The Overlooked Winter Prep Step That Pays Off Big

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Don’t Forget Your Furnace Filter: A Small Step That Saves Big This Winter

It’s that time of year again. The mornings are cooler, the days are shorter, and before long, your furnace is going to be working full-time to keep the house warm. Before the season kicks off, here’s one simple reminder that makes a huge difference: replace your furnace filter.

A dirty furnace filter doesn’t just block dust. It strangles airflow. That means your blower fan and furnace have to work harder and longer to deliver the same comfort.

The U.S. Department of Energy estimates that a clogged filter can increase your HVAC energy use anywhere from 5% to 15%. That may not sound like much at first—but let’s translate those percentages into actual watts, BTUs, and dollars.

What Dirty Filters Really Cost in Energy

Let’s take an example home:

  • Furnace blower motor: 500 watts average draw
  • Furnace runtime during heating season: 1,000 hours (pretty typical in many climates)

That means your blower alone uses:
500,000 watt-hours, or 500 kWh per season.

Now add in the rest of the furnace system (controls, ignition, fans cycling more often, etc.) and it’s safe to assume a baseline of 600 kWh per heating season.

With a Dirty Filter:

  • 5% increase = +30 kWh (about 102,000 BTUs)
  • 15% increase = +90 kWh (about 307,000 BTUs)

What That Means in Cash

Using the U.S. average electricity price of about 15¢ per kWh:

  • At +30 kWh → $4.50 extra per season
  • At +90 kWh → $13.50 extra per season

That’s just the electricity side. A restricted filter also causes your furnace’s heat exchanger to run hotter and less efficiently, which translates into wasted gas if you have a gas furnace. For many households, that waste is another $15–$40 per season in fuel costs.

So in real-world dollars, a dirty filter could quietly drain $20 to $50 every winter.

And here’s the kicker: a new furnace filter typically costs $10–$20. One change pays for itself in a single season.

The Long-Term Payoff

Most furnaces last 15–20 years. If you let dirty filters run every winter, you’re talking about:

  • 300–900 kWh wasted over the life of the system (that’s 1–3 million BTUs!)
  • $300–$700 in wasted utilities
  • Added wear that could shorten the furnace’s lifespan or lead to expensive repairs

Bottom Line

It’s not just about clean air. Changing your furnace filter is one of the simplest, most cost-effective maintenance steps you can take. Fresh filters keep your system efficient, your bills lower, and your home more comfortable.

So before this winter kicks into gear, go ahead and swap in a clean filter. Your furnace (and your wallet) will thank you.

Premier Mechanical – www.claimyourcomfort.com – 720.207.6812

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