an HVAC technician.
  • Unlevel thermostat. Improper positioning of the thermostat can also impact its ability to correctly read the room temperature – an unlevel unit or thermostat that is mounted on a wall with an uneven surface prevents a good pin connection between the thermostat and its backplate. Adjust thermostat positioning to ensure accurate temperature sensing and control of home heating.

8. Heat pump doesn’t heat home

Some Central Indiana homes use heat pumps as a primary heating source during the winter. If it feels like the heat pump isn’t heating your home, one of these common heat pump problems is likely to blame:

  • Incorrect blower fan settings. If the blower fan is set to ON at the thermostat, it runs all the time, even when the heat pump isn’t producing heat. This mistake often causes homeowners to believe the heating unit is running all the time. A simple adjustment of the fan settings puts an end to this problem.
  • Incorrect thermostat settings. If the thermostat is set to COOL or OFF, the heat pump does not produce heat. Accidental adjustments are often to blame when this is the case, and simply resetting the thermostat restores heating.
  • Dirty air filter. A dirty filter prevents good airflow through the system, hindering its heating process. Air filters need to be replaced regularly, and often more frequently during winter months due to heavier system usage.
  • Refrigerant leak. Refrigerant leaks cause the heat pump to lose its proper refrigerant charge, robbing the system of its ability to heat the home. An HVAC technician must inspect and repair damaged refrigerant lines as well as recharge the system – this cannot be done by the average homeowner, as EPA certification is required for handling refrigerant.
  • Stuck reversing valve. The reversing valve switches the system from cooling to heating mode, and vice versa. If it is stuck, the system will not reverse and continue to cool the home rather than heat it. Replacement of the component is necessary.
  • Blockage of outdoor unit. To heat, heat pumps extract heat from the outdoor air. If the outdoor unit is blocked by leaves, snow, or ice, efficient heating is prevented. These debris can typically be easily cleared to remedy the problem.
  • Defrost cycle. Heat pumps regularly run a built-in defrost cycle during the winter to melt away ice accumulation on the outdoor unit. While this cycle runs, the heat pump operates in cooling mode to heat the outdoor coil. Typically, the backup heating system will operate to heat the home as the heat pump defrosts, but a broken temperature sensor, reversing valve, or backup heating unit may cause a lack of heat for this period.
  • Heat pump is iced over. The heat pump’s defrost cycle may not have the power to melt away heavy ice accumulation, and the ice blocks the system from heating the home. How to fix an iced over heat pump may be as simple as clearing blockages of the outdoor unit or redirecting leaky gutters overheat, or require professional help for the replacement of faulty components.
  • Faulty starting components. If the heat pump does not turn on, its starting capacitor may be bad, which prevents the motor from receiving electrical power. This issue sometimes produces a slight clicking noise at startup. The capacitor needs to be professionally replaced.
  • Outdoor temperatures are too cold. Heat pumps can offer energy efficient heating, but in certain conditions, their efficiency declines. When outdoor temperatures fall below about 25 degrees Fahrenheit, some heat pump models struggle to adequately and efficiently heat the home. Supplemental electric resistance heat strips or backup gas heating systems can be installed to take over when outdoor temperatures drop too low and provide more efficient heating during these periods.

9. Certain rooms are difficult to heat, home has cold spots

When the home has areas that are hard to keep comfortable, where some rooms are colder than others, the HVAC system is unbalanced. This means each area is not receiving the proper amount of heating necessary to maintain even temperatures across the home.

  • Dirty air filters. Clogged air filters make it more difficult for air to flow through the system, so some areas of the home may not receive adequate heating. Replace it to eliminate cold spots caused by dirty furnace filters.
  • Closed room vents. Room vents are often unknowingly blocked by rugs, carpets, furniture, and other household items, especially in homes where vents are positioned on the floor. Louvers in certain register models can be closed and forgotten or become stuck in the shut position. These issues prevent the correct amount of heat from reaching the area served by that supply duct. Whenever you notice cold spots or difficulty heating a space, the room vents should be inspected for obstructions.
  • Duct leaks. Duct leaks allow heat to escape, so a lesser volume of heated air is delivered to the room. Leaks are caused by damage, loose joints, and even collapsed duct runs. Duct leak inspection and repairs can sometimes be done effectively at home, but in difficult-to-access areas, it’s a job best left to your HVAC technician.
  • Duct obstructions. Blockages within the ducts also restrict the flow of heated air into the living areas served by that supply duct run. Obstructions can result from collapsed ductwork or items that have fallen into the floor vent. Collapsed ducts are damaged and should be replaced. It may be possible to retrieve items that have fallen into the duct, depending on their location – or, have your technician do it to ensure your ducts aren’t damaged in the process.
  • Stuck dampers. Duct damper valves regulate airflow through the duct system, opening and closing to control the amount of heat moving to each area of the home. If a damper is stuck closed, heat is cut off from the areas served by the duct. Manual dampers may be adjustable, while automatic dampers are controlled by the thermostat and require a professional to correct the communication issue that has caused the malfunction.
  • Uninsulated ducts. Ducts commonly run through uninsulated areas of the home, and the warm air traveling within can lose heat as the sheet metal ducts become cold due to low surrounding temperatures. If ducts aren’t insulated, areas of the home farthest away from the furnace or heat pump are typically the most difficult to adequately heat, as more heat is lost due to air traveling a longer distance of ducting.
  • Poor duct system design. If the home’s current ducts are incorrectly sized, rooms don’t receive adequate airflow. Have your duct system professionally inspected and replaced if needed.
  • Thermostat location. A thermostat detects surrounding temperatures to signal the heating system when it is necessary to turn on and shut off heating. Most homes have one thermostat to control temperatures throughout all levels – the thermostat may sense the air immediately surrounding the device has reached the correct temperature and shut down the heating cycle, though other areas have not received enough heating. Installation of a zoning system provides each area with its own thermostat for individualized control over heating.
  • Blower fan speeds. If your furnace or air handler has a multi-speed or variable speed blower motor, fan speed may need to be adjusted to deliver adequate heat and balance air throughout the system. The equipment owner’s manual may include instructions for making this adjustment, but your HVAC technician can also perform this task.
  • Heating system short cycling. If the furnace or heat pump system short cycles, heating cycles do not run long enough to adequately heat the home. This issue can be caused by airflow obstructions, oversized heating equipment, or faulty components. Some of these issues can be repaired, though the only fix for an oversized HVAC system is to replace it.
  • Old heating system. Older heating units often have trouble providing adequate heat throughout the home. If you now experience cold spots and rooms that are difficult to heat but no other causes explain the issue, it could be that your furnace or heat pump is at the end of its service life and should be replaced.
  • Undersized heating system. A heating system that isn’t large enough for the home will struggle to adequately heat living areas. Unfortunately, the only way to fix this issue is to replace the existing unit with a new system that is the appropriate capacity.
  • Oversized heating system. A furnace that is too big heats air quickly – areas near the furnace will be warmed rapidly and the thermostat shuts off the heating cycle too soon. Areas farther away from the furnace are left without enough heat. This problem is corrected by replacing the furnace with an accurately sized HVAC unit.
  • Inadequate insulation. If insulation levels are lacking, rooms may lose heat produced by the heating system. Installing new insulation as well as duct insulation can help you combat this issue.
  • You live in a multi-level home. Multi-level homes are notoriously hard to evenly heat – because heat rises, the upper levels are often much warmer than lower levels. Having a zoning system installed to work with your HVAC system is an excellent way to even out temperatures throughout the home.

10. Heating system shuts off shortly after coming on

Heating equipment typically cycles for 10 to 15 minutes at a time. When the system starts up and shuts down again within a minute or two, this issue is known as short cycling. Short cycling has many causes – despite its cause, this issue causes damage to the HVAC equipment along with discomfort in the home, leading to higher heating bills and more frequent system repair needs.

  • Thermostat malfunction. Faulty electrical connections, dirty temperature sensors, improper location of the device, or even an unlevel older mercury model are all issues that cause short cycling stemming from the thermostat. Gentle cleaning of sensors, recalibration, repositioning, or replacement may be used to solve these issues.
  • Improper thermostat anticipator calibration. Some older manual thermostats have adjustable heat anticipators which warms up the interior of the thermostat in order to prematurely end a heating cycle. This is done in anticipation of residual heat in the ducts, allowing it to reach the living areas while avoiding overheating the space. Improper calibration of the anticipator can end heat cycles too early, causing short cycling. They can be adjusted, or the entire thermostat can be upgraded.
  • Overheating caused by poor airflow. Dirty air filters and closed room vents restrict airflow through the furnace, which causes interior components to overheat. The furnace’s limit switch shuts down operation when internal temperatures are too high for safe operation. Replace the furnace filter and check all room vents to ensure they are fully open. A blocked flue pipe can also cause furnace overheating – blockages must be found and cleared not only to prevent short cycling, but possible carbon monoxide exposure in the home.
  • Faulty flame sensor in furnace. The flame sensor detects the presence of a flame when the furnace’s gas valve is open, working to prevent dangerous gas leaks and explosions. When it becomes dirty from soot, it may not detect the flame and the system shuts down shortly after starting as a safety measure. The existing sensor can be cleaned or replaced if broken, as corrosion is a common cause of damage to this component.
  • Faulty furnace draft inducer motor. Many newer furnaces feature a draft inducer motor that exhausts combustion gases leftover from the prior heating cycle. If its air pressure switch does not detect proper airflow through the heat exchanger, it shuts the furnace down as a safety measure. This malfunction may be caused by an obstructed flue pipe, or a fault in the pressure switch or the motor itself.
  • Oversized heating equipment. When a heating system is installed that is too big for the home, it produces larger amounts of heat fast – this is not a good thing. Air heats up quickly, and the thermostat shuts down the heating cycle once the set temperature is detected. Repetitive short cycles wear out components, leading to higher energy consumption and more equipment breakdowns. Replacement is the only solution.

11. Heating system won’t shut off

If it seems like your furnace or heat pump stays on all the time, the likely causes of this common heating issue are:

  • Improper fan settings. When the fan setting on the thermostat is set to ON, the blower motor runs constantly. This issue often makes it sound and feel like the heating system runs continuously, but in reality, it’s only the blower running around the clock. Set the fan to auto so it only cycles when the heating system does.
  • Faulty thermostat. Faulty thermostats do not correctly communicate to the heating equipment, which may cause the furnace or heat pump to endlessly run. The wiring may need tightened or replaced, or the thermostat may need to be replaced if the malfunction cannot be corrected.
  • Faulty limit switch. The limit switch may be stuck, causing the blower to continuously run. Resetting the switch may solve the issue, or the component may need to be replaced.
  • Faulty compressor contractor. If the heat pump’s compressor contractor is faulty, electricity to the heat pump is not regulated. The heat pump could receive constant power and continue to run around the clock. This component must be professionally replaced.

12. Heating bills are higher than usual

Heating bills may rise this year due to a number of different causes, including drafts and air leaks at doors and windows, colder temperatures than usual, and heating system issues. Reasons why your heating equipment may be driving up your energy bills this season include:

  • Running a heat pump in freezing temperatures. Air-source heat pumps provide very efficient heating when outdoor temperatures are above freezing. Below 32 degrees, some models may not work as efficiently and using a backup heating source is best. Consider having a backup heating system installed, such as electric heat strips or forced air furnace, or consider upgrading your system to a specialized cold climate heat pump.
  • Running backup or emergency heating system. The heat pump’s backup heating system (also called emergency or auxiliary heat) is only intended for use during periods where outdoor temperatures are too low for efficient heat pump operation, during the heat pump’s defrost cycle, or if there is a problem with your heat pump. These systems are only meant for temporary use – leaving them on for longer periods results in increased energy use and higher utility bills. Always check your thermostat to make sure HEAT mode is selected instead of EMERGENCY HEAT for everyday use.
  • Heating system is short cycling. When the heating system short cycles (heating cycles start, then quickly stop), more energy is consumed running more frequent, shorter cycles. Components also experience more wear, causing inefficiency. Short cycling has a number of potential causes, from dirty air filters to improperly sized HVAC equipment – some are repairable while others require system replacement.
  • Inefficient heating equipment. Older heating equipment offers lower energy efficiencies compared to newer models, due to both higher standards for newly manufactured equipment and lost efficiency over years of operation. If inefficient equipment is the cause of high energy bills, talk to your technician about retrofit and upgrade options.
  • Uninsulated ductwork. The areas where your ducts are installed typically aren’t conditioned and may be lacking in insulation. These areas can be very chilly in the winter, making the metal ducts quite cold. Heated air moving through the duct system makes contact with the cold metal ducts, causing heat loss. Insulating ducts in unconditioned areas and improving insulation levels in these spaces can help conditioned air retain more of its heat.
  • Leaky ductwork. The average home loses 20 to 30 percent of conditioned air through duct leaks, causing unnecessary energy waste and higher heating bills. Seal duct leaks using foil tape or mastic sealant, or choose professional duct sealing services performed by your HVAC contractor.
  • Improperly programmed thermostat settings. Programmable thermostats can be excellent helpers when it comes to saving energy, but if they aren’t set right, you may be wasting heat instead of conserving it. Always double-check your temperature schedules and readjust with each season or change in daily household schedule. Make sure the fan is set to AUTO instead of ON.
  • Dirty air filters. Dirty filters restrict airflow, which makes the furnace or air handler consume more energy to circulate air through the system. Change filters on a regular basis. Check them monthly during the winter to determine if earlier replacement is needed due to higher heating system use.

13. There’s a burning smell coming from the heating unit

It’s normal for a furnace to produce a burning odor the first time you turn it on for the season – it’s just the smell of dust burning off system components. If that smell persists past the first few hours of heating use, the reason may be:

  • Dirty furnace filter. A dirty filter may cause the odor to linger. Replacing the filter should eliminate the issue if this is the cause.
  • Wiring problems. Wiring issues within the furnace may cause wiring insulation to burn or melt, producing the smell of burning plastic. The system needs to be shut off and inspected by a professional so repairs can be made before further use.
  • Overheated motor. If a motor within the furnace is overheating, it may also produce a burning smell. This issue is typically caused by airflow restrictions, so filters and vents need to be checked. Worn bearings can also cause the motor to seize and overheat. System use should be stopped until repairs can be made by a professional.

14. Water on the floor near heating equipment

Conventional furnaces do not normally produce condensation during operation; condensing furnaces do, as their secondary heat exchanger captures more heat from exhaust gases, giving the gases time to cool and convert to water before exiting the system. Water leaks are top furnace problems affecting condensing models but can also occur in conventional units. Mold growth in the heating system or ducts can result from leaks.

  • Clogged condensate drain in condensing furnace. Damage or clogs in the furnace’s drain pump, tube, or line can lead to water leaks. Clogs may be removed and components replaced to stop the leak.
  • Faulty flue pipe in conventional furnace. Poor flue design or faulty installation of the flue pipe can cause exhaust gases to remain in the pipe long enough to convert into water. This occurs when the flue is too long, too big, sloped, or clogged. The resulting condensation leaks back into the furnace and out on the ground around it.
  • Cracked secondary heat exchanger. A crack in the secondary heat exchanger of a condensing furnace can allow water to escape and run back into the furnace instead of out the drain line.
  • Humidifier leak. If your HVAC system has a whole home humidifier that is used during the winter months, a leak in this component could be to blame for pooling water near the heating equipment. These units have dedicated water supply lines – when they are clogged or damaged, water may leak. Problem areas may be found in the supply line, drain line, or external casing.
  • Leaking air conditioner condensate drain. If there is water on the floor near your furnace during the spring, summer, or fall while the air conditioner operates, the leak may actually be from your cooling equipment. If the heating and cooling equipment share a cabinet or are connected indoors, it may look like the water comes from the furnace when it’s really condensation produced through cooling which is not correctly draining from the air conditioner. Clogs or damage to the drip pan or condensate drain line are typically to blame.

15. The carbon monoxide detector goes off

Carbon monoxide detectors should be installed in every home that uses a gas furnace. When carbon monoxide (CO) levels rise too high, the detector alerts everyone in the home to the presence of CO so the home can be evacuated to prevent potentially deadly exposure. While high CO levels have several potential causes, some issues with your heating system that can cause the alarm to sound include:

  • Improper installation. If your furnace’s venting system and flue were not properly installed, issues may be present that allow carbon monoxide to escape the system and build up in your home. Always work with a trusted HVAC professional when installing a new furnace. If you suspect improper installation, call a trusted heating contractor to inspect your system before further use.
  • Cracked heat exchanger. The heat exchanger of a gas furnace holds in combustion gases, allowing their heat to be used for heating air that passes over the component. Cracks in the heat exchanger allow gases including carbon monoxide to escape and mix with the air circulating into the home, which can cause indoor carbon monoxide levels to rise. This issue is often caused by poor maintenance. Inspect the heat exchanger for damage, rust, and corrosion. If you suspect a crack to the heat exchanger, shut off the furnace immediately and call your HVAC technician to replace the heat exchanger.
  • Blocked or damaged flue pipe. Combustion exhaust gases are supposed to safely exit the home through the flue of a conventional furnace. If the flue pipe is blocked or damaged, these gases may back up into the home. Inspect the pipe for damage, rust, and corrosion. Check the exit point on your roof or on the outside wall of the house near the furnace’s interior location – animal nests, pests, ice, and other materials can block the flue. At least five feet of clearance should be maintained surrounding the flue pipe.
  • Backdrafting occurs when the furnace draws air out of its combustion chambers or exhaust instead of pushing air through it, causing combustion gases to enter the indoor air supply. It’s often caused by depressurization of air within the heating system and ducts. A skilled professional needs to investigate and correct issues to achieve proper air balance.

16. Heating system makes a lot of noise as it runs

Forced air heating systems like furnaces and heat pumps produce some operating noise, but it’s easy to notice when they run louder than normal or if new noises are present. Some issues that cause noisy operation include:

  • Unlubricated motor bearings. Without adequate lubrication, motor bearings will grind and make noise as the system operates. These parts need oiling each year to prevent wear.
  • Fan belt issues. If the belt connecting the fan and the motor has slipped, you may hear a squealing noise from the system. The belt may need to be tightened or replaced.
  • Loose panel. If access panels on the furnace or air handler are not properly attached, they may rattle as the system runs. Typically, these panels just need to be repositioned for a secure fit.
  • Delayed ignition. If the noise only occurs as the furnace starts up, delayed ignition could be the cause. Faulty ignition systems do not burn fuel right away – regular carbon buildup clogs the burners causing fuel to accumulate in the burner chamber and the large volume ignites at once, producing the noise. The furnace needs to be inspected and the ignition issue corrected by an HVAC technician.

17. Your heating equipment needs more frequent repairs this year

Does it feel like you’re seeing more of your furnace or heat pump repair technician this year, as compared to previous winters? Reasons why your heating system may need more repairs than usual include:

  • Poor maintenance. Professional heating tune ups address wear and tear as well as performance issues of furnace and heat pump components to help prevent the possibility of malfunctions during the winter season. These tune ups are needed each year – skipping yours could be the reason your furnace breaks down more often now.
  • Need for replacement. Furnaces typically last 15 to 20 years; heat pumps average about 12 years of service. Breakdowns are more common and occur more frequently in the last two years of the system’s service life. More calls for heating repair are a clear warning sign that your furnace or heat pump needs to be replaced. Take this warning to heart and replace the system soon to avoid a complete breakdown that leaves your household stuck without heat when it’s needed most.

18. Furnace or air handling equipment is dirty

Does your furnace or air handler equipment appear extra dirty when you take a peek inside? This can be a sign of issues present within the heating system, including:

  • Filter problems. A dirty air filter is no longer efficient at removing dust and dirt from the air supply. Instead, these contaminants are able to pass through the system and may settle throughout the interior of your furnace or air handler. This buildup leads to poor efficiency and potentially damages sensitive heating system components. Change filters regularly and have your heating equipment professionally maintained each heating season.
  • Carbon buildup on burners. Over time, carbon can build up on the furnace’s burners, causing a dirty appearance as well as clogs that can lead to incomplete combustion of fuel. Visible soot as well as yellow burner flame indicate dirty burners. Burners are cleaned during professional maintenance, but you may choose to clean them yourself if necessary throughout the year.
  • Cracked heat exchanger. Excessive soot inside your furnace can be a sign of a cracked heat exchanger. Cracks allow soot to escape the exhaust system into the furnace’s interiors. Have your system inspected by a professional right away to diagnose this potentially dangerous issue – cracked heat exchangers must be replaced.

19. Moisture problems in the home over the winter months

The winter air in Indianapolis is typically quite dry, which often creates dry air issues inside homes – too much moisture indoors during these months is certainly a cause for concern. Windows fog and collect condensation, but these issues are really the least of your worries, as too much moisture can cause mold growth in the HVAC equipment and in the home, while also diminishing indoor air quality. Top heating problems contributing to wintertime moisture issues indoors include:

  • Poor ventilation. If your heating system doesn’t have the capacity to properly ventilate your home, your interiors don’t receive enough fresh, outdoor air to replace the moist, stale indoor air. Added ventilation may be needed, which should be installed by an HVAC professional.
  • Lack of exhaust fans. Kitchens and bathrooms should be equipped with exhaust fans to quickly expel moist air created by showers, washing, and cooking. If your home does not have this equipment in place, these activities add moisture to the air and there’s no effective means to remove it, leading to increased humidity indoors.
  • Humidifier malfunction. Typically, humidifiers are used during the winter to add moisture to the indoor environment when it is naturally lacking. Malfunctions with the system’s humidistat could cause the whole home humidifier to add more moisture than needed to the air, causing high humidity indoors.

20. Thermostat displays a warning or service notification

Some newer models of programmable and smart thermostats monitor HVAC system performance and display alerts when service is needed.

Thermostat alerts are highly specific to each thermostat model, as different brands and models are programmed to alert you of different performance issues. Filter change reminders are common, and certain thermostats give indications if systems show differing trends in operation, temperature control, and other metrics which could indicate equipment problems. If you receive a thermostat alert and do not know why, it’s best to consult your thermostat manual for explanation and contact your HVAC technician for assistance if you are unable to determine or address the issue yourself.

Preventing Common Heating Problems

Certain heating problems may be inevitable and happen suddenly, but most are the result of a steady decline over time. Wear and tear develop through normal system operation, and certain issues can be worsened as the HVAC system continues to run. To avoid these issues, it’s important to keep your furnace or heat pump properly maintained each year.

Professional heating system maintenance counteracts wear and tear damage while identifying system troubles so they can be corrected before small issues progress into a breakdown. A furnace tune up should be performed once per year, while heat pumps need two annual tune ups as they function as both heating and cooling systems. Fall is the ideal time for this service, to help correct issues before the need to use the system when temperatures drop – though a tune up is beneficial at any point in the year.

Get Heating Help from Williams Comfort Air

If you experience any of these common heating problems in your Indianapolis area home, call Williams Comfort Air for quick, reliable furnace repair and heating system service. Schedule your heating tune up to have our NATE-certified technicians perform the thorough care your system needs for top performance and energy efficiency.

Schedule repairs or maintenance service for your heating system when you contact us today!

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