One of the first things you might think about when you decide to replace your furnace or buy a new one is, “How long will this take?” The good news is that most of the time, you can install a furnace in one day. The process usually takes between 4 and 8 hours, but the exact time depends on your home, the state of your current system, and how complicated the work is.
It’s also important for homeowners to know how furnace installation is different from a full HVAC installation, since adding an air conditioning unit or redoing ductwork can make the job take longer. We’ll go over the steps involved in the installation process, what can change the timeline, and what you can realistically expect when you upgrade your heating system.
How Long Does It Take to Put in a New Furnace?
You should plan on spending about half a day installing a new furnace, whether it’s a replacement or the first time you’ve done it. It might only take four to six hours to replace something if the new one is the same size and type as the old one.
But the process isn’t always that easy. The installation will probably take longer if your contractor needs to change the ductwork, the gas lines, or the electrical system. Older homes or homes with high-efficiency furnaces that need special venting can also take longer to work on.
So, even though many homeowners are pleasantly surprised at how quickly the job gets done, it’s best to plan for a full day just in case your project needs more work. If your system keeps shutting down during operation, you may also want to check out why your furnace keeps turning off before assuming it’s an installation issue.
How long does it take to install HVAC compared to just a furnace?
If you’re replacing your whole HVAC system, not just the furnace, the installation will take longer. Furnace-only jobs usually take one day to finish. However, a full HVAC installation can take 6 to 10 hours and sometimes even longer if major changes are needed.
Usually, adding central air conditioning or replacing ductwork takes longer. Refrigerant lines, electrical connections, and outdoor condenser setup are all things that AC units need and can’t be rushed. If your installer is putting in both heating and cooling at the same time, you’re basically getting two systems that work together in your home.
Because of this, contractors often plan full HVAC installations over several days, especially in bigger homes or when new ductwork needs to be run.
Things that affect how long it takes to install
Every home is different, so every furnace installation is different. A few key things can have a big impact on the timeline:
- Type of installation: A simple replacement is faster than a first-time install, which may need new ductwork or gas line connections.
- Condition of existing infrastructure: Older homes often need to have their ductwork, electrical wiring, or vents updated to meet current code.
- Type of furnace: High-efficiency furnaces need special venting and drainage, which can take an extra couple of hours. If your unit struggles with ignition, check our guide on furnace ignitor replacement costs.
- Additional upgrades: Installing a smart thermostat, zoning system, or whole-home humidifier with the furnace can make the job take longer.
Because of these factors, most HVAC professionals won’t give you a specific time frame until they’ve been to your home.
The Process of Installing a Furnace Step by Step
Knowing what happens on the day of installation can help you set your expectations. Most contractors follow a similar process, but each one does things a little differently:
- Pre-installation prep: Before the installation, the technician looks around your home, takes final measurements, and covers your floors.
- Taking out the old furnace: If you’re replacing an old one, it usually takes one to two hours to disconnect it and take it out.
- System preparation: Before the new furnace goes in, any changes to the ductwork, wiring, or gas lines are made.
- Installing the new furnace: The unit is put in place, connected, and secured.
- Testing and calibration: The contractor runs the system, checks the airflow, makes sure it is safe, and calibrates the thermostat. If you notice your thermostat not turning on heat even after installation, it could be a simple wiring or calibration fix.
- Cleanup and walkthrough: You’ll learn how to use your new system and what to look out for.
This sequence explains why the job usually takes 4 to 8 hours, even though each step takes a different amount of time. During testing, if you notice your heat blowing cold air, that’s often a separate issue unrelated to installation and may require troubleshooting.
How long each stage usually takes
To put numbers to the steps:
- Taking out the old furnace takes about one to two hours.
- Putting in the new furnace and hooking it up will take 2 to 3 hours.
- Changes to the ductwork or lines, if necessary, will take 1 to 3 hours.
- Testing, calibrating, and going through the steps: 1–2 hours.
That comes to about one workday for installs that only include the furnace. It can take 6 to 10 hours to replace an entire HVAC system, and it can take up to two full days if major ductwork changes are needed.
Why it’s important to take the right amount of time to install
Never try to hurry up the installation of a furnace. If a system is put in too quickly without the right checks, it can cause problems like:
- Short cycling means that the system turns on and off a lot.
- Poor air flow and heating that isn’t even.
- Less efficiency and higher costs for energy.
- More wear and tear that makes the furnace last less long.
If you take the right amount of time, you can make sure that your furnace is the right size, is safely connected, and is set up to work well and keep you comfortable.
What Will Happen After Installation
After the installation is done, your contractor will test the system to make sure it heats up properly. They will also show you how to use your new thermostat and tell you when to schedule maintenance. It’s normal to notice small changes in the first few days as the system gets used to itself. For example, new parts may smell a little different when they heat up. Also, don’t forget ongoing care—something as simple as changing your furnace filter regularly helps your system run more efficiently and last longer.
Call your installer right away if you hear strange noises, feel weak airflow, or see your furnace turning off too often. From the first day, a properly installed furnace should run quietly, evenly, and without fail.
FAQs for Furnace Installation
How long does it take to put in a new furnace?
Installing a new furnace typically takes between 4 and 8 hours. If the job is straightforward, such as replacing an existing unit with a similar model, it may be completed in half a day. However, more complex projects—like updating ductwork, gas lines, or electrical connections—can extend the installation to a full day.
On average, how long does it take to install a furnace?
On average, furnace installation takes about half a day, or 4 to 6 hours, when replacing an old unit with a new one of similar size and type. If additional modifications are needed, such as upgrading ductwork or venting, the process can take closer to 8 hours.
How long does it take to install HVAC compared to just a furnace?
Installing only a furnace usually takes one day or less, but a full HVAC installation that includes both heating and cooling systems can take 6 to 10 hours and sometimes up to two full days. The longer timeline is due to the extra work required for air conditioning components, refrigerant lines, and outdoor unit setup.
Is it possible to put in a furnace in one day?
Yes. In most cases, furnace installation can be completed in a single day. Unless major modifications are needed, homeowners can expect their new furnace to be installed and running by the end of the same day.
Do I have to be home while the installation is going on?
It’s strongly recommended that you stay home during furnace installation. Being present allows you to answer questions, approve any unexpected decisions, and receive a walkthrough from the technician once the job is complete.
How long will a new furnace work after it is put in?
A properly installed and well-maintained furnace should last 15 to 20 years. Regular tune-ups, timely filter replacements, and professional maintenance will help extend its lifespan and keep it running efficiently.
Last Thoughts
The amount of work that needs to be done will determine how long it takes to install a furnace, but most homeowners should expect the job to take 4 to 8 hours. If you want to install both heating and cooling systems, it will take longer—usually a full day or two.
You’ll be better able to plan your project if you know what factors affect how long it will take to install. The most important thing to do is to hire a qualified HVAC professional who won’t rush the job and will make sure the system is safe, works well, and will keep your home comfortable for years to come.
