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Heating

5 Biggest Mistakes Homeowners Make When Buying a Furnace

 November 16, 2021

By  Robert Bradford

It is easy to become overwhelmed when contemplating an expensive purchase for your home, like buying a furnace. Especially when that purchase has an enormous effect on the comfort, health, and safety of your family. While you don’t want to get bogged down trying to make the “perfect” choice, there are a few things you can do to avoid buyer's remorse for the next 10 - 20 years!

The five major mistakes you should avoid when choosing a new furnace for your home are 1) Not hiring a professional to do your installation; 2) Not spending enough time researching contractors; 3) Focusing too much on the brand instead of a quality contractor; 4) Choosing the size by yourself instead of asking the help of an expert, and 5) Selecting an overcomplicated furnace.

Currently, a furnace replacement cost  can be between $2,800 to $7,000 including installation. This range is for the mid to high efficiency gas furnaces. But gas furnace prices are changing rapidly (up of course) so don't be surprised if your estimates are higher.

It is no secret then that buying a furnace is kind of a massive deal because of its costly upfront price and labor. But since it is a necessity to have a healthy and comfortable home, you want to take the time and effort to get the best you can reasonably afford.

This article will help you to make a wise purchase and protect your hard-earned money by shopping for a quality furnace and having it installed the right way.

Mistake #1: Not Hiring a Professional

This will be the most in-depth section of this article because it is, by far, the most important aspect to consider when investing in a new furnace!

The cost of buying a furnace from a knowledgeable contractor is quite high and rising all the time. You may be tempted to base your decision on price alone. So, you jump on the cheapest bargain you can find, or accept the kind offer to have one installed by a friend who knows how to tinker with machines, for a discounted price. You may even have bravely thought you could do the installation yourself!

STOP! No really, please reconsider these options. We understand being on a budget (having a small HVAC company and blog is not as glamorous as it sounds) and often this purchase is a bit of a surprise to your budget. However, the idea of saving a few bucks now when buying a furnace may well cost you hundreds or even thousands in repairs and early replacement costs in the future.

  • More Repairs, Shorter Lifespan: Poor installation is the number one cause of most furnace damage and longevity problems. Worse, it is the major source of safety hazards. The ACHR News cited improper venting, erroneous sizing, haphazard ductwork, and poor wiring as some of the common issues caused by amateur installations.

    The above mentioned source further states that while homeowners may save about 25% by hiring a nonprofessional to install a furnace, there is on average a future payback of twice the savings amount or more to correct errors. The old adage holds true here: it is cheaper to do it right the first time.

  • No Warranty, No Protection: Did you know that the manufacturer of your furnace can void your warranty if they find out you used a nonprofessional to install your furnace? Yes, they can do that.

    A warranty, whether limited or extended, is a written guarantee by the manufacturer that the furnace you bought will function the way it is designed or intended. It provides some reassurance that if your unit breaks within the period covered, the manufacturer will either repair or replace it at little or no cost to you.

    In the warranty, are the terms and conditions that you as a user must comply with to make sure that damage is not caused by negligence or misuse. One of the most common reasons why claims are rejected is due to not hiring a certified and licensed contractor to install and/or repair your equipment. No kidding.

    This is not a clever way for the manufacturer to get out of paying for your repairs. They know that choosing the correct equipment and installing it properly requires tools and training that the average person doesn’t possess.  If you use substandard materials or try to DIY buying a furnace, you could be denying your right to a claim and face expensive repairs out of pocket.

Mistake #2: Waiting Until the Last Minute

One major mistake homeowners make is buying a furnace only when the existing one is already showing signs of serious damages. Some even wait until their old furnace is already broken and inoperable before searching for a replacement!

DON’T. If you wait until the last minute—when you urgently need a working furnace—you increase the likelihood that you will make a decision you’ll later regret.  You could be so desperate to have an immediate replacement, you will not have time to think through your options.

Careful planning and research are essential when buying a furnace, and more importantly, a contractor to install the furnace. This should save you from being forced into buying a furnace that is too expensive yet does not fit your needs at all. It can also prevent you from being swayed by marketing tactics by scheming manufacturers and cunning contractors.

Of course, not every furnace manufacturer and an HVAC contractor is out to get you (not all, but there are a handful!) But you have a good chance of being easy prey to crafty salespersons if they detect your urgency to buy a furnace. Some will even jack up the price knowing you need a new furnace right away.

How do you plan for buying a furnace? Don’t wait for it. Anticipate it.

buying a furnace

The average lifespan of a furnace is 12 to 20 years. Some furnaces are said to last until 35 years, but those are exceptions, not the rule.

As your furnace nears the end of its life expectancy, spend ample time researching your options. Make inquiries to the trusted contractors in your area. While you should spend some time researching specific furnaces and features available, the majority of your research time should be focused on the contractor.

Don’t worry. You don’t have to commit to the first contractor you approached. Take your time to understand what your home needs and your working budget and listen carefully to what the contractor has to say.

If the contractor is pushing you to make rash decisions with the bait of a discount or a marketing hype, take a step back and evaluate. A legit professional does not have to dazzle you with sales talk but gives you sufficient information about your choices. You have to spend the money on a professional installation so make sure it’s a quality job! This doesn’t mean it has to be the most expensive contractor or that it cannot be the cheapest. We’ll get into that more.

Mistake #3: Focusing on the Brand When Buying a Furnace

We said it before, and we are saying again: There is NO SUCH THING as the best furnace brand. Focusing too much on finding the best brand is a waste of precious time. How so?

The truth of the matter is a single manufacturer can produce different brands with almost identical parts. This is called the multi-branding strategy, where a company produces and designs various brands of the same product to cover a wide range of target markets.

Even the self-proclaimed unbiased hub of product information, Consumer Reports, is careful to pronounce the “best” furnace in its comparison of furnace brands. It discreetly shows you some brands’ claims on efficiency, noise level, and prices.

The reliability of a furnace, whether it will last long for many years with lesser repair needs, is greatly dependent on the quality of your contractor rather than the brand. A high quality furnace installed poorly will perform poorly and have a short lifespan. On the other hand, a decent and simple furnace expertly installed can keep you comfortable for a long time with minimal repairs. 

The Department of Energy stresses the key elements of an excellent furnace are efficiency rating, appropriate sizing by a skilled contractor, and regular maintenance "by [a] heating system professional.”

Nowhere in the article will you see DOE favoring any brands.

Instead, ask as many trusted friends, family members, and acquaintances as possible for recommendations. Look at Google and Facebook reviews (those are a little harder for companies to manipulate). Sites like Home Advisor and Angi (formerly Angie’s List) allow contractors to pay to be recommended so I don’t tend to rely on those. Meet with several contractors, have a few questions for them and listen intently to their replies.

A quality contractor should be confident in their recommendations without being pushy or using high-pressure sales tactics. They should be able to provide reasons for their recommendations and written assurance that they will use quality fittings and parts backed by the manufacturer instead of cheaper universal options. They should also be able to perform a load calculation which leads us into the next mistake.

Mistake #4: Choosing the Size

If you search for "proper sizing of an HVAC system", you could find tons of information online that encourages you to do it yourself. Yet when you attempt to do it on your own, it’s not as easy as some make it sound!

Sizing should be done by a HVAC professional. You'll find that energy.gov emphasizes the same this as well. Let your trusted contractor handle the tough job of measuring the load calculation for your unique home and choose the size furnace you need.

Even though it is tempting to simply DIY it, sizing is exceptionally crucial to your success in picking reliable and long-lasting equipment. 

If you make the mistake of purchasing a unit that is too small when buying a furnace, it will struggle to warm your living space. This will cause unnecessary and excessive energy consumption minus the comfort. Furthermore, it will cause excessive wear and tear to the equipment resulting in more repairs and a shorter lifespan.

If you try to overcompensate thinking bigger is better, you are still in trouble. An oversized furnace is not just more expensive upfront but could require pricey duct replacement to accommodate its size.

Another common drawback of a furnace that is too big is the constant short cycling. Since it is too big for the room you put it in, the unit can warm the area pretty quickly and prompt the furnace to turn on and off more frequently than it should. Needless to say, short cycling is bad for you and your furnace. Again this causes excessive wear and tear to the unit.

Your carefully chosen contractor should agree to include a performance guarantee in their contract. It should be stated clearly and verbatim that your contractor has calculated the correct size and will replace it for free if it turns out to be incorrect.

Mistake #5: Choosing All the Bells and Whistles

You may be impressed when the salesman tries to amaze you with the “state-of-the-art” features of a new furnace brand. Even though it may sound quite appealing, you could be setting yourself up for costly repairs down the line if you pick an overly complicated furnace.

Buying a furnace, whether gas, oil, or electric, has a singular and specific purpose. The way the furnace works is pretty simple as well. It is connected to a thermostat which dictates whether a room needs warming up. 

Furnace Salesman

If you set the thermostat to 70 degrees and the room’s temperature is lower than that, your furnace will kick start and commence the heating process. The cold air enters the return ducts, the furnace warms it up in the heat exchanger, and a blower fan distributes the hot air to your home. Once the thermostat level is reached, the furnace will automatically shut down.

Truly, the makeup and the processes of a furnace are indeed simple yet elegant. So, anything beyond this uncomplicated system is mostly unnecessary. As is true with most things now, there is always something “new and better” coming out. With a furnace though, simpler really is better.

The most common misstep homeowners make when buying a new furnace is choosing a two-stage or multi-stage over the basic single-stage furnace. We have an entire article discussing why two-stage furnaces are not worth the extra money for the following reasons:

  1. 1
    It is NOT more energy-efficient: It will cost you 11% more on your electricity consumption, according to ASHRAE (American Society of Heating Refrigerating and Air-Conditioning Engineers). The efficiency of a furnace will remain regardless of whether it is single or two-stage. 
  2. 2
    The noise level is NOT that different: New models of single-stage furnaces have been designed to be just as quiet as what the two-stage claims to be. 
  3. 3
    The comfort level is NOT that significant: Field testing results show that although a two-stage furnace can warm up a room in 10 minutes, a single-stage can produce the same result in 11 minutes. You would not even notice that difference. 

Moreover, an overly complex machine involves expensive, special-order parts. If and when your furnace requires repair or parts replacement, it could likely take longer to get your furnace up and running. The sad reality is parts are getting harder to find and shipping takes longer. A simple single-stage furnace is more likely to use parts that are in stock locally.

Robert Bradford


I'm Robert Bradford. I've been in the heating and air conditioning industry for 30 years. Ov​​​​​er 40 if you count the years I helped my father as a kid. On this site, I share everything I've learned about finding the best HVAC contractors and equipment for your home. I'm happy to say that over the last few years, The Comfort Academy has grown into a trusted site with thousands of informed site visitors each year.

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