Why Should I Purchase a Variable-Speed Gas Furnace?

Why Buy a Variable Speed Heater

How often have you reached for a blanket or sweater only to take it off again when the gas furnace turns back on?  Are you looking for steady, warm and cozy indoor air that helps to eliminate the wavering chill in your home during the coldest months of the year?  The answer may be more straightforward than you think! Simply, ask your local HVAC dealer to install a high-efficiency, variable-speed, modulating gas furnace.


Heating with Variable Speeds


When your thermostat or HVAC control system calls for heat, the gas valve on your gas furnace opens, and the burners ignite. This ‘combustion of fuel’ is used to heat the air pulled in from inside your home. However, to get that heated air distributed to rooms in your house, it needs a little push.  This is where the variable speed blower motor comes in. It delivers…literally!

The ‘variable speed’ is a specific type of blower motor located in the gas furnace that moves the air into your ductwork, through room vents, and into your indoor spaces.  The variable speed blower motor operates at ‘various’ speeds to precisely control the amount of airflow directed throughout your home. It can start up slow and continue operating at a low speed when the heating demand is low, or kick into high gear on the coldest days of the year to provide cozy indoor warmth. A gas furnace with a variable speed blower motor allows for a more constant stream of heated air, providing enhanced levels of comfort in your home.  

Some modulating, variable speed gas furnaces are designed to maintain the indoor temperature to within a degree of your thermostat’s set point. That’s because the variable speed gas furnace does not wait for room temperature to dip to a dramatically low level before cycling back on. As a result, you may feel a more consistent room temperature with a modulating, variable speed gas furnace. Of course, your results may vary depending on the energy-efficiency of your home, insulation variables,  and the design of your central heating system. 

The variable speed gas furnace may operate for extended periods of time when compared to a single-speed model, but at lower speeds. This may also allow more time for the circulating air to interact with filters or additional air quality system components. However, as with traditional systems, it is essential to change out your filters according to your HVAC dealer or manufacturer’s recommendation.


Energy-Efficiency Heating


If you are concerned about energy-efficiency heating, you may want to consider a gas furnace equipped with variable speed technology. Unlike single-speed gas furnaces that operate at a full 100%  ON or OFF, a variable-speed gas furnace is designed to precisely adjust output to achieve maximum efficiency and comfort. If your indoor spaces don’t need a 100% of high heat every day of the heating season, the system may save energy use by starting up and/or operating at the lowest possible speed to keep a steady, comfortable temperature in your home. This can often eliminate that “cold start” feeling associated with a single-speed heating system. 

But can low, slow and steady heat delivery actually save energy? According to the Office of Energy Efficiency & Renewable Energy, a variable-speed motor running continuously at a half-speed may use up to 75% less power than a single-stage motor uses to move the same amount of air.1 When your home heating system uses less energy, that may equate to tangible savings on your monthly utility bill.

When paired with a modulating valve feature that regulates the amount of fuel burned, your gas furnace is designed to produce just the right amount of heat to match demand. The modulating function can be compared to the gas burner on a stove. If you need to keep your deliciously prepared dinner warm, you wouldn’t need to keep the flame on HIGH. The same goes for indoor heating. Once a room is up to temperature, the modulating gas valve and variable speed option may reduce output to keep your indoor spaces at the set temperature.  Since the fan and burner may not need to run at full capacity, the energy-spikes of on/off cycling may be eliminated. In short, a modulating or multi-speed gas furnace is designed to operate at the lowest speed to achieve the indoor temperature that you prefer in your home.

So if you cozy up to reduce energy-usage and increased comfort when the outdoor temperatures are falling, it may be time to invest in a variable speed, modulating gas furnace.


1 Office of Energy Efficiency & Renewable Energy. Variable-speed, low-cost motor for residential HVAC systems. n.d. https://energy.gov/eere/amo/variable-speed-low-cost-motor-residential-hvac-systems. 1 May 2017.