The New Homeowner’s Guide to Home Heating - Part 2 — Furnace Deep Dive!

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When you were growing up, your parents probably taught you loads of things to prepare you for the future. Like how to brush your teeth. Do laundry. Bandage a skinned knee. Change a tire. Hammer a nail. Make a grilled-cheese sandwich. But they probably never talked to you about… maintaining a furnace.

We don’t blame the parents. They’ve got their hands overfull already. But the fact is that most first-time homeowners don’t know much about furnaces. Just ask the member of our marketing team who, for more than a year after buying her first home, didn’t once change the filter on her furnace (GASP). She didn’t know she had to. Nobody had ever told her — and why would they?

New homeowners, we are telling you now. This blog breaks down the basic things you need to know to keep that furnace running. We also talk you through if, when, and how to repair or replace your furnace. Finally, we even give you a short glossary, so you’ll know what you’re talking about. You’re welcome.

Understanding Your Furnace

No, we’re not sending you and your furnace to couples therapy. You don’t need to know your furnace THAT well. But it is helpful to understand its basic operation and most important components, as well as some of the many acronyms you’ll come across. Hence, welcome to a quick glossary focused on getting to know your furnace’s many interesting innards and what they’re up to. Of course, we’re not being exhaustive here — only giving the basics necessary to help you maintain, monitor, and upgrade your furnace as needed.

A Brief Glossary of Furnace Terms

  • AFUE: AFUE, or annual fuel utilization efficiency, is a percentage measure that indicates how much energy is being converted to heat. The higher the AFUE, the higher the furnace’s efficiency. For example, an AFUE of 98.5% means the furnace is using 98.5% of its fuel to heat your home, losing only 1.5% as exhaust.
  • BTU: The BTU, or British thermal unit, measures how much heat is given off when fuel is combusted. Most furnaces are labeled as providing a certain number of BTUs.
  • Blower motor and blower wheel: The blower motor moves the blower wheel, which is attached to the blower motor. Together, they move the air through your heating system.
  • CFM: CFM, or cubic feet per minute, is a unit used to measure the volume of airflow. More CFM isn’t always better; the right CFM is relative to the size of your furnace and your home.
  • Damper: In your ductwork, these valves help to control airflow. Opening and closing them changes how much hot air you let into your home through the vents from your ductwork.
  • Ducts or ductwork: These metal or synthetic passages channel heated air to the various rooms of your home. (In action movies, ductwork is often used to enact Clever Escapes from Bad Guys. Probably not workable in your home’s ductwork.)
  • EER: EER, or energy efficiency ratio, measures the relative efficiency of your furnace. It’s stated as a ratio of BTU output per hour to the watts of energy required to create that output. The higher the EER, the more efficient the unit.
  • Energy StarⓇ: If a furnace is labeled with the Energy Star logo, it means that the US Environmental Protection Agency (EPA) has determined that it is up to 15% more efficient than standard models. Think of it as a gold star from the EPA! (Or rather, a blue star. It’s blue.)
  • Filter: This removable device in the air intake portion of your furnace protects the motor, fan, and heating implements from dust. It also helps to improve your home’s air quality.
  • Heat exchanger: This is the big daddy, all-important component of your furnace. Air is heated as it passes over the hot metal surfaces of the heat exchanger. High-efficiency furnaces have two heat exchangers (primary and secondary); the secondary heat exchanger releases more heat to create water vapor, which — by virtue of some neat-o science we won’t bother to explain — further improves efficiency.
  • HVAC: HVAC (pronounced H-vack if you want to look like you have a clue) is an acronym for Heating, Ventilation, and Air Conditioning.
  • Load estimate or load analysis: This detailed analysis of your home’s heating needs helps professionals determine which type of furnace will best suit your needs.
  • Thermostat: This device, generally positioned on a wall in a central area of the home, controls the furnace, regulating the home’s temperature. Nowadays, most thermostats are programmable.
  • Variable-speed blower motor: This varies the speed of airflow over the heat exchanger. Systems with this feature can operate at a range of speeds, automatically and precisely adjusting airflow to maximize comfort and avoid temperature swings. Variable-speed motors also ramp up more gradually than single-speed models.

How Your Furnace Works

In case you missed this up in the glossary: Air is heated as it passes over the hot metal surfaces of your furnace’s heat exchanger, which is heated either by electricity or by combusting natural gas, propane, or oil. Then, your furnace blows the heated air through ductwork to warm the air throughout your house. A central thermostat regulates the temperature of your home by controlling your furnace.

Furnaces are only one option among many, many different types of home heating systems. Part one of Covered’s home heating guide describes the most common home heating systems, as well as their relative pros and cons. It just so happens that, at present, furnaces are still the most common home heating system in North America — hence our deep dive into helping you understand your furnace. Because chances are, that’s what you’ve got.

Maintaining Your Furnace

As a homeowner, it is your solemn duty to make sure your furnace is properly maintained. Sure, back when you were renting, it was rather glorious to consider the furnace *someone else’s problem*. But those days are gone. And your furnace will genuinely become a problem if you don’t maintain it.

Fortunately, maintaining your furnace isn’t difficult or complicated. You simply need to:

  • Replace your furnace filter regularly. We recommend sticking with the basic filters, as those fancy, expensive ones may actually restrict airflow too much, straining your blower motor. Replacing at least once every three months is a good rule of thumb, though folks with pets may want to replace more frequently. If you don’t replace your filter regularly, your furnace’s interior parts will end up dirty, restricting airflow and causing extra wear and tear on your system. It’ll also worsen the air quality in your home. Regular filter replacement is the most important part of maintaining your furnace.
  • Ensure annual inspection and maintenance. The easiest and best route is to hire someone to do this. Most HVAC businesses offer annual repair plans, or you can find a certified HVAC professional to do a one-off inspection and cleaning each year.
  • Make sure all HVAC repair professionals are licensed and certified. You could void your furnace’s warranty if you let someone who’s not certified repair your furnace. Trust us, your warranty is worth far more than the few bucks you might save by using someone who’s not certified.

What about DIY furnace maintenance and cleaning, you may ask It’s indeed possible to safely perform some furnace maintenance tasks yourself. Before you jump in, however, it’s important to understand:

  • DIY annual furnace maintenance is a difficult and potentially hazardous task. After all, you’re working with a machine that combusts flammable fuels. It’s also a considerable investment of time and labor. The consensus seems to be that, with the right tools and materials in hand it’ll take you at least three hours to complete the basic tasks required.
  • To ensure safety, you need to make sure you know what you’re doing. Fortunately, you’ll find countless DIY furnace maintenance resources on the internet. HomeAdvisor and This Old House both offer solid step-by-step guides, and YouTube offers a trove of helpful videos. Do your homework before you begin. If possible, consult your furnace manual for specifics.
  • Certified HVAC professionals will be able to do more than you can. They have tools, analytics, and technical expertise that you don’t.

Relighting a Pilot Light in an Old Furnace

How do you relight a pilot light in a gas furnace? This can be a common problem in older furnaces. (New furnaces use electric ignition.) YouTube is a good way to familiarize yourself with the practice, and The Spruce offers an excellent resource on the topic. In overview, here’s what to do:

  • If possible, follow the manufacturer’s instructions. They’ll have relighting instructions specific to your furnace. If you can’t find the booklet, try googling your furnace’s make and model number to find a PDF.
  • If you can’t locate the manufacturer’s instructions, try this:
    • Turn up your thermostat. You need your furnace to want to kick on.
    • Find the pilot gas valve. The valve will be located near the pilot light assembly, often near the base of your furnace.
    • Using your hand, turn off the valve. It’ll have a control knob with “on,” “off,” and “pilot” positions. Turn it to “off.”
    • Wait at least three minutes. This is crucial, as it lets the gas dissipate.
    • Turn the knob to the “pilot” position.
    • Attempt to relight the pilot. While pushing and holding the “reset” button, raise a lit match (ideally one of those long kitchen matches) or clicker lighter to the pilot opening. Keep holding the button till the pilot flame is again lit. When lit, slowly release the button.
      • If you have successfully relit the pilot light, turn the gas valve back to the “on” position. Wait to see if the pilot light remains lit.
      • If it did not ignite, wait a few minutes before repeating the process.
      • If you run into issues, consult The Spruce link above for a trouble-shooting guide.

Repair vs. Replace: How Do You Know?

All furnaces wear out eventually. There’s no getting around it. The question is, when is the right time to replace your furnace? And when can you get away with simply repairing it?

While every system and set of circumstances will be different, these repair vs. replace guidelines may be helpful:

  • Keep in mind that the average furnace lifespan is about 15 to 20 years. Some furnaces last well past 40 years, but yours may not be one of them. If your furnace is less than 15 years old, it’s likely that you can simply repair it.
  • When repairs are happening frequently (or with bigger price tags), it’s time to do a cost-benefit analysis. Furnace repairs can be costly. If your system is regularly in need of repair, it may make more sense to simply replace it — especially if it’s over that 15-year mark. According to Thumbtack, for furnaces more than 15 years old, experts recommend replacing instead of repairing when the cost of the repairs exceed one-third of the likely replacement cost. (We’ll get to those costs in a minute.)
  • Rising energy bills may signal a problem. Pull up your energy bills online and compare your heating costs year over year. If costs have gone up significantly, it may mean that your furnace is in need of repair… or, yes, replacement.
  • You don’t want to be stuck without a functioning furnace during the winter months. In addition to being way cold, you could end up with burst pipes, or paying a premium for an emergency repair call. That’s why summer or fall are the best time to be proactive about doing research and consulting with repair/replacement professionals. It’s all part of making sure your home is ready for winter.
  • Cracks or holes in the heat exchanger likely mean it’s time for replacement. Remember that big daddy, all-important component we talked about in the glossary? Over the years, given its continual expansion and contraction, your heat exchanger could crack, becoming unsafe. Again, if your furnace is under the 15-year mark, you may be able to simply replace the heat exchanger. Regardless, the crucial thing to understand is that a cracked heat exchanger may give off carbon monoxide. Which brings us to the following point…
  • Carbon monoxide alarms going off? You may be headed for replacement. If your carbon monoxide alarm was activated, start by following the advice of advice of alarm manufacturer Kidde, which includes getting everyone into fresh air immediately (and calling 911 if anyone is experiencing symptoms of carbon monoxide poisoning). Ultimately, you’ll also need to call a certified technician to investigate. And again, if your heat exchanger is the problem, replacement may be in the cards.

Understanding Likely Replacement Costs

So how much does it cost to replace a furnace? Trying to figure out how much it’s going to cost to buy a new furnace and have it installed can be a squirrelly process. Different HVAC companies may charge different prices for the same furnace. The price of installation may vary widely based on where you live, the time of year, how easy/hard your furnace is to access, and how many modifications (e.g., new ductwork) are required to get the new system functioning.

Both Thumbtack and HomeAdvisor offer good, regularly updated resources to help you anticipate likely costs. Estimates provided are based on actual furnace replacement costs as reported by site members. Going with nationwide averages, HomeAdvisor gives the following ranges for the total cost of replacing and installing a new furnace:

  • Gas: $2,000 to $10,000
  • Electric: $1,200 to $7,000
  • Oil: $4,500 to $7,000

Getting Free Consultations from Certified Installers

Yes, that really is a whole lot of grey area when it comes to furnace replacement costs. Which is why your best bet is simply to start gathering quotes from certified HVAC installers in your area. Why?

  • Consultations are free. This is industry-standard practice. If they want you to pay for a consultation, call someone else.
  • Consultations are highly informative — and no-obligation. The installer’s representative(s) will schedule a time to come out to your home, do an analysis of your home’s energy needs, and make on-the-spot recommendations on furnaces that are right-sized for your home. They will provide total costs for the different options and talk to you about warranties, included services and maintenance, and so on. Most HVAC installers will even include the costs of any required building permits in their estimates. Of course they’re hoping you’ll decide to buy a furnace from them. But you’re under no obligation to do so.
  • Once you’ve gathered a few estimates, you’ll be well-positioned to make the right choice for your home and budget. As GI Joe always said, “knowledge is power” and “knowing is half the battle.” So get at least two or three estimates. Compare the recommendations and ask questions as needed. Don’t disappoint ol’ GI Joe by accepting the very first estimate that comes your way.

How should you find certified HVAC installers in your area? HomeAdvisor or Thumbtack are both good places to start, as they both offer tools letting you quickly request estimates from local installers. (Just use the links above.) Alternately, you can research reviews on the various sites (e.g., Google, Yelp, BBB) and select a few yourself, calling or emailing directly to request estimates.

Evaluating Your Furnace Estimates

Don’t just go by price. Make sure the furnace you choose fits your home, budget, and circumstances in terms of:

  • Efficiency. You can save on energy costs by going higher-efficiency. (At minimum, go with an EPA-certified Energy Star model.) But if you don’t plan to stay in your home longer than five years, your savings may not let you recoup the higher initial cost of that high-efficiency furnace. That said, a high-efficiency furnace can also be an attractive feature for prospective homebuyers.
  • BTUs. Make sure the furnace is right-sized for your home. Hopefully, your estimates should align with one another on BTUs, given all installers should be doing load analyses. If something seems off, you can come up with an estimate yourself for the sake of comparison.
  • Warranties. All furnaces will come with some sort of warranty. Most units will come with both a manufacturer’s warranty and a warranty from the installer. But warranties can be quite different from one another in terms of duration, scope (e.g., parts, labor), and services. What matters most to you?

Navigating the Different Furnace Brands

Last but not least, what brand of furnace should you buy? This, too, can feel like a heckuva lot of grey area for the new homeowner navigating furnace replacement. Are the differences between brands really significant? How do you know what’s right for you?

Different HVAC installers work with different manufacturers. Some may offer one brand exclusively; others may offer a range of brands. When you collect your free estimates, you’ll likely be presented with a range of furnaces from different brands. So what are the key things to understand?

  • Pricing varies widely from brand to brand. For example,for brands like Carrier, Trane, Lennox, and American Standard, both the furnaces and the installation tend to cost more.
  • Some furnace brands are made by the same manufacturers. For example, Day & Night is made by the same company that makes Carrier. Amana, Daiken, and Goodman are made by the same manufacturer. Rheem and Ruud are made by the same manufacturer. You get the idea. All this to say, some of these furnaces share the same essential components, but the bigger-name brands cost more. Opinions vary on if/how these differences pan out in terms of performance.
  • Though reliability varies greatly from brand to brand, some brands do rise to the top. Based on subscriber feedback, Consumer Reports calls Ruud, Trane, and American Standard the most reliable brands. Using research and expert opinions, goes with Trane as most efficient, Ruud as most reliable, and Goodman as the best budget option. (Notably, however, Consumer Reports calls Goodman a “less reliable” brand.) Of course, there are dozens of brands we haven’t named here that are absolutely worth considering.

And there you are. Now, you know pretty much everything you need to know to navigate the world of home heating, furnace maintenance, and determining whether to repair vs. replace your furnace. Your parents would undoubtedly be very proud. We’re proud of you, too.

Parents didn’t teach you the ins and outs of insurance, either? Don’t worry — get Covered! Give us a call at (833) 487-2683, or send us a message. We’ll be happy to answer your questions.

Cover Photo by Alex Perz on Unsplash