Before you turn the heat on for the season, Fairfax County Fire and Rescue recommends a yearly professional cleaning and check of your heating system, at least three feet of clearance around furnaces, water heaters and space heaters, and carbon monoxide alarms on every level of your home. Heating equipment failures are one of the leading causes of home fires, according to the department.
Quick Summary
- Have a professional clean and check your heating system every year. The county’s CO guidance says to have gas furnaces and appliances inspected every fall.
- Keep paper, clothing, trash and other combustibles at least three feet from your furnace, water heater, wood stove or space heater.
- Install CO alarms on every floor, following the manufacturer’s instructions, and keep working smoke alarms on every level too.
- The county has a limited number of CO alarms for residents who need one, installed by the local fire station. Call 703-246-3801.
- Daylight saving time ends Sunday, November 1, 2026, a handy reminder to test every alarm.
In this post: The first cold night is a bad time to find out | Start with the furnace and water heater | Fireplaces and space heaters need their own attention | The alarm that goes with a gas furnace | What this means for Reston and Fairfax County homeowners | Sources and reporting limits | FAQ
The first cold night is a bad time to find out
Most of us do not think about the furnace until the first chilly morning. The system kicks on after months of sitting idle, there is a dusty smell for a few minutes, and we hope for the best.
Fairfax County Fire and Rescue would rather you run a short checklist first. Its heating systems safety page says heating equipment failures or malfunctions are one of the leading causes of home fires, and that a little preventive maintenance goes a long way.
3 feet: the minimum clearance the county recommends between combustibles and your furnace, water heater, wood-burning device or space heater.
Start with the furnace and water heater
Have a professional clean and check the heating system every year. The county says this may prevent a fire and will make the system more energy efficient. Its carbon monoxide guidance adds that a qualified technician should inspect gas furnaces and appliances every fall.
Then do the ten-minute part yourself. Look at what has crept up next to the furnace and water heater since spring. In a lot of Northern Virginia townhomes, the utility closet doubles as storage, and boxes drift closer over time. Clearing a three-foot zone is the easiest fix on this list.
Fireplaces and space heaters need their own attention
- Have a licensed chimney sweep clean and inspect a wood-burning chimney at least once a year.
- Use a glass or metal spark screen and install chimney caps.
- Never use gasoline, kerosene or lighter fluid to start or revive a fire.
- Put hot ashes in a covered metal container outside, well away from the house.
- Keep space heaters away from curtains, beds, clothes and children, with three feet of clearance, and turn them off when you leave the room or go to bed.
- Never refuel a heater while it is running or still hot, and choose one with an automatic shut-off if it tips over.
The alarm that goes with a gas furnace
Carbon monoxide is colorless, odorless and tasteless, which is why an alarm matters more than your nose. The county’s carbon monoxide alarm program page lists common sources: defective gas or oil furnaces and water heaters, cracked chimney flues, charcoal grills used indoors, a gas oven used to warm a room, a car running in an enclosed space, and a fireplace damper closed before the fire is out.
Put CO alarms on every floor and mount them according to the manufacturer’s instructions. Look for a UL label. The county says plug-in models last about 10 years and that alarms cost about $35 to $50 at local hardware stores. A CO alarm does not detect smoke, so keep working smoke alarms on every level too.
If a CO alarm sounds, get everyone out of the house at once and call 911 from a neighbor’s house. The county advises against stopping to open doors and windows. Firefighters will take readings to find the source.
If cost is a barrier, the county’s Public Affairs and Life Safety Education Section has a limited number of CO alarms for residents who need one, and a local station will install it. Call 703-246-3801 to ask.
About 10 years: the typical life of a plug-in CO alarm, according to Fairfax County. Check the date on the back of yours.
What this means for Reston and Fairfax County homeowners
Heating season is also when furnace age and service history come up in home inspections. If you are buying, it is reasonable to ask when the furnace and water heater were last serviced and where the alarms are. If you are selling, a recent service receipt and fresh alarm batteries cost little and answer a question buyers are already asking.
Fall is a busy maintenance stretch in general. Our guide to Fairfax County leaf collection covers the other big seasonal chore, the Reston neighborhood guide explains how housing types differ around town, and the Reston home value tool gives you a starting estimate if you are thinking about selling.
Sources and reporting limits
- Fairfax County Fire and Rescue, Heating Systems Safety, retrieved October 2026
- Fairfax County Fire and Rescue, Carbon Monoxide Alarm Program, retrieved October 2026
The county pages are older and do not show recent update dates, so confirm current guidance and alarm availability with the department. This post is general information and not a substitute for an inspection by a licensed technician. For emergencies, including suspected gas leaks, call 911.
FAQ
How often should a furnace be serviced in Fairfax County?
Fairfax County Fire and Rescue recommends a professional cleaning and check every year, and says gas furnaces and appliances should be inspected by a qualified technician every fall.
Where should carbon monoxide alarms go?
On every floor of the home, mounted according to the manufacturer’s instructions, with working smoke alarms on every level as well.
Can I get a carbon monoxide alarm from the county?
Fairfax County says it has a limited number of CO alarms for residents who need one, installed by a local fire station. Call 703-246-3801 to ask about availability.
What should I do if my CO alarm goes off?
Get everyone out of the house immediately and call 911 from a neighbor’s house. Do not stop to open windows.
Thinking about a move this winter and want a local read on the market? Reach out to Nikki Lagouros, Realtor, anytime.