Why Your Furnace Works Harder in December (and How to Give It a Break)

Furnace

Dec 3

By Obsidian Heating & Cooling - Your Trusted Ankeny & Des Moines Metro HVAC Pros

December in Iowa isn’t just winter, it’s deep winter. The kind where the wind cuts sideways, you scrape frost off both sides of your windshield, and your furnace earns every bit of its keep. And if your furnace has felt like it’s running nonstop lately… that’s because it is.

But before you panic that it’s about to quit on you, take a breath. A hardworking furnace in December is totally normal, as long as it’s working efficiently.

Let’s break down why Iowa furnaces hustle harder this month, and how you can help yours take a well-deserved breather.

1. Iowa’s Deep Cold = Longer Heating Cycles

When outdoor temps sit in the teens (or drop below zero), your home loses heat much faster. Even newer homes feel the strain.

Your furnace must run longer to maintain the same indoor temperature you had in October. This doesn’t mean it’s failing, it’s simply doing its job.

Quick tip:
Try lowering your thermostat 1–2 degrees from your normal setting. A tiny adjustment can save run time and energy without noticeable comfort loss.

2. Wind Chill + Older Iowa Homes = Heat Loss

Older homes in Des Moines, Ankeny, Altoona, or Pleasant Hill often have:

Drafty windows
Leaky ductwork
Poor attic insulation
Cold basements pulling heat downward

When wind whips around your home (hello, Iowa!), your furnace works twice as hard to counteract heat loss.

Quick tip:
Don’t crank the thermostat. Instead, seal drafts, close unused basement vents, and add weather stripping where needed.

3. Holiday Hosting Adds Stress to Your System

In December, your home might see:

More people coming in and out
Doors opening constantly
Extra cooking heat
Added humidity from showers and baking
Christmas decor blocking vents (yes… this happens)

All of this temporarily throws off your home’s comfort balance.

Quick tip:
Walk the house and make sure furniture, trees, and decorations aren’t blocking vents or returns.

4. December Air Is Dryer, You Feel Chillier

When humidity drops, the air feels colder than it is. Your home at 70°F may feel like 67°F because dry air pulls moisture from your skin.

Your furnace runs longer to keep you comfortable.

Quick tip:
If you have a whole-home humidifier, bump it to 30–35%.
If you don’t, Obsidian can install one.

5. Your Furnace Might Need a Tune-Up

If your furnace hasn’t been cleaned or inspected since last winter, the December workload can expose hidden issues:

Dirty burners
Weak flame sensors
Low airflow
Dirty filters
Worn parts

Even minor problems cause longer cycles and higher bills.

Quick tip:
If your furnace runs constantly but your home isn’t warming properly…it’s time to call Obsidian Heating & Cooling for a diagnostic check.