Furnace Exhaust Was Buried in Snow: Now Cleared but Still No Heat? Essential Steps to Restore Your Heating

If your furnace exhaust was buried in snow and, even after clearing the vent, your furnace doesn’t start running again, you’re not alone. Many American homeowners face this challenge during heavy winter storms. This guide explains what happens when a furnace exhaust vent is blocked by snow, reasons why heat doesn’t return after clearing the vent, and step-by-step solutions to restore warmth safely and efficiently.

Understanding Your Furnace Exhaust System

The furnace exhaust system expels dangerous gases like carbon monoxide safely outside your home. When snow or ice blocks the vent, it can trigger safety mechanisms that shut the furnace off, protecting you and your family.

• Blocked vents can cause pressure sensors to shut your furnace down automatically.
• Even after clearing snow, some furnaces may require a manual reset or further troubleshooting.
• It’s crucial for safety and functionality to keep vents accessible at all times during winter.

Immediate Effects Of A Blocked Furnace Exhaust

When the furnace exhaust vent is blocked, your furnace often enters a lockout mode. This protects against the risk of carbon monoxide buildup inside your home. Here’s what commonly happens:

Symptom	Likely Cause	Required Action
Furnace Won’t Start	Vent Blocked or Still Sensing Danger	Clear Vent, Reset Furnace
Blowing Cold Air	Lockout Mode Triggered	Check For Error Codes, Reset
Repeated Shutdowns	Sensors Still Blocked or Wet	Dry Out & Inspect Sensors

After Clearing The Snow: Why Is There Still No Heat?

Even after physically clearing your furnace intake or exhaust vent, there are several reasons why your furnace may stay off:

• Safety lockout hasn’t automatically reset and needs manual intervention.
• Sensors may be wet, dirty, or damaged from prolonged snow exposure.
• There is residual ice or snow inside the vent piping that blocks airflow.
• Electrical components or the control board may require a reset.
• A fuse or circuit breaker may have tripped when the furnace was overloaded.

Step-By-Step Guide: What To Do If Your Furnace Won’t Start After Clearing Snow

Step 1: Confirm All Vents Are Completely Clear

Inspect both the intake and exhaust pipes for any remaining snow, ice, or debris. Carefully check inside the pipe ends; sometimes ice remains lodged inside even after the outside looks clear.

Step 2: Look For Frost Or Moisture On Furnace Sensors

Furnaces often have pressure switches or flame sensors that can be affected by excess moisture. If possible, gently dry these parts using a soft cloth. Do not use excessive force, and never pour water or liquid onto any parts.

Step 3: Reset Your Furnace Safely

Most modern furnaces have a reset procedure. Common methods include:

• Turning the thermostat to OFF, waiting 30 seconds, and then turning it back to HEAT.
• Switching the furnace power off at the main switch or breaker, waiting a minute, then turning it back on.
• Some furnaces have a dedicated reset button—check your furnace manual for guidance.

Step 4: Check For Error Codes On The Furnace

Modern furnace control boards often display a blinking light or digital error code. Your owner’s manual or the sticker inside the service panel provides a key to these codes. Common codes indicate lockout, pressure switch issues, or blocked vent sensors.

Step 5: Inspect Your Thermostat

Double-check that the thermostat is set to “HEAT” and the temperature is set above the current room temperature. Replace batteries if it’s a battery-powered unit, as sudden cold can drain them quickly.

Step 6: Ensure Power And Gas Supply

Make sure the furnace’s circuit breaker isn’t tripped, and the gas valve is completely open. If you smell gas or detect a leak, evacuate and call your utility provider immediately.

Step 7: Call For Professional Help If Necessary

After following these steps, if your furnace still won’t produce heat, contact a licensed HVAC technician. Persistent problems could indicate deeper issues—such as damage to pressure switches, frozen condensate lines, or electrical faults.

Why Do Furnaces Lock Down After Exhaust Blockage?

Modern gas furnaces use an array of safety sensors designed to prevent dangerous gases from entering your home. When any part of this system senses abnormal airflow or exhaust, a hard shutdown (lockout) occurs. This is why:

• Safety Lockouts Save Lives: Carbon monoxide is odorless and lethal. Automatic shutdown prevents poisoning.
• Sensors need to confirm normal operation before allowing heat to resume.
• Manual resets ensure a homeowner has inspected and corrected the blockage.

Furnace Exhaust Pipe: Placement, Protection, And Snow Risks

Outdoor furnace exhaust and intake vents are usually placed near ground level for convenience, but this also makes them vulnerable to snow accumulation. Here’s what you should know for better prevention:

• Vents must be at least 12 inches above expected snow levels.
• Landscape features or roof overhangs can create deeper drifts around the vents.
• Plastic or PVC vent pipes are common in high-efficiency furnaces—but these can temper easily and be damaged when frozen.
• Always mark vent locations with a tall, visible stake or pole before winter sets in.

Long-Term Prevention Of Furnace Vent Blockages

Preventing your furnace exhaust from being buried in snow reduces the risk of winter furnace shutdown. Consider these best practices for prevention:

• Clear snow around vents after every major storm—even if the furnace appears to be working.
• Install vent hoods or covers (designed for your model) to direct exhaust above snow level and away from drifting.
• Trim back shrubs or landscaping that could hold snow near vent openings.
• Keep roof drainage directed away from vent pipes to avoid forming ice dams or drifts.
• Check vent pipes for sagging or separation where snow can enter.

Troubleshooting Guide: Why Is The Furnace Still Not Working?

Symptom	Potential Cause	Suggested Solution
No Power	Tripped Breaker or Fuse	Reset Circuit Breaker; Replace Blown Fuses
No Flame Ignition	Wet or Dirty Flame Sensor	Dry & Clean Flame Sensor (Professional Recommended)
Furnace Cycles On and Off	Pressure Switch Issues	Check Switch & Vent Pipe For Moisture; Call Technician
Thermostat Not Responding	Dead Batteries, Wiring Fault	Replace Batteries; Inspect Wiring
Error Code Displayed	Safety Lockout, Internal Fault	Reference Manual; Reset; Call Technician If Issue Persists

Can Resetting The Furnace Fix The Problem?

In many situations, a simple reset is enough to bring the furnace back online after the vent is cleared. However, repeated resets or persistent lockouts indicate unresolved issues. Never force repeated resets: it could damage sensitive controls or bypass important safety mechanisms.

Temperature Swings And Homes With Smart Thermostats

Sudden furnace shutdown in homes with smart thermostats can lead to delayed restarts—even after the vent is cleared. Some systems require digital confirmation or error clearing before heat resumes. Try restarting both your smart thermostat and the furnace for a synchronized reset.

Can DIY Solutions Help When Heat Doesn’t Return?

Cautious homeowners can perform basic checks, such as vent clearing, thermostat resetting, or power cycling. However, if you ever suspect gas leaks, electrical faults, or persistent moisture in vent pipes, always call a licensed professional. Some repairs demand specialized tools and training.

The Importance Of Regular Furnace Maintenance

Yearly professional furnace inspections can help prevent winter emergencies. Technicians will check venting, sensors, and condensate drainage to ensure your system is ready for harsh conditions. Maintaining a clean, debris-free area around your furnace—inside and outside—further reduces the risk of shutdowns.

Common Questions About Furnaces And Snow Blockages

Is It Safe To Use A Hair Dryer Or Heat Gun To Melt Ice In The Vent?

Using a hair dryer may seem effective but can crack plastic vent pipes or create moisture inside sensitive mechanical areas. Avoid using heat sources directly on furnace vents.

What Should I Do If My Furnace Smells Like Gas After Clearing The Vent?

Gas odors require immediate action: evacuate your home and call your local utility emergency line. Do not attempt to relight or reset your furnace until cleared by a professional.

Can Wet Sensors Dry Out On Their Own?

In some cases, furnace sensors will naturally dry and the system may reset after several hours. However, if problems persist, have a technician check for permanent moisture or corrosion damage.

When To Replace Exhaust Components After Snow Blockages?

If snow or ice repeatedly buries your vent pipes, consider upgrading to enhanced vent hoods, rerouting exhausts higher up exterior walls, or adding weather shields. Persistent issues can stress older PVC piping and pressure switches, increasing the risk of future failures. Consult an HVAC pro for upgrades.

Staying Safe: Preventing Carbon Monoxide Incidents

Always have at least one working carbon monoxide detector in your home, especially near sleeping areas. Detectors are critical any time your furnace operates after an incident involving blocked exhaust vents. Test alarms regularly and replace batteries each season.

Key Takeaways For Responding To Furnace Exhaust Blockages

• Always clear snow away from all exterior furnace vents immediately after storms.
• Perform a full reset on your furnace and thermostat to clear any lockout state.
• Check for error codes and refer to your furnace manual for codes or flashing lights.
• If in doubt or problems continue, call a licensed HVAC technician for a full inspection.

Useful Resources For Homeowners

• ENERGY STAR: Guide to Furnace Maintenance and Safety
• US Consumer Product Safety Commission: Carbon Monoxide Information
• InterNACHI: Proper Venting of Gas Appliances