Furnace Troubleshooting: Common Heating Problems & Repairs

by | Dec 15, 2023 | HVAC, Heating

If your home heating system isn’t running, you don’t have the time to wade through a bunch of HVAC jargon. In the following, we will break down common heating problems that can cause it to shut down — in addition to turning off and on, to affect its heating output. 

During Ohio’s cold winter months, home heating systems help ensure your comfort and safety. But what can you do when your home heating system isn’t adequately heating your home on a cold winter’s day?  

Although you can always call an HVAC service technician, sometimes you may have to wait a few days or more. Even if you bundle up in the meantime, cold weather can still cause problems for your family and your home. 

At Five Star Home Services, we get hundreds of service calls for furnaces each week during the winter months. So, in case you’re waiting for your service appointment, we can go through some common issues that can impact your furnace’s ability to heat your home. 

Although you’ll see many articles on furnace troubleshooting that focus on jargon-heavy issues requiring a thorough understanding of HVAC — this isn’t one of those articles. 

Instead, we will be focusing on common factors that cause heating problems you can recognize just by living in your home. 

This article may be able to help if: 

  • Your furnace isn’t running 
  • Your furnace isn’t generating adequate heat 
  • Your furnace keeps turning on and off without running a full cycle 

In certain cases, you may be able to address these issues without the help of an HVAC service technician. Now we will go through these in more depth.  

Your Furnace Isn’t Generating Enough Heat

If your furnace is running but it isn’t generating enough heat, there may be an issue with airflow. 

This is a major problem because the main job of HVAC equipment is to move air throughout your home. When there’s an issue with airflow, you might notice a significant temperature difference. Nevertheless, reduced airflow can damage your HVAC equipment if it isn’t addressed quickly. 

Common types of problems that can affect your furnace’s performance:  

  • Undersized furnace  
  • Supply register issues 
  • Dirty furnace filter 
  • Air duct dampers 

The good news is that many of these issues are fairly minor at this stage. You can even address a few of them without consulting an HVAC service technician. 

Supply Registers

During the heating season, supply registers provide heated air into the rooms throughout your home. Your supply registers may be located on the floor or in the ceiling. 

 If one room is colder than the rest of your home, please check to ensure the following are true: 

  • The vent is open on the register 
  • The supply register isn’t blocked or covered  
  • When your furnace is running, air is coming from the vent 
  • If the supply register is uncovered and open but airflow is still weak (or there’s no airflow at all), your supply registers likely aren’t to blame. 

We’ll cover two more common heating problems that could be restricting airflow later in this article. Nevertheless, there is another less common issue that’s worth mentioning here. 

Over time, your air ducts can accumulate dust, dirt, and other debris. And because heated air travels through your ductwork, the buildup of dirt in your ductwork can restrict airflow. 

In any case, the National Air Duct Cleaners Association suggests having ductwork cleaned every three to five years to promote good health and airflow. For more information, check out this article that covers the best practices for ductwork cleaning. 

Dirty Furnace Filter

Furnace filters help remove dirt and other debris from the air in your home throughout the year, which protects both your family’s health and your HVAC system. 

But the more pollution and debris your filter removes from the air, the more it restricts airflow. It only gets worse over time. 

If your air filter starts affecting airflow significantly throughout your system, you may notice three things: 

  • Poor airflow coming from all supply registers  
  • It takes your furnace longer to warm up the home 
  • The temperature is uneven throughout the home 

These are often the first signs that your air filter needs replacement. The longer a dirty filter remains in your system, the dirtier it will get. This will lead to more serious problems, which we’ll discuss later in this article. 

In any case, we can’t over-emphasize how important it is to change your furnace’s air filter regularly. Dirty and clogged filters are the number one cause of airflow problems in the homes we visit. This can be very expensive. How often your filter needs to be replaced depends on the type of air filter you have in your home. The standard one-inch air filters typically need to be replaced every 30 days (if not sooner). Certain types of four-inch air filters can last up to a year without ever being replaced. Your filter’s packaging should include additional information on when you should replace it. 

Having said that, you might need to replace your air filter sooner if: 

  • You use candles frequently  
  • You have indoor pets that shed or molt 
  • You live in an area with a lot of construction or dust 

Although these are the most common factors we have seen here in Central Ohio, there may be additional factors depending on your home. For the best results, monitor your system’s performance. If you notice some of these issues, check your filter. 

For more information, check out this article that breaks down how, why, and when you should change your filter. 

Air Duct Dampers

Next, we’ll look at ductwork dampers. Like supply registers, air duct dampers allow you to adjust how air moves to specific areas of your home. However, each system’s dampers are located near their furnace. 

Dampers are set differently for the heating and air conditioning seasons respectively. These settings can help compensate for seasonal changes. If you notice that part of your home seems chilly, your dampers may not be positioned for home heating season. Although homeowners can reposition their dampers on their own — repositioning dampers can involve a lot of trial and error. If you’ve never done this before or you aren’t comfortable adjusting the dampers yourself, one of our friendly HVAC service technicians at Five Star Home Services can help. Ask your technician to adjust your dampers for winter during your furnace’s annual tune-up. 

Undersized Furnace

Although undersized equipment doesn’t always affect airflow, it can hinder a furnace’s performance. 

When this case, an undersized furnace refers to one that’s not powerful enough to adequately heat your home. If your furnace is too small for your home, it’ll run more often than it should in an attempt to heat your home. Nevertheless, despite frequently running, an undersized furnace won’t be able to adequately heat your home. This is a problem!  

If your furnace is undersized, you may notice the following: 

  • Uneven temperatures throughout your home 
  • Upper floors and rooms farthest from your system remain cold 

Although oversized HVAC equipment tends to be more common, undersized equipment is still too common here in Central Ohio and throughout the country. Eventually, we will also explore oversized furnaces. 

Your Furnace Continues Turning Off & On

When a home heating system continues turning off and on without running a complete heating cycle, we call this short cycling. Short cycling sucks! If your HVAC equipment is short-cycling due to ignition issues, it might try starting three times without running. In newer furnaces, this typically results in a soft lockout. The furnace will go through this process two more times. Then, after the final attempt, a newer furnace will enter a hard lockout, which only an HVAC service technician can address. 

Older furnaces on the other hand, can go into a hard lockout after the first three attempts to ignite. 

This is not good. When your furnace enters a lockout, it won’t generate any heat. But if an issue doesn’t trigger a safety feature, it may produce heat even while short cycling for some time. 

Common issues that cause short cycling: 

  • Dirty burners  
  • Dirty Furnace Filter 
  • Dirty furnace filter 
  • Dirty flame sensor 
  • Oversized furnace 

If your furnace is starting to short cycle, this can be a warning sign of overheating. 

In the previous section, we discussed how dirty furnace filters can affect your furnace’s performance by restricting airflow. With enough airflow restriction, your furnace will overheat. This is another huge problem because overheating can shorten your furnace’s life expectancy. If left unchecked, overheating can damage your furnace’s components; it can damage the heat exchanger, which is a metal part that heats the air circulating throughout your home. Heat exchangers can cost as much as $3,500 to replace. 

Additionally, overheating can also damage a home heating system’s safety feature, including the limit switches. Limit switches shut down your furnace when it overheats. But limit switches can also get stuck if your furnace overheats. 

Dirty Flame Sensor

Flame sensors are safety features that turn off the gas when a furnace’s burner doesn’t light. This ensures that gas doesn’t fill your furnace cabinet, which is extremely important. Because a flame sensor sits in open flames from the burners, it accumulates soot over time. If the flame sensor isn’t cleaned off, eventually it won’t recognize whether the burners are lit or not.  

On the bright side, this is usually a relatively quick fix. One of our HVAC service technicians can clean off a dirty flame sensor promptly. We can also clean your flame sensor during your annual furnace tune-up maintenance visit. This will help ensure that you don’t get stuck without heat on a cold day. 

In any case, as easy as this fix is, we still suggest leaving the flame sensor cleaning to our professionals. Flame sensors need to be positioned at specific angles. Otherwise, the heating system will continue kicking on and off without heating your home. 

A Five Star Home Services, our HVAC service technicians clean the flame sensor during furnace tune-up maintenance calls.   

Dirty Burners

Furnace burners help channel the open flames to provide heat in your home. 

Similar to flame sensors, burners can accumulate soot over time, which can cause clogs. Once the burners fail to light, the flame sensor turn the furnace off. Additionally, like flame sensors, your HVAC service technician can address dirty burners by cleaning them. 

Oversized Furnace

Not all oversized equipment experiences lockouts. However, if your furnace is oversized, it probably won’t run a full heating cycle.  

If this is the case, an oversized furnace refers to a furnace that’s too powerful for your home. 

Normally, when it comes to anything outside of HVAC equipment, we favor bigger and more powerful options. But the size of your HVAC equipment isn’t an option. To get the most out of your system, your HVAC equipment needs to be the right size.  

If your home heating system isn’t the right size for your home, you’ll lose out on more than comfort. This is not good. You might need to replace an improperly sized furnace 10 to 15 years sooner than an accurately sized furnace.   

Your Furnace Isn’t Running

Few things are more serious in a home than a furnace that stops running during wintertime. This is especially the case if your furnace quits during a time when HVAC service technicians are in high demand. Unfortunately, HVAC equipment always seems to break down when you need it the most.  

There is a reason for this. If your furnace is under strain, it’s already working harder to keep your home heated. Nevertheless, during cold snaps, a strained furnace has to work even harder. 

Additionally, other small issues can cause your home heating system to shut down. You may be able to address some of these on your own without our help. 

Common types of heating problems that can prevent your furnace from running include the following: 

  • Tripped breaker  
  • Thermostat settings 
  • Dirty furnace filter 
  • Malfunctioning igniter 
  • Thermostat Settings 

Although thermostat settings aren’t always to blame, checking these areas helps if you have to wait a few days for an HVAC technician; they can help to check some of the factors you can control. 

Thermostat troubleshooting checklist: 

  • Make sure the thermostat is switched to “heat.”  
  • If you have a thermostat with batteries, try replacing the batteries. 
  • If you have a Wi-Fi thermostat, make sure it’s connected to the Internet. If the thermostat doesn’t connect, you may need to restart your router. 

Dirty Furnace Filter

In previous sections, we discussed minor symptoms and warning signs that your furnace filter needs to be changed. If you leave it unchecked for long enough, a dirty furnace filter can leave you without heat entirely. 

In the previous section, we mentioned how dirty furnace filters can cause your furnace to overheat and short cycle. Over a long enough period, this can trigger a hard lockout if your furnace doesn’t have proper airflow. Only a professional HVAC service technician can unlock your furnace after a hard lockout.  

If your home heating system quits running because of a dirty air filter, your service technician should also check the condition of your furnace’s components. 

At Five Star Home Services, HVAC service technician inspects a furnace’s heat exchanger during a furnace tune-up. 

Tripped Breaker

Sometimes furnaces can trip the circuit breaker. No worries when this happens! You can reset the breaker, and the chances are that it will happen again. If it continues to happen, however, one of our service technicians will likely need to take a look at your system. 

One of the reasons your home heating systems may trip a breaker is because of a strained blower motor — a component that’s responsible for circulating air throughout the home. 

Blower motor can get strained because of several factors, including the following:  

Diminished airflow throughout the system. Dirty furnace filters and closed or blocked registers can subject your blower motor to strain. You can address these by regularly changing your furnace filter and checking your registers (which we discussed earlier in this article). 

Buildup of debris on the blower fan. Like your furnace filter, your blower fan can accumulate dirt, pet hair and other debris over time. Your HVAC service technician can address this by deep-cleaning your blower fan. 

Malfunctioning Igniter. Your furnace’s igniter provides the spark that heats your home. But your igniter can wear out over time. Most igniters can last between 10 to 20 years, depending on the type of igniter and how it was installed. Fortunately, our HVAC technicians at FIve Star Home Services are able to replace your igniter quickly. 

How Improper Installation Affects Your Comfort

Improper installation sets your HVAC equipment up for failure from the start. 

Your HVAC provider should install your heating system according to manufacturer specifications and local building codes. This helps set up your furnace to operate safely and efficiently. 

Choosing an HVAC contractor that follows industry best practices is the best way to ensure that your HVAC equipment is properly installed. 

According to these best practices, a load calculation needs to be performed and pull permits are required before installing the new system. 

On the one hand, permits are required by law. In addition to covering, you legally, permits also help ensure your safety. Once your HVAC contractor installs your equipment, a third-party inspector will inspect the final installation to ensure it complies with local building codes and manufacturer specifications. 

For everything else you’d like to know about your furnace – from installation and daily function to routine preventative maintenance – give us a call or check out our guide to home furnaces. 

Three Steps That Help Prevent Common Heating Problems

Unfortunately, no one can completely avoid furnace repairs or heating problems. Eventually, everyone has to call a pro. Nevertheless, we all can prevent problems for as long as possible. 

The following 3 steps help prevent common heating problems: 

  • Change your air filter regularly 
  • Schedule a furnace tune-up every year 
  • Choose an HVAC contractor that follows industry best practices 

These steps can help you get the most out of your HVAC equipment, especially when used together. 

If you’re looking for an HVAC company to help protect your system, we’d love to speak with you! 

At Five Star Home Services, we’re dedicated to your comfort and your HVAC system. We have skilled service technicians and knowledgeable comfort specialists on staff to help you customize your HVAC system. We always take the time to understand your needs and explain all possible solutions in as much detail as possible!   

To schedule a service appointment for your furnace, give us a call today at (833) 405-8009.

Table Of Content