Why won't my furnace shut off? Pippin Brothers, Lawton, OK
January 31, 2013

It has been bothering you for awhile. 

You know it’s time to replace your furnace because it’s past its prime. Every winter your heating bill is far too high and expensive repairs have been piling up.

So now it’s time to buy a brand spankin’ new furnace that will save you a ton of money through energy efficiency.

So, how do you determine if a furnace is energy efficient? Easy, look at its AFUE rating.

What is the AFUE rating?
AFUE stands for annual fuel utilization efficiency. It tells you in a simple percentage how efficiently a furnace uses its fuel to heat your home.

For example: Older furnaces have efficiencies as low as 55%. Today’s minimum standard for furnace AFUE rating is 80%. That means out of all the fuel you’re paying to heat your home, 55% or 80% is actually heating your home, and the other 45% to 20% is lost up the chimney or flue pipe respectively.

Bottom line: The higher the AFUE, the more efficient it will be, which means less of your money wasted as long as it is installed properly and your existing duct system is adequate.

Converting the AFUE rating to cash
To help you visualize how much money an energy efficient furnace saves you, think of the AFUE rating as the number of cents out of every dollar you spend on heating that’s actually heating your home.

Example: AFUE rating of 80%=$0.80 out of every dollar you spend on heating heats your home.

The other $0.20 is wasted due to inefficiencies with the furnace.

Therefore, less efficient furnaces need to run longer to produce the heat needed to meet the temperature setting you’ve set on your thermostat. And that’s why your old furnace skyrockets your heating bill.

Calculating long term savings with the AFUE rating
So what AFUE rating should your new furnace be? Well, that depends on you.
Consider your furnace’s current AFUE rating and how much of a budget you have for upgrading.

Higher efficiency furnaces cost more initially, but you can get a high return on savings in the long run if you have an older furnace.

To help you out, here is a handy chart from Energy.gov. It shows you how much money you can save from upgrading from one AFUE rated furnace to another:

As you can see, upgrading from an older furnace with an AFUE of 60% to a newer 95% AFUE rated furnace reduces your bill $37.80 for every $100 you spend on heating. That’s some significant savings over the lifetime of a furnace!

Use this chart to create a quick cost benefit analysis. Don’t buy a super high efficiency furnace if the savings won’t pay back over the lifetime of the furnace (probably 15 to 20 years). It doesn’t make economic sense.

Efficiency isn’t everything – Bigger is not better
Obviously energy efficiency is important when choosing a furnace. But you also need one that’s sized to fit your home. Too small and it won’t comfortably heat your home. Too large and you’ll be paying more in energy than you need to.

Most homes have furnaces that are too large. They are actually capable of heating your house and half you neighbor’s house. Bigger furnaces cost more to buy and operate. Also, don’t forget to consider that may of today’s furnaces come with energy efficient variable fans that can save you hundreds of dollars in electricity costs over and above the gas savings.

Airflow and delivered heat IS EVERYTHING!
It does not matter what brand or model furnace you purchase if it is not installed properly. While the furnace is the most expensive component in the heating system, it is also the least important.

The most important day in the life of a new furnace is the day it’s installed. Combustion efficiency, gas pressure, air mixture, and airflow are critical to your new furnace operating safely and at peak efficiency to ensure your comfort and the longevity of the equipment.

Variable capacity furnaces can make your home more comfortable
You existing furnace is probably a single-stage furnace. It has one setting when it operates regardless of the outdoor and indoor temperatures. It runs at full capacity whether you need it to do so or not.

New furnaces can have two, three and even unlimited modulating capacity settings that all function automatically through the thermostat. What this means to you, is that your home will maintain a more even temperature throughout the whole house, and you will be more comfortable in every room.

Contact Pippin Brothers, and we’ll help you pick an energy efficient furnace that’s within your budget and perfectly sized for your home with the features to achieve your desired level of comfort.