Last Revised: 2/3/26
If your yard is covered in snow, then it’s safe to assume your heating system needs to be working at its best. Yet it’s times right after a snowstorm that many homeowners run into performance issues with their furnace or heat pump.
If your house feels cold even though you’ve double-checked that your thermostat is set correctly, it’s not time to panic; it’s time to take action.
The common culprit? The snow itself. Accumulated snowfall can bury critical components that your heating system needs to function. Those white PVC pipes on the side of your house, your heat pump’s outdoor unit, and other HVAC terminations around your home’s exterior could be completely blocked after heavy snowfall. And when they’re blocked, it’s no surprise that your furnace or heat pump is running into issues.
The good news is that most of these problems are a quick fix once you know what to look for. Here’s what you need to know about keeping your HVAC system clear of snow and why those five minutes of maintenance could be the difference between a comfortable and cold house.
Let’s start with the most important part: how to keep your heating system running all winter.
How to Keep Your HVAC System Clear and Running All Winter
Preventing most snow-related HVAC problems is surprisingly simple and doesn’t require any special tools or technical knowledge. Here’s your winter maintenance checklist:
HVAC Maintenance After Every Significant Snowfall
Checking your HVAC components should be a part of your snow removal routine, just like shoveling the driveway or clearing the walkways.
For high-efficiency furnace pipes: Check your exhaust pipes (the PVC ones protruding from your home) after every significant snowfall. If you can see snow piled up around or covering the PVC pipes sticking out of your home’s exterior, clear it away immediately with a shovel or broom.
Make sure to clear at least two to three feet around both pipes to prevent snow from blowing back in, and keep the openings themselves clear of snow too. If you see any snow or ice blocking the openings, gently remove it carefully as to not damage the pipes or any protective screening.
For heat pump outdoor units: Clear snow from around the entire outdoor unit, creating a clearance of at least two feet on all sides to ensure proper airflow. Gently brush or sweep snow off the top of the unit and the fins. Do so carefully (don’t use a shovel or other sharp objects), and brush in the direction of the fins.
For other exterior terminations: Walk around your home’s exterior and check that all other vents are clear of snow. This can include dryer vents, water heater vents, bathroom exhaust vents, and any other venting terminations. A smart approach to solving this problem is to take pictures ahead of any snow so that you’ll know where you should be clearing snow away from.
Signs Your Heating System Intake and Exhaust Pipes May Be Blocked
Even if you’re being proactive about clearing snow, here are the warning signs that indicate your equipment might be blocked and needs some immediate attention.
Furnace warning signs:
- Your furnace cycles on and off repeatedly without truly heating your house.
- You see error codes flashing on your furnace display.
- The furnace won’t start at all, or starts and immediately shuts down.
- You notice excessive ice buildup on the exhaust pipe.
- You can’t see any exhaust vapor when the furnace should be running (there’s usually a small plume of water vapor visible on cold days).
Heat pump warning signs:
- The outdoor unit is running constantly, but your home isn’t warming up.
- You hear unusual sounds like grinding, squealing, or labored fan operation.
- The unit goes into defrost mode very frequently (every 30-60 minutes or more).
- The outdoor unit is completely covered in ice.
- The heat pump shuts off, and your backup heat (emergency heat) keeps running.
- Your energy bills spike suddenly during cold weather.
Other warning signs of snow blocking exhaust pipes:
- Your clothes dryer takes much longer than normal to dry clothes, or your clothes are still damp after a full cycle.
- You smell unusual odors that could indicate poor venting.
- You notice excess moisture, condensation, or mold in bathrooms or other areas with exhaust fans.
If you notice any of these signs during or after snowfall, check out all your exterior HVAC components. Clear any visible snow or ice, then let your heating system run again. If the issues persist after clearing snow and ice, there may be a more serious problem that requires professional service. Ignoring lingering issues with your heating system could lead to carbon monoxide risks, fire hazards, equipment damage, efficiency losses, or electrical hazards.
Now that we’ve covered what you need to be aware of when it comes to your exhaust and intake pipes (as well as your heat pump’s outdoor unit) during a snowstorm, let’s take a closer look at why it’s so important in the first place.
Understanding Your High-Efficiency Furnace Intake and Exhaust Pipes
If your furnace is 90% efficient or higher (also called a condensing furnace), it works differently from older, traditional furnaces. These modern systems are incredibly efficient at extracting heat from combustion. In fact, they extract enough heat that the exhaust gases chill to the point of condensing into water (hence, a condensing furnace).
Instead of using traditional metal chimney venting pipes, condensing furnaces use PVC pipes that are run horizontally through an exterior wall of your home. This horizontal venting further increases efficiency as it expels exhaust out of your home quickly through a shorter, more direct path, often supported by an internal induction blower motor.
These PVC pipes usually stick out of your home’s exterior somewhere between 4 to 12 inches above ground level. One is the intake pipe that pulls fresh air from outside into your heating system, and the other is the exhaust pipe. For your heating system to function, both of these pipes must be clear.
Yet when they’re blocked, a lot of people forget that the issue with their heating system could really be as simple as making sure they’re clear.
What About Heat Pumps & Other Vented Appliances?
Heat pumps still utilize their outdoor unit during the winter months, and heavy snowfall or ice can restrict the fins from spinning. Those fins are responsible for transferring heat between the outdoor air and your home’s heating system, so when they’re blocked or buried, your heat pump simply can’t do its job efficiently.
Likewise, other wall-vented appliances like drying machines and gas-powered water heaters may be susceptible to the impedance of their exhaust pipes by snow.
Depending on what’s blocked, the result is some combination of: no heat, safety hazards, equipment damage, reduced efficiency, and potentially very expensive emergency service calls.
What Happens When Snow Blocks Your HVAC Components?
Let’s break down what happens when different parts of your HVAC system get blocked by snow.
For high-efficiency furnace pipes: If the intake pipe gets blocked, your furnace is starved for the oxygen it needs for combustion. Modern furnaces have safety sensors that will detect this and shut the system down to prevent dangerous conditions. You might notice the furnace trying to start but then shutting off repeatedly. This is the safety system doing its job, but it means you’re not getting any heat.
If the exhaust pipe gets blocked, the combustion gases have nowhere to go. Again, safety sensors will kick in and shut down the furnace. But there’s also the risk of carbon monoxide backing up into your home, which is exactly why those safety sensors exist.
Pro Tip: Never try to override or bypass safety features; they’re there for a good reason.
For heat pumps: When the outdoor unit gets buried in snow, or the fins become blocked with ice, airflow is restricted. Many heat pumps have a defrost mode. However, when in this mode, the unit has to work much harder to move heat, which reduces efficiency and increases your energy bills.
If you have a heat pump and find yourself with no heating output due to snow, ice, or frigid temps, talk to a professional about both a short-term and long-term solution. Help with your heating system is only a call away.
For other vents and terminations: Blocked dryer vents create fire hazards and prevent proper drying. Blocked water heater exhaust vents can cause the same carbon monoxide risks as blocked furnace pipes. Blocked ventilation system exhausts can also lead to moisture accumulation, mold growth, and poor indoor air quality.
Why Modern HVAC Systems Are More Vulnerable to Snow
Here’s what makes today’s high-efficiency HVAC equipment particularly susceptible to winter weather (compared to what your parents might have had).
Low installation height: High-efficiency furnace pipes are usually installed about 4 to 12 inches above ground level, right around the level snow can reach during a heavy storm. Heat pump outdoor units sit directly on the ground or on a small pad just a few inches high.
Traditional furnaces vented through chimneys well above the roofline, so this is a relatively new risk homeowners are facing.
Cooler exhaust temperatures: Since high-efficiency furnaces extract so much heat, the moisture in exhaust gases can condense and freeze right at the pipe opening when temperatures drop below freezing. Ice buildup can restrict airflow or completely block the opening.
Active intake requirements: The intake pipe will turn on automatically, regardless of the snow situation. And if there is snow, it can be pulled into the pipe, melt, and then refreeze, blocking or partially blocking the oxygen intake for the system.
Heat pumps operate in winter: Unlike air conditioners that only run when it’s hot out, heat pumps operate year-round, including during the worst winter storms. Solving winter-related problems with outdoor HVAC units is new terrain, and cold-climate heat pumps do an excellent job operating at sub-freezing temperatures.
When to Call a Professional vs. Handling It Yourself
You can and should clear snow away from your HVAC equipment yourself as part of routine winter maintenance. However, there are situations where you should call an HVAC professional rather than trying to fix the problem yourself.
Call a professional if:
- Clearing the snow doesn’t restore heat, and your system still won’t run properly.
- You see signs of carbon monoxide exposure, or your CO detector goes off.
- There’s significant ice buildup inside the pipes or on heat pump coils that you can’t safely clear.
- You notice damaged heat pump fins, bent fan blades, or other equipment damage.
- This is a recurring problem, winter after winter.
- You notice any damage to pipes or vents: cracks, separation at joints, missing screens or caps.
- Your heat pump is completely encased in ice and won’t defrost.
- You’re physically unable to safely clear snow from your equipment.
Making This Part of Your Winter Routine
The best approach to avoiding problems with snow-blocked HVAC equipment is to make checking all intake and exhaust pipes a part of your regular winter routine, especially during periods of active snowfall.
Here’s your quick checklist:
- Clear furnace intake and exhaust pipes
- Clear around and on top of heat pump outdoor unit
- Check dryer vent
- Check any other visible exterior terminations
It’s a 5-minute job that can save you from waking up to a cold house, prevent fire hazards, and avoid paying for expensive emergency service.
And for winterizing your plumbing system, here’s a quick checklist of what you need to be aware of.
Don’t Wait Until You’re Sitting in a Cold House
Now you know what to look for and what to do. You’re prepared to handle whatever winter weather comes your way.
Those white PVC pipes, your heat pump outdoor unit, and those various venting terminations around your home might not seem important, that is until they’re blocked and you’re left without heat on one of the coldest nights of the year.
Want to make sure your HVAC system is properly installed and ready for winter weather? Contact Mattioni at (610) 400-8510 to schedule a comprehensive heating system inspection. Or book your appointment online. With over 75 years of trusted service, our expert technicians can assess your furnace, heat pump, and all exterior terminations to make sure everything is properly positioned and protected.
Already dealing with heating equipment that won’t stay running or suspect snow and ice might be causing problems? Don’t wait. Call today for same-day emergency service. We’ll diagnose the problem, get your heat back on fast, and help you prevent it from happening again.
