Larry Cook Heating & Cooling

Should You Replace AC and Furnace at the Same Time? 

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Replacing air conditioner? Replacing Furnace? Or both? Many customers wonder whether they should replace their air conditioner and furnace at the same time, or if they are better off only replacing one system at a time, as needed.

The best way to ensure that your air conditioner and furnace are performing at their top rated efficiency levels is by replacing your furnace at the same time as you replace your air conditioner. While it can be costly to replace your entire HVAC system, when your entire HVAC system is running efficiently it can actually save you money over time.

Most of the time, customers are experiencing issues with their air conditioner before they see issues arise with their furnaces. This is because the average lifespan of a furnace is longer than the lifespan of an air conditioner. In this article, we’ll cover factors to consider when deciding whether or not you should replace your AC and furnace at the same time. Keep reading to learn more.

HVAC System

The majority of homes in Kansas have heating and cooling equipment that work as a team. For example, most homeowners have inside their home an air handler or blower, evaporator coil, and ductwork, and outside of their home, an air conditioning unit. According to ENERGY STAR®, “the only way to ensure that your new air conditioner performs at its rated efficiency is to replace your heating system at the same time. It’s especially recommended if your furnace is over 15 years old. If you purchase a new energy-efficient air conditioner but connect it to an older furnace and blower motor, your system will not perform to its rated efficiency.”[1] ENERGY STAR® recommends that air conditioners and furnaces be replaced together to meet installation guidelines.

Due to the fact that the majority of HVAC systems work together as a team, consider that a new air conditioner (or furnace) may not operate well with the old furnace (or air conditioner). When air conditioners and furnaces are not running compatibly, it’s just a matter of time before one of the systems has a problem. It’s worth the time and money to invest in an air conditioner and furnace that will work together without compromising efficiency.

Replacing Air Conditioner and Furnace Timing

Wondering when to replace AC unit or furnace, or both? When it comes to the timing of replacing an air conditioner and furnace, knowledge is key.

Below we discuss a few other factors to consider while thinking about when and whether to replace your air conditioner and furnace at the same time.


We understand that replacing an HVAC system is a large investment. However, it’s important to understand that when an HVAC system is running efficiently, you should be saving money on your utility bills. Additionally, be sure to consider the warranties that you receive when replacing your air conditioner and furnace simultaneously. Warranties provide peace of mind that if your system requires repair, you will be saving money on the necessary repairs.


Replacing your air conditioner and furnace at the same time could make a significant improvement to your year-around comfort.

Age of Furnace 

If your furnace is nearing the 15-year mark then you should be thinking about investing in a new system sooner rather than later. If you already need a new air conditioner, then replacing the two systems together is generally recommended. Selecting a new furnace that is compatible with your new air conditioner will help with the overall efficiency of your HVAC system and help cut down on repair costs that you would otherwise need in the future.



When customers opt to replace their air conditioner and furnace at the same time, they can rest assured that their HVAC system as a whole is being installed correctly and according to the manufacturer’s guidelines.

Maintenance and Repair

The likelihood of needing costly repairs is greatly reduced when customers decide to replace their air conditioner and furnace at the same time. We’ve noticed that customers that invest in a regular HVAC maintenance plan spend less money on repairs, as well.  

Factors to Consider When Replacing Both Your AC and Furnace

Factors to consider when replacing both your air conditioner and furnace, in addition to cost, is your overall HVAC system’s age, the SEER rating of your HVAC system, and HVAC maintenance packages.

System Age 

How long ago did you install your air conditioner and furnace? If the air conditioner and furnace were installed at the same time, and you learned that your air conditioner or furnace is nearing the end of its lifespan, then there is a good chance that the lifespan of the other system will soon follow.

SEER Rating

Our blog post on Understanding Seasonal Energy Efficiency Ratings (SEER) will help you understand the importance of efficiency and how it can impact your finances. [LINK TO SEER RATING POST]. To ensure that your air conditioner is performing at its proper SEER, it’s best to replace your furnace at the same time. Why? HVAC systems work together. For example, an air conditioner will use a furnace’s fan to blow cool air into a home. The furnace blower must be able to keep up with the air conditioner’s staging (i.e., cooling output). If the furnace blower can’t keep up, then the air conditioner will struggle to push cool air throughout your home and won’t be performing to its fullest abilities.

Maintenance Packages

If you make the decision to install a new air conditioner or furnace, or both, you should know that HVAC maintenance is important in all of these circumstances. Dust, dirt, debris, and other contaminants will show up even if you have the best HVAC system on the market. When dust, dirt, debris, and other contaminants inevitably make their appearance, they can build up on your HVAC system causing damage and reducing your HVAC system’s efficiency. Because of this, we recommend that anyone with an HVAC system also schedule regular maintenance for his or her HVAC system. Maintenance appointments are a cost effective way to protect your investment. At Larry Cook Heating & Cooling, we offer maintenance packages to help keep air conditioners and furnaces in tip-top shape, thereby extending the lifespan of our customers’ HVAC systems overall.   

When You Shouldn’t Replace AC and Furnace

You may not need to replace your AC and furnace at the same time when your furnace is less than 10 years told, or if you are sure that your existing furnace is compatible with the new air conditioner that you are installing. The lifespan of furnaces is often longer than air conditioners.  So long as your furnace is working properly and meeting your needs, then you don’t necessarily need to replace your air conditioner and furnace at the same time.  

If you’re still unsure about whether you should replace your air conditioner and furnace at the same time, we encourage you to schedule an in-home consultation with a trustworthy HVAC company. Larry Cook Heating & Cooling offers free in-home consultations. This is a great way to have a conversation with an experienced HVAC professional who can give you their best recommendation based on your particular home and needs. We also offer financing options to help work within your budget, whatever that may be. Contact us today at 316-322-5668 to schedule your free in-home estimate.


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