January 23, 2026

By Rena Wallingford

Colorado’s flirtation with warm winter days never lasts. Before the next deep freeze hits, now’s the time to tackle home maintenance that can keep you from shivering—or scrambling for emergency repairs.

Some furnace tasks are easy and oddly satisfying, like swapping out air filters or clearing vents. Others are best left to professionals, especially if it’s been a while since your last inspection.

“The first step is making sure your system is actually up and running,” says Jason Vela, general manager at Blue Valley Heating & Cooling in Longmont. “Turn the heat on and confirm that it starts and circulates air throughout the house.”

Below, Vela shares seven practical tips to get your furnace winter-ready, whether you’re handling basic upkeep or wondering if it’s time for an upgrade.

1. Fire it up and confirm everything works

Before temperatures plummet, turn on your furnace and make sure warm air flows evenly throughout your home.

“Inspect your furnace and clean all critical parts to remove dirt and dust,” Vela says.

During a professional maintenance visit, HVAC technicians handle tasks most homeowners wouldn’t know how—or want—to do: inspecting the heat exchanger for cracks, checking the blower and motor for buildup, and examining the burner and flame sensor to reduce the risk of carbon monoxide leaks.

For natural gas furnaces, the most common type in Colorado, technicians also check for gas line leaks and adjust pressure to ensure your system heats efficiently and safely.

2. Check and replace air filters regularly

“In general, we recommend replacing air filters at least every three months,” Vela says. “But it’s smart to check them monthly.”

How often you’ll need a replacement depends on the filter type, your home size, and your lifestyle. Thin filters clog faster, while washable versions may last a year. Homes with pets, allergy sufferers, or HVAC systems running year-round will need more frequent changes.

A dirty filter restricts airflow, forcing your furnace to work harder—raising energy bills and shortening the system’s lifespan.

3. Keep the furnace area clean and clear

Keep the area around your furnace free of clutter, dust, and flammable materials. This reduces debris entering the system and lowers fire risk.

“Make sure nothing is blocking your indoor or outdoor vents,” Vela says. Clear airflow helps your furnace run more efficiently—and safely.

4. Verify your thermostat reads accurately

Place a thermometer next to your thermostat and compare readings.

“If they’re more than three degrees apart, it’s worth having the thermostat checked,” Vela says.

An inaccurate thermostat can cause your furnace to cycle unnecessarily, driving up energy costs. For optimal efficiency, aim for 65 to 68 degrees during the day, lowering the temperature at night or when no one’s home. Layering up is far cheaper than fighting your utility bill.

5. Watch for warning signs your furnace isn’t running safely

“A properly operating furnace should burn a blue flame,” Vela says. “If the flame is yellow or flickering, that can indicate a problem.”

Also pay attention to unusual smells, rattling or banging sounds, rising energy bills, uneven heating, or frequent repair calls—all signs your system may need professional attention.

“If your furnace is more than 15 years old, it’s time to start watching closely for replacement warning signs,” Vela says.

6. Don’t skip fall maintenance—but winter isn’t too late

Fall is the ideal time for furnace servicing, before cold weather forces your system into constant use. But if you missed that window, it’s still worth scheduling a checkup.

Routine maintenance can cut energy costs by as much as 30 percent and helps technicians identify issues early—before a breakdown leaves you without heat on the coldest night of the year.

7. Remember: Denver’s altitude changes everything

“At Denver’s altitude, gas furnaces must be tuned precisely for proper combustion and airflow,” Vela says. “Otherwise, you lose efficiency and risk safety issues.”

Details like ductwork design, gas pressure, and venting matter more than many homeowners realize. Smart thermostats can help, and upgrades such as two-stage or variable-speed furnaces—or dual-fuel systems that combine a heat pump with gas—can dramatically improve comfort and efficiency.

Just keep this in mind: Even the best equipment won’t perform well if it’s improperly installed or incorrectly sized for your home.