Updated: September 1st, 2022

We receive many calls from customers asking if they should upgrade from a 90% to a 96% efficiency gas furnace. There are a few factors to consider before making the change to a variable speed furnace. Let’s get into it.

Advantages and Disadvantages of Variable Speed Furnace

It’s important to have a high-efficiency furnace in your home to help protect yourself from high utility bills. A high-efficiency furnace has a rating of 90% or above. So, what does the 90% efficient rating mean? If a furnace is rated at 90% it means 10% of the energy used is lost, and 90% becomes heat.

If you have a 90% efficiency or above furnace that’s 10 years old or less, to upgrade to a 96% efficient furnace probably doesn’t make a lot of sense. Why? Because depending on the size of the furnace you’re looking at, you may only save $50 to $100 in energy costs per year. That’s almost nothing compared to the cost of a new furnace.

However, when you look at the overall energy consumption of a furnace, you need to look at how much gas it will use AND how much electricity will it use to move warm air through the house. What makes a difference in electrical consumption is the type of blower motor in the furnace.

Two Primary Types of Gas Furnace Blower Motors

Standard furnace motor

Many of the 90% efficient furnaces installed since the 1980s use a standard blower motor. Meaning the furnace only operates at one speed — typically fast — and provides a sudden, noisy blast of air. These motors are much larger than the motors used today to move warm air throughout your home … meaning they are not very energy efficient.

Variable-speed furnace motor

A variable speed blower motor runs at different speeds to precisely control the flow of heated air throughout your home. It constantly monitors the data coming from your heating and cooling system and automatically adjusts to meet your comfort needs. Plus, a variable speed motor gradually ramps up to full speed eliminating the sudden, noisy blast of a standard furnace motors. The best news … a variable speed furnace motor is 80–85% more efficient than a standard furnace motor.

Is Upgrading to a Variable Speed Gas Furnace Worth It?

If you are going to upgrade from a 90% to a 96% efficient furnace make sure it has a variable speed furnace motor, and you could enjoy energy savings of up to $400 a year. Otherwise it’s not worth the investment.

Let’s recap…

• If you don’t have a 90% efficiency or higher furnace in your home, then yes it may well be worth the cost to upgrade.

• Make sure the 96% efficient furnace has a variable speed motor, otherwise you will not recoup your investment.