Quick answer: Many Centennial Hills homes have the furnace in the attic, where it sits through months of summer heat and dust before the first cold night. Before the northwest valley’s colder mornings arrive, replace the filter, look at the drain pan and condensate line, check that the flue cap on the roof is still in place after wind, and run the heat for a full cycle while you are home. If you see water, smell gas or the furnace shuts off early, call a technician instead of climbing around the unit.
Centennial Hills sits at the northwest edge of the Las Vegas Valley, at a higher elevation than much of the city. Clear desert nights there often run a few degrees colder than in central Las Vegas, so the heat tends to come on earlier in the season. In many of the neighborhood’s two-story and newer single-story homes, the furnace or air handler is installed in the attic. That location saves floor space, but it also means the equipment spends the summer in one of the hottest spaces in the house and is easy to forget about until the first chilly morning.
Why this matters in the next few weeks
The National Weather Service forecast for Las Vegas this week calls for sunny afternoons around 70 degrees, lows in the 50s and a breezy stretch late in the week. That mild window is the best time to look over an attic furnace. Once nights in the northwest valley drop into the 30s and 40s, a problem found at 6 a.m. is harder to live with, and service calls get busier across the valley.
1. Change the filter, and find out where it actually is
With an attic furnace, the filter is usually in a return grille on a ceiling or hallway wall, but some installations also have a filter slot at the unit itself. Check both places if you are not sure. A filter that loaded up with summer dust and pollen restricts airflow when the heat comes on, and restricted airflow is a common reason a furnace overheats and shuts itself off. Write the filter size down so the next change is quick.
2. Look at the drain pan and condensate line
Attic air handlers and high-efficiency furnaces have a drain line, and most attic installs sit over a secondary drain pan. Summer cooling can leave that pan with sludge, dust or standing water. From a safe spot on the attic platform, use a flashlight to look for water in the pan, rust stains or a float switch that has tripped. Stains on the ceiling below the unit are also a warning sign. Water problems in an attic can cause ceiling damage, so have a technician clear the line rather than forcing it with chemicals or a wet vac pushed deep into the fittings.
3. Check the roof vent after windy days
Gas furnaces vent combustion gases through a flue pipe that exits the roof. Strong spring and fall winds in the northwest valley can loosen or knock off a vent cap. From the ground, use your phone’s camera zoom to see that the cap is still on and the pipe is straight. Do not walk on a tile roof to check. If the cap is missing or bent, schedule service before running the furnace for long periods, and keep a working carbon monoxide alarm on each sleeping level.
4. Make the attic safe to work in
A technician needs a clear path and a stable place to stand. Before a visit, make sure the attic hatch opens, the pull-down ladder is sound, there is a light that works and nothing is stored on the walkway or against the furnace cabinet. Holiday decorations and boxes stacked near an attic furnace are a fire and airflow concern and slow down every service call.
5. Run a full heating cycle while you are home
Pick a cool evening, set the thermostat a few degrees above room temperature and stay nearby for 15 to 20 minutes. A brief dusty smell on the first run can be normal. Note whether warm air reaches every room, whether the system runs until it reaches the setting and whether you hear new banging, squealing or repeated clicking from overhead. Turn the system off and call if you smell gas, see smoke or the smell does not fade.
When to call instead of checking it yourself
- Water in the drain pan, a tripped float switch or new ceiling stains.
- The furnace starts and shuts off within a few minutes, over and over.
- A gas smell, a carbon monoxide alarm or a missing flue cap.
- Some rooms stay cold while others warm up normally.
- The attic is too hot, cramped or unsafe for you to reach the unit.
For background on safe heating and carbon monoxide alarms, see the U.S. Consumer Product Safety Commission’s carbon monoxide guidance.
Frequently asked questions
Why are so many Centennial Hills furnaces in the attic?
Many homes in the area were built with the furnace or air handler in the attic to save closet and garage space. It works well, but the unit is out of sight, so filter changes and drain checks are easy to miss.
Is it colder in Centennial Hills than in the rest of Las Vegas?
Often, yes. The neighborhood sits higher on the northwest side of the valley, and clear winter nights there commonly run a few degrees colder than in central Las Vegas, so heating starts earlier.
Can water from an attic furnace damage my ceiling?
Yes. A clogged condensate line or full drain pan can overflow onto the ceiling below. Have the line cleared if you see water in the pan or new stains.
Should I get my attic furnace tuned up before winter?
A yearly heating tune-up is a good idea, especially for attic units. Our $89 furnace tune-up is available through November 30, 2026.
Heating help for Centennial Hills homes
32 Degrees AC & Furnace Repair works with homeowners across Centennial Hills and the rest of the Las Vegas Valley. Our furnace maintenance visit includes a look at the filter, drain, venting and safety controls on attic units, and the $89 furnace tune-up price is good through November 30, 2026. Call 702-635-9505 or request a visit. We explain what we find and get your approval before any repair work. NV Lic. #88234.
Written by Junior Petersen, owner of 32 Degrees AC & Furnace Repair.