Should You Run Your Furnace on ‘Auto’ or ‘On’?

Setting the thermostat is always a bit of a balancing act.

On one hand, you want to keep your home cozy and comfortable as possible...but you’re well aware of the cost of heating your home, and you’re not one to spend frivolously!

You might’ve wondered whether it’s better to use the ‘Auto’ or ‘On’ setting on your thermostat. The answer to that question really depends on your personal needs and preferences – but when it comes to furnace efficiency, we do lean towards one more than the other.

Here’s what you should know about running your furnace on ‘Auto’ versus ‘On’ when it comes to comfort, energy-efficiency and the overall health of your home’s heating system.

What Does the ‘On’ Setting Do?

When you’ve selected the ‘On’ setting on your furnace, it means the furnace fan will be running all the time.

Advantages of the ‘On’ Setting

One of the primary benefits of the ‘On’ function is that it will continually cycle air through your HVAC filters, removing more contaminants from the air you breathe. So long as you’re switching out your air filters regularly, running the furnace on ‘On’ can help improve the quality of the air inside your home.

Drawbacks to the ‘On’ Setting

Leaving your furnace running 24/7 isn’t conducive to a lower energy bill! The abundance of air cycling through your furnace also means you may have to replace your air filters more often.

Plus, running your furnace all the time can backfire during the winter. The fan will keep running even when there’s no heat being produced, which at times causes cold air to circulate − a no-go during frigid Toronto winters!

What Does the ‘Auto’ Setting Do?

With the ‘Auto’ setting, your furnace fan runs when it receives a signal from your thermostat. This function is meant to maintain a set temperature, but not run continuously.

Advantages of the ‘Auto’ Setting

The fact is, when don’t leave your furnace running all the time, you waste far less energy and save considerable money as a result. Your air filters will also last longer, offering another form of savings.

Drawbacks to the ‘Auto’ Setting

If you own a high-end furnace, the system should last between 15 to 18 years to get a reasonable return on investment. Even a low-to-medium-end model should give you around 12 good years of use.

Unfortunately, there’s a concern that if you continue to stop and start your system, the wear and tear on your furnace can begin to add up. Starting and stopping any motor causes more wear and tear than leaving it running continuously. This can cause motor failure to occur.

Beyond that, the ‘Auto’ furnace function might cause disjointed air distribution when it initially turns on. Again, we can’t help but bring up the importance of an adequately warmed living space during Canadian winters! Your home is your castle, and the temperature should never reach uncomfortable levels.

There is one more way to mitigate issues with heat distribution throughout your home. An HVAC professional can finetune your furnace while balancing your ducts and vents, which results in even temperatures in all rooms.

‘Auto’ vs. ‘On’: The Final Verdict

While there are pros and cons to the ‘On’ and ‘Auto’ settings on your furnace, we tend to lean towards the ‘Auto’ setting.

Here's why.

When it comes down to the nitty-gritty, the damage done to your system by turning on and off often is negligible. Any of the problems can be mitigated with seasonal furnace maintenance performed by HVAC professionals, who can also help with any air distribution problems.

Plus, the energy savings are monumental when compared to what you’ll spend if your system runs continuously!