Vent Ice Formation: Causes and Prevention Tips

Ice formation in furnace vents can hinder the vent’s and, by extension, the furnace’s performance.

You should know why moisture sometimes freezes in the vents to prevent such occurrences.

Below are some causes and prevention measures for such ice formations.

Causes of Vent Ice 

The vent channels should allow spent gases to flow out of the house without restriction.

Anything that blocks the vent openings or pipes can interfere with this operation.

For example, ice can form on and block the vent pipes. Below are the possible causes of such ice issues.

Improper Vent Slope

The vent pipe should slope towards the furnace.

The slope is necessary to allow moisture that condenses within the pipe to flow back to the furnace.

That way, the moisture can flow into the furnace’s condensate pipe and eventually into a floor drain.

An improper pipe slope allows the moisture to stagnate and freeze within the pipe.

Lengthy Vent Pipes

An extremely lengthy vent pipe creates two problems.

First, the spent gases might not have enough pressure to flow and exit the vent pipe.

Second, the condensate might freeze before it reaches the furnace’s drain system.

Too Many Elbows

Vent elbows are necessary, but too many of them can create two major problems.

First, each elbow increases the overall length of the vent pipe.

Second, each elbow also increases the restrictions the spent gases must overcome to exit the vent pipe.

Thus, too many elbows might cause moisture to freeze before it can exit the vent.

Wrong Vent Screen

A vent screen prevents debris and pests, such as bugs, from getting into your house.

However, the wrong vent screen can create problems for the furnace’s exhaust system.

For example, fine mesh screens can trap debris and snow, providing the seeding centers for ice formation.

Vents Too Close to the Ground

Vent pipes too close to the ground create two main problems.

First, snow can accumulate and block the vents, which can cause the moisture to freeze.

Secondly, most restrictions, such as bushes, are near the ground and can clog the vents.

Debris Clogging

Debris from outside the house can also enter and clog the vent channel.

That might happen, for example, if you don’t use a vent screen or if something has damaged the vent screen.

The debris will restrict airflow out of the vents and increase the risk of freezing.

Sagging Vent Pipes

A good vent pipe should have adequate support throughout its length.

Otherwise, the pipe might sag.

The risk of sagging is high if the pipe is lengthy or a relatively weak or thin material.

The sagging will increase unnatural bends in the vent pipe and restrict exhaust flow.

As usual, restricted venting increases the risk of ice formations.


Prevention Tips

Professional HVAC contractors understand the significance of efficient vent systems and design them properly.

Therefore, the first tip is to use a professional contractor to design and install your entire HVAC system.

The second tip is to avoid DIY repairs or installations.

For example, contact a contractor if something damages your vent pipe and you need a replacement.

The contractor will ensure the replacement vent meets the relevant specifications.

Lastly, maintain your HVAC system.

For example, you should ensure the vent openings are always clean.

Otherwise, blockages might encourage ice formation on the openings.

Hopefully, you will use a professional HVAC contractor for all your heating needs and avoid vent or other related problems.

Chrismon Heating & Cooling has trusted heating technicians that can install and maintain your heating system.

We promise to leave you satisfied with our professionalism.

Contact us for quotes on all HVAC services you may need.