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Gas Furnace Buying Guide for Homeowners

By December 20, 2019August 26th, 2020No Comments

Gas Furnace

When your furnace experiences problems or just stops working altogether, you are faced with a troublesome decision: Do you try to repair the broken part, or invest in a completely new system? The first thing to consider when faced with this question is the age of your current gas furnace. If it is older than 10 years, chances are there have been advancements in efficiency or industry standards that you can benefit from if you replace your system.

Next, consult your warranty information. Many furnace manufacturers cover the heat exchange for 10 or more years, while some have lifetime coverage. Depending on the parts that need to be replaced, your furnace might be covered by a manufacturer’s warranty. Additionally, many HVAC installers offer guarantees on their work, which can save you money if they are responsible for the problem.

Often, HVAC professionals recommend that you update or replace your existing gas furnace when you replace your central air unit. This is an excellent way to save money over time, as a high-efficiency furnace and a cooling system that are the same age and brand work together better than a mismatched-efficiency set of an older furnace and new AC unit. Unfortunately, this is not always a feasible option financially, as high-quality HVAC units can be priced in the thousands. If your current furnace’s age is within five years of the new AC unit, it should work well with your new cooling unit.

Ultimately, it’s up to you if you want to replace your furnace. To help you decide, consider the current efficiency of your home furnace, its age, and if you are willing to replace a part that may continue to fail in the years to come. (continue below)

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Furnace Buying Guide

Gas Furnace Efficiency: It’s Not Just the Money Size Matters

Unlike most major appliances that get better in functionality as they increase in price and size, furnaces need to be the right size for the layout of your home. This means that buying the biggest and most energy-efficient furnace on the market is typically not the best answer for your home.

Every home is different, whether in its layout, ventilation system or materials. A natural gas furnace that is too small will not be able to produce adequate heat in the winter or push enough cool air in the summer. Conversely, a system that is too large for your home will cost more to run and not efficiently maintain correct temperatures.

Energy Efficiency

If your gas furnace was installed in your home more than 15 years ago, you are pretty much guaranteed to be heating your home inefficiently. With a high-efficiency furnace, the amount of gas you need to warm your home decreases, as do the charges on your utility statements.

When selecting the best furnace, consider the device’s annual fuel utilization efficiency (AFUE) rating. This number is represented as a percentage and indicates how much heat a furnace can obtain from each cubic foot of gas. To clarify even more, for example, an AFUE rating of 96 percent means that up to 96 cents of every dollar is used to warm your home. The national standard for lowest allowable efficiency is 78 percent, and many modern units achieve upward of 98 percent.

A furnace with a high AFUE rating can save you a significant amount of money in heating and electricity bills. While a unit with more than 90 percent AFUE generally costs more than one with an 80 percent rating, you’re likely to recoup any difference of cost over the furnace’s lifespan.

Another way to increase the efficiency of your new furnace is to have a compatible programmable thermostat installed along with it. Many gas furnace manufacturers have their own lines of thermostats that can push and run your furnace to its peak efficiency levels. While this is an additional cost, an updated, compatible thermostat allows you greater control over your home’s temperature and comfort levels.

What You Need to Know About Furnace Installation

A furnace is a major home-improvement investment, so any knowledge you can arm yourself with before deciding which new unit to purchase can save you time and money in the long run. Below are some key elements to forced air heating that you need to be aware of as you talk with your local HVAC professional.

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Types of Gas Furnaces

Gas furnaces come in two varieties, single-stage and two-stage. Single-stage furnace blowers use a single-speed blower, which switches on and off until it reaches the desired temperature. These furnaces are usually older models, but you can still purchase one for your home that has an AFUE of 80 percent.

While these units can be a less expensive investment initially, the lower efficiency from switching on and off constantly ends up costing you more over time than a furnace with a variable-speed blower. That being said, if you have a smaller home, consult with your HVAC professional to see if a single-stage furnace would be a more viable option.

Two-stage gas furnaces operate similarly to single-stage ones, but when the temperature drops and the first stage is not producing enough heat, the second stage turns on to supplement your home’s heating needs. This second stage allows your furnace to produce and use more heat with less effort and fuel. Another great side effect of a two-stage unit is that it generally runs much quieter than the single-stage models.

Variable-Speed Fans & Modulating Valves

Variable-speed fans are an additional option to increase the efficiency of the furnace. Rather than constantly turning off and on and blowing at an unalterable speed, the variable-speed blower has the ability to slow down the motor to provide constant heat with a longer, less stressful cycle. This speed control allows the furnace to use less gas and to operate much more quietly, a great bonus for heating large homes or awkward floor plans. Generally, two-stage furnaces are equipped with variable-speed fans, helping them run even more efficiently than they would with a standard, single-speed blower.

Some furnaces are equipped with a special modulating gas valve. This specialty component works in tandem with a variable-speed blower to provide consistent temperatures. This is much like driving an automobile on a freeway at a constant pace, rather than stopping and starting at every stoplight downtown. Modulating furnaces can reach an AFUE of up to 98 percent. While they cost more to purchase, these furnaces maximize your comfort levels and can greatly reduce your overall energy costs.

What Else Is Important When Selecting a Gas Furnace?

Gas furnaces have other factors to consider beyond efficiency and installation. For example, furnace warranties vary between manufacturers. Yearly maintenance and reliability are also important to consider.

Warranty & Rebates

One of the most important elements of even the most high-efficiency furnace is its warranty. Replacing a furnace in its entirety is an incredibly expensive endeavor, and having to replace it every few years is problematic from a financial-planning standpoint. The ideal furnace carries two individual warranties: one for the heat exchange and another for all other parts. In addition, the best contractors provide a labor warranty to back up their work.

The heat exchange is the heart and soul of the furnace, as it influences how much heat a unit can get from burned gas. This warranty can extend up to and beyond 20 years, whereas the warranty for all parts may only be five to 10 years. Also, the brand of the furnace can influence its reliability. Lesser-known brands generally do not have quality parts or long warranties, and while they may be cheaper initially, repairs will cost you more in the long run.

Be sure to discuss the availability of manufacturer rebates or tax credits with your installer. This can be a great way to save money and offset the initial cost of a new furnace. Federal and local governments are encouraging homeowners to improve their dwellings’ energy consumption, and you may be able to deduct the purchase of a new heating system on your taxes. Check with your contractor and tax agent to confirm any eligibility or programs currently available.


The lifespan of your furnace is influenced greatly by how well you, the owner, perform regular maintenance. This doesn’t mean you have to know how to repair and rebuild a furnace unit, just that you should be able to perform basic maintenance tasks such as changing and correctly installing air filters, keeping the airflow path free of obstructions, and giving the main unit a visual inspection a couple times a year.

Air filters are one of the most important components of an efficient gas furnace. While older designs and cheaper furnace filters block large particles, they do not remove small particles such as pollen from the air that circulates through the system.

Fortunately, there are high-efficiency filters that you’re better off using, especially if you have allergies, live in a dusty region or have pets that shed. While the high-efficiency filters cost more, the amount of particles they remove from the air helps you and your furnace breathe easier.

High-efficiency filters need to be changed approximately every three months, but you may need to replace them more often if you have multiple pets or someone who smokes in your home. While three months may seem quite often, if you use cheap, thin filters, you need to replace them at least every month, as they do not take as long to reach capacity.

Keep the area around your furnace free from obstructions, such as boxes, that can block air circulation. The burner inside your gas furnace needs to have enough oxygen to function properly, and a reduced air intake can be dangerous and cost you more money. Also, a couple times during the year, take a quick visual assessment to see if anything looks wrong, such as loose wires, bent panels or any ventilation pipes that need repair. Simple maintenance chores such as these can help keep your furnace in tip-top shape for years and your family toasty during the winter months.

Being left in the cold is definitely no fun, but fortunately, you won’t be in the dark when you use our articles on gas furnaces to assist your educated decision. While you consider the different brands of furnaces as you read through this site, remember that it is just as important to find a local HVAC professional who will give you the best service possible by putting your needs before a sale. The best combination for your home and wallet is to choose the most efficient gas furnace that provides adequate coverage and to have it installed correctly by a qualified professional.

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