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Furnace Replacement: How to Choose & Install a New Furnace

Updated on March 4, 2025

Your home’s furnace plays a critical role in keeping your living space warm and cozy during the colder months. However, like all appliances, furnaces don’t last forever. When the time comes for furnace replacement, it’s crucial to understand which options suit your home best and how to ensure a smooth installation process. 

If you’re considering replacing your furnace, this guide will walk you through everything you need to know, including:

  • Signs it’s time for a furnace replacement 
  • Understanding the installation process (in 5 steps) 
  • How to choose the right furnace for your needs 

🤔 Is It Time for a Furnace Replacement? 

A home high efficiency furnace with a residential gas water heater & humidifier.
A home high efficiency furnace with a residential gas water heater & humidifier.

Your furnace plays a critical role in keeping your home warm and comfortable, especially during colder months. However, like any appliance, it doesn’t last forever. Ignoring the signs of a failing furnace can lead to higher energy costs, more frequent breakdowns, and even unsafe conditions in your home. Before jumping into the process of choosing and installing a new furnace, it’s important to know when it might be time to replace your existing system. Here are a few key signs to watch for: 

  • Age of Your Furnace: Most furnaces last 15-20 years. If yours is older, it may be losing efficiency and reliability. 
  • Rising Energy Bills: Higher heating costs often mean your furnace is working too hard to maintain the temperature. 
  • Frequent Repairs: Multiple repairs each year? It might be more cost-effective to replace your furnace. 
  • Uneven Heating: Cold spots or uneven warmth in your home could indicate your furnace isn’t distributing heat properly. 
  • Strange Noises or Smells: Banging, rattling, or persistent odors could signal serious mechanical issues.

✅ 5 Steps to Install a New Furnace 

air conditioning technician
air conditioning technician

Replacing a furnace might feel overwhelming, but with a clear idea of the installation process and the right help, it’s manageable. Here’s a step-by-step breakdown of what to expect:

1. Assess and Remove the Old System 

The first step in furnace installation is a thorough inspection of your existing system. Technicians will carefully evaluate the condition of your current furnace and ductwork, identifying any issues or inefficiencies that need addressing. Once the assessment is complete, they will safely disconnect the old furnace, ensuring no surrounding areas are damaged and that safety protocols are followed. Proper disposal of the old system is crucial, as it ensures compliance with environmental regulations and eliminates potential hazards. This step sets the stage for a smooth installation process.

2. Ensure Proper Ductwork 

Your furnace relies on your ductwork to distribute warm air throughout your home efficiently. During this step, technicians will closely inspect your existing duct system to check for leaks, cracks, or other damage that could compromise performance. Any issues found will be addressed, such as sealing leaks or replacing damaged sections. Additionally, technicians may recommend improvements to optimize airflow or accommodate the new furnace. Ensuring the ductwork is in top condition is critical for maintaining energy efficiency and maximizing the performance of your new heating system.

3. Prepare the Space 

Before the new furnace is installed, the designated installation area must be properly prepared. This includes cleaning the space to ensure debris or dust doesn’t interfere with the setup process. Technicians will also check that the floors are stable and level to support the furnace securely. Proper clearance for ventilation and access will be ensured for both safety and ease of future maintenance. Preparing the space thoroughly not only facilitates a smooth installation but also ensures the furnace operates safely and efficiently in its new environment.

4. Install the New Furnace 

With the old system removed and the space prepared, the new furnace can be carefully installed. This involves securing the unit in place and connecting it to the power or gas supply. The furnace is then hooked up to your ductwork, ensuring airtight connections to prevent heat loss. Technicians will verify that all connections, including electrical wiring and gas lines, are properly secured and meet local safety codes. This detailed process ensures your new furnace is installed correctly, minimizing the risk of future issues and maximizing energy efficiency.

5. Test and Fine-Tune 

Once the installation is complete, the new system is thoroughly tested to ensure it functions as intended. Technicians will power on the furnace and monitor its performance, checking for consistent airflow, proper temperature regulation, and efficient operation. They will calibrate the system to ensure optimal heating throughout your home. Additionally, they will guide you through operating the thermostat and provide essential maintenance tips to keep your furnace running smoothly. This final step ensures your new furnace is ready to deliver reliable, efficient heating for years to come.

👉 Choosing the Right Furnace for Your Home 

Central Gas Heater Repair
Central Natural Gas Heater Repairing by Professional Caucasian Heating Technician.

Selecting the perfect furnace for your household requires thoughtful consideration. Here are the main factors to evaluate when making a decision:

Furnace Type 

When choosing a furnace, there are three main options to consider, each with its own set of benefits and drawbacks. Gas furnaces are a popular choice for most homeowners due to their efficiency and powerful heating capabilities. They work quickly to heat a home and are often cost-effective in areas where natural gas is readily available. Electric furnaces, on the other hand, are a budget-friendly option that requires minimal maintenance. However, they tend to result in higher energy costs in colder climates where heating demand is greater, as electricity can be more expensive compared to natural gas. Oil furnaces are another alternative, typically used in areas without easy access to natural gas. While they can be effective in heating homes, they are generally less energy-efficient than gas furnaces and can require regular maintenance, such as ensuring the oil supply is replenished. By understanding your specific heating needs, the availability of utilities in your area, and your budget, you can determine which type of furnace best suits your requirements.

Energy Efficiency 

Energy efficiency is a critical factor to consider when selecting a furnace, as it directly impacts your energy bills and environmental footprint. Look for furnaces with a high Annual Fuel Utilization Efficiency (AFUE) rating, which measures how effectively a furnace converts fuel into heat. Systems with higher AFUE ratings are significantly more efficient, meaning they waste less energy in the heating process. Modern furnaces can achieve AFUE ratings of 90% or higher, offering far superior efficiency compared to older models. Investing in a high-efficiency furnace can lead to noticeable savings on your utility bills over time, making it a smart long-term investment for both your comfort and finances.

Sizing Your Furnace 

Properly sizing your furnace is essential to ensure your home is heated effectively and efficiently. A furnace that is too small for your home won’t be able to keep up with heating demands, leaving your space cold and uncomfortable during the winter months. On the other hand, an oversized furnace will cycle on and off too frequently, leading to wasted energy, higher utility bills, and premature wear and tear on its components. To determine the right furnace size, it’s important to work with a professional who can calculate your heating needs based on factors such as the square footage of your home, the quality of its insulation, and the local climate. A correctly sized furnace will not only keep your home comfortable but also help you save on operating costs and extend the lifespan of your heating system.

Additional Features 

Modern furnaces offer a variety of additional features designed to enhance comfort, convenience, and energy efficiency. Variable-speed blowers, for example, allow the furnace to adjust its airflow to maintain a consistent temperature throughout your home, improving comfort and reducing energy consumption. Smart thermostats provide advanced control over your heating system, enabling you to program temperature settings, monitor energy usage, and adjust heating remotely via smartphone apps. Zoned heating systems can further improve comfort by allowing you to set different temperatures for specific areas of your home, ensuring energy is only used where it’s needed. While these features can make your heating system more efficient and user-friendly, they often come with a higher upfront cost. Consider your budget and specific needs to decide which additional features are worth the investment for your home.

🏡 Furnace Replacement Guide

When it comes to furnace replacement, Comfort Systems of Montana is the team you can trust to keep your home warm and cozy through even the harshest Montana winters. With years of experience, certified technicians, and a commitment to personalized service, we make the process seamless and stress-free.

Whether you need expert guidance on choosing the right furnace or professional installation you can count on, we’re here to ensure your home stays comfortable for years to come. Contact Comfort Systems of Montana today to schedule your free consultation or request a furnace replacement quote. Let us help you find the perfect heating solution for your home!



Related FAQs


What is the life expectancy of my unit?

HVAC systems last an average of 10 years. However, for your equipment, it may differ. Variables that affect life expectancy include the type of system, climate and the regularity of routine maintenance.

What size HVAC equipment is right for my home?

Many factors affect the sizing and specifications of your system, including square footage, insulation, window surface and configuration, geographic location of your home, and duct sizing and arrangement. A technician from Comfort Systems of Montana can perform an in-home load analysis to determine which equipment combinations will perfectly suit your home and your family’s needs. Depending on the construction of your home, one (1) ton of air conditioning can cool anywhere from 300 to 800 square feet. You can ensure that the system you purchase is the right size and not smaller or larger than you require, by having your heating and cooling needs evaluated by a licensed professional.


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About The Author

Comfort Systems of Montana

Air conditioning contractor in Four Corners, Montana