Snow and Ice Around Furnace Vents: A Winter Check Worth Making
After a Minnesota snowstorm, you clear the driveway, shovel the steps, and dig out the mailbox. But have you checked the furnace vents?
Snowdrifts and ice can obstruct outdoor intake and exhaust openings. Those openings play an important role in furnace operation, and keeping them clear belongs on your winter maintenance list.
Know where your furnace vents terminate
Many high-efficiency gas furnaces have plastic vent pipes that terminate through an exterior wall. In a two-pipe arrangement, one pipe brings outdoor air to the furnace for combustion, while the other carries exhaust gases outdoors.
Other systems use different arrangements, including roof terminations or combined intake-and-exhaust fittings. Do not assume every pipe outside your home serves the furnace.
If you are unsure which openings belong to your heating system, ask your HVAC service provider to identify them before winter.
Why an obstruction matters
A furnace needs an adequate combustion-air supply and a clear exhaust path to operate properly.
Snow or ice blocking an opening may interrupt operation or cause a safety shutdown. An obstructed exhaust can also create a carbon monoxide hazard.
A shutdown should not be treated as an inconvenience to override. If the furnace stops working or repeatedly attempts to restart, arrange professional service rather than repeatedly resetting it.
Check after storms—and drifting snow
A vent that was clear yesterday may become obstructed overnight.
Wind can push snow against the house, and snow removed from driveways, decks, or walkways can accumulate near vent openings. Falling or sliding roof snow may also cover previously clear terminations.
From a safe ground-level position, look for:
- Snow covering or approaching the openings.
- Ice buildup narrowing a vent termination.
- Damaged, loose, or displaced piping.
- Repeated icing in the same location.
Include these openings in your checks after significant snowfall, blowing snow, and periods of extreme cold.
Clear loose snow gently
Where safely accessible, gently brush away loose snow around the openings without pushing it into the pipes. Keep shoveled and blown snow away from the area.
Avoid striking the piping with a shovel, chipping at attached ice, or using an open flame to thaw a termination. If ice cannot be removed gently, or the opening is difficult to reach, contact a qualified HVAC professional.
Do not add a homemade cover, screen, elbow, or pipe extension. Changes to a vent termination can affect airflow and must comply with the equipment manufacturer’s requirements.
Recurring ice needs more than repeated clearing
If ice repeatedly obstructs an opening, have the venting evaluated.
A technician can check the termination arrangement, pipe slope, drainage, and installation requirements. The appropriate solution depends on the equipment and site conditions.
There is no single clearance measurement that applies to every furnace installation. Required clearances and provisions for expected snow accumulation must follow the applicable equipment instructions and installation requirements.
Keep carbon monoxide protection in place
Carbon monoxide is colorless and odorless. You cannot rely on smell to determine whether exhaust gases are entering your home.
Maintain CO alarms according to their instructions. If a CO alarm sounds or you suspect carbon monoxide exposure, get everyone outside immediately, call 911 from outside, and remain out until emergency responders say it is safe to return. Do not delay leaving to inspect or clear a vent.
What a home inspection can identify
A home inspection may identify visible concerns with accessible vent piping and terminations, including damage or an obstruction present during the visit.
It does not predict future snowdrifts or establish how the equipment will perform through every winter condition. Ongoing maintenance and professional servicing remain important after the inspection.
Buying or selling a home in the Twin Cities? Learn more about Inspecta-Homes’ inspection services at inspectahomes.com.
