It’s one of the worst winter feelings. You wake up to a cold house after a big Milwaukee snowstorm, and the furnace won’t kick on. Your first thought is a costly repair, but the answer might be much simpler.
High-efficiency furnaces depend on white PVC pipes to bring in fresh air and safely push out exhaust. During our tough Wisconsin winters, snow and ice can easily block these pipes, causing your furnace to shut down as a safety measure.
Keeping these vents clear is an easy and essential part of your home’s winter maintenance. As a fourth-generation family business, Uttke Heating & Cooling is here to help our Milwaukee neighbors stay safe and warm all season long with a few simple instructions.
What Are Furnace Intake and Exhaust Pipes?
Before you can check your furnace vents, you first need to know what you’re looking for and why they matter. A high-efficiency furnace operates like it’s breathing—it needs a clear airway to work correctly.
Your Furnace’s Lungs
The intake pipe is how the furnace draws in fresh cold air from outside to fuel the combustion process. The exhaust pipe is how it pushes out gases, including carbon monoxide, safely away from your home. You’ll almost always see these as two white PVC pipes sticking out from the side of your house, usually near the furnace unit itself.
Why Are They Plastic?
You might ask why these pipes are plastic instead of metal. A high-efficiency furnace pulls so much heat from the combustion that the exhaust it produces is cooler and full of water vapor. This condensation would eat through a metal pipe in no time, but PVC is made to handle it. The whole system is built for safety and performance, but that depends entirely on both pipes having an open path to the outside.
Why a Blocked Pipe is a Common Milwaukee Winter Problem
When you wake up to a cold house after a big snowstorm, it’s easy to assume the worst. More often than not, the problem isn’t that your furnace is broken. It’s because the system has put itself into a self-protection mode.
Your Furnace’s Built-In Safety Switch
Inside your furnace is a smart safety device called a pressure switch. Its one job is to check that the intake and exhaust pipes are clear. If it senses a blockage from heavy snow, drifting winds, or freezing rain, it will prevent the furnace from starting up.
This is a good thing—it’s a safety feature designed to stop harmful gases from building up inside your home.
What to Look (and Listen) For
The most common symptom is a furnace that tries to start, runs for a minute, and then shuts itself off. You might hear a small “whoosh” or “puff” as it tries to ignite before it goes quiet. You may also see a flashing error code on the unit itself.
These are all classic signs of a venting issue. If your heat goes out after a blizzard, always check your furnace pipes first. It could save you a service call.
Step-by-Step: How To Safely Clean Furnace Intake and Exhaust Pipes
Clearing your furnace vents is a simple job you can do in just a few minutes, but it’s important to do it safely. Follow these seven steps to get your furnace breathing again.
Turn Off the Furnace
Before you do anything else, you must shut down the power to your furnace. Look for a switch that often looks like a standard light switch, sometimes with a red cover, located on or near the furnace itself. Turn it to the “Off” position.
Locate the Pipes Outside
Go outside to the area where your furnace is located. You should see two white PVC pipes sticking out from the side of your house. These are your intake and exhaust pipes.
Inspect for Blockages
Look closely at the openings of both pipes. Check for any obvious obstructions like heavy, packed snow, a thick layer of ice, or even leaves and other debris that might have blown in.
Gently Remove Obstructions
If the blockage is just snow, use your hands or a soft brush to gently clear it away. You should not use any sharp tools, shovels, or sticks, as these can easily crack or damage the plastic pipe.
Melt Ice Carefully
If the openings are covered in ice, you can melt it by pouring warm (not boiling) water over the pipe. You can also use a hair dryer on a low setting.
As you clear it, look for a “frost ring” or icicles—this can be a sign of a deeper issue with the pipe’s slope, so it’s a good thing to mention if you end up needing a service call.
Do a Quick Interior Check
Once the openings are clear, shine a flashlight a few inches into the pipe to look for anything further inside, like an animal’s nest.
Gently tap the side of the pipe inside your home—if you hear a rattling sound, it could mean debris has fallen deep inside. In that case, it’s time to call a professional.
Restore Power and Test
After confirming the pipes are clear, go back inside and turn the power switch back on. Your furnace should now start up and run normally within a few minutes.
A quick safety reminder: Never insert any object deep into the pipes or try to take them apart yourself. This can create a serious safety hazard and is a job for a licensed technician.
How To Prevent Future Blockages
Once your furnace is running again, a few simple habits can help stop the same problem from happening after the next big storm. Keeping your furnace vents clear is all about making it part of your regular winter routine.
Keep the Area Clear
Try to maintain an open space of about a metre around your vent terminations. Trim back any shrubs or bushes in the autumn, and make sure snow blowers or ploughs don’t pile snow up against that side of the house.
Make it a Habit
Here in Wisconsin, lake-effect snow can pile up in a hurry. After any big snowfall, make it a habit to take a quick walk around your house. A quick sweep with a broom to clear away any drifts from your furnace pipes is all it takes to prevent a no-heat emergency.
Consider Professional Solutions
You can have protective covers or screens installed over your vents. It is important that these are professionally selected and installed. Never try to create a DIY cover, since restricting airflow in any way can be just as dangerous as a blockage.
The best prevention is to schedule your seasonal furnace maintenance in the fall. This ensures everything is venting properly before the first snowflake falls.
When To Call a Professional
While clearing snow and ice is a safe and easy task for you to handle, some symptoms are clear signals that you have a deeper issue. Your furnace is a complex piece of equipment. Knowing when to call for help is just as important as knowing what you can do yourself.
Here are a few red flags that mean it’s time to pick up the phone.
The Problem Keeps Coming Back
If you clear the pipes and the furnace works for a day or two but then shuts off again, even without a new snowfall, it could be a sign of an intermittent problem. A component like the pressure switch itself might be failing. This requires a professional diagnosis.
You See Water Where it Shouldn’t Be
Look at the PVC pipe joints inside your home. If you see any water stains on the wall, or worse, active dripping, it’s a sign of a bad seal or a clog deep inside the system. You should not ignore this.
You Notice Soot or Black Marks
The exhaust from a high-efficiency furnace should be clean. If you see any black, sooty residue around the exterior exhaust pipe, it’s a major warning sign that the fuel is not burning properly. This is a potentially dangerous situation that needs to be addressed immediately by a professional.
If you experience any of these issues, a licensed HVAC technician from Uttke Heating & Cooling has the tools and training to safely inspect, clean, and resolve the problem.
Keep Your Furnace Running Safely This Winter
Keeping your furnace vents clear is a simple but necessary part of your Milwaukee winter routine. It’s an easy check that can save you the stress of a no-heat emergency and give you the peace of mind that your system is running correctly.
For over 80 years, our family has been dedicated to keeping our neighbors on Milwaukee’s South Side safe and warm. If you’ve cleared your pipes and are still having trouble, or if you’d just like the security that comes with a professional tune-up, give our family a call.
From our home to yours, we’re here to make sure you stay warm all season long. You can schedule your service today.