We’ll be the first to admit: HVAC jargon can be very confusing. On the surface, heating and cooling equipment can seem quite simple. Adjust the thermostat, turn up the heat, get more heat… that’s it, right?
In truth, gas furnaces are quite complicated and have evolved extensively over the past 30-50 years thanks to advancing technology. To help our customers understand more about their own furnace system — and whether it’s doing its job or needs replacement — let’s take a look at one of the most common questions we get from our customers: “What does furnace efficiency mean?”
Gas Furnace Efficiency: An Overview
The indicator of efficiency that you’ll see most often is a percentage, such as “up to 80% efficiency.” But what does that actually mean?
Typically, this percentage refers to the AFUE, or “annual fuel utilization efficiency.” This rating attempts to gauge the real-world average efficiency of a furnace as opposed to an unchanging, scientific measure of “peak” efficiency. This means that this percentage becomes very relevant to the average homeowner who is looking to save money and be good to the Earth.
AFUE And BTUs, Oh My
To accomplish this, AFUE measures the amount of heating – energy – obtained from a given amount of fuel. This is measured in BTUs – another term you may have heard while doing your research. BTU, or the “British thermal unit,” is a unit of heat utilized as a standard measurement for HVAC equipment. (Technically, it’s the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Fun fact: it’s related to the calorie, a unit in the metric system!)
Back to furnace efficiency: what this generally means is that an 80% furnace produces 80 BTU of heat for every 100 BTU. A 95% efficient furnace produces 95 BTU of usable heat for every 100 BTU of fuel input, and so on.
Another way to word this: Think of a dollar bill. With an 80% efficient furnace, every time your furnace fires, 20 cents of that dollar goes “poof” while 80 cents goes to generating heat. For a 95% efficiency furnace, it’d be just a nickel.
So How Much Does Furnace Efficiency Matter?
It matters quite a bit — but not in the way you might be thinking. Many homeowners feel that more efficiency is better; it does make sense to think that! However, the proper furnace for each application can be quite different, and it also depends on your goals.
For example — if your goal is to be as environmentally-friendly as possible and the cost of either the equipment or its daily operation is not as much of a concern — you may be best going with the most efficient furnace you can.
However, depending on several factors such as the size of the home and the actual placement of the furnace, you may not achieve cost-reducing benefits by going with a more efficient furnace. Worded another way, it may turn out that an 80% efficiency furnace is the best balance of cost, ease of installation, and performance for your home as opposed to a 95% efficiency furnace.
How To Determine The Most Efficient Furnace For Your Installation
The best way to determine the right type and efficiency furnace for your home is to schedule a free estimate with one of our technicians. There is no trip cost for a new system estimate, and your technician will evaluate all the factors of your home (including where the furnace is placed, existing ductwork and other features of your HVAC system, your budget, and so on) to determine the best options for you.
Remember — with G&R you can also take advantage of our installation perks! While your technician is providing your new furnace system estimate, you’ll have the opportunity to review and choose the benefits best for you. This may include additional discounts, additional equipment such as a humidifier upgrade, or indoor air quality equipment. It may also include flexible HVAC financing, which can help you get the best heating system you need without having to compromise.