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What’s the Difference Between Atmospheric Vent and Power Vent?

3 min read • June 9th, 2016

Heil Plumbing

Most people don’t know a lot about water heaters. You may simply know that when they work, your shower is hot, and when they don’t, they let you know quickly with a blast of cold water.

Two of the most common type of water heaters are atmospheric vent water heaters and power vent water heaters. While atmospheric vent water heaters are simple and don’t require electric power or moving parts, power vent water heaters use a fan to push the excess gases through the venting pipes and outside. Continue reading to learn more.

Types of Venting

There are several venting styles, but the two most popular are atmospheric and power venting. Let’s explore how each of these works.

Atmospheric Venting

If you look at your current water heater and see a metal pipe rising from the top, you most likely have one of these. The atmospheric venting heater is the oldest type available. With this system, fuel is heated and it warms the water. The pressure of the combustion pushes excess gas upwards and out of your chimney. Enough fuel must remain in the tank once the water is heated to allow enough pressure to push these gases upwards and out.

The biggest advantage of this kind of venting is that no electricity is needed, so the water will still heat even if the power goes out. This is a simple structure that is often found in older houses; it’s easy to replace and is often the least expensive choice. There are, however, a couple of important disadvantages.

Enough heat has to remain in the atmospheric venting tank to effectively make the gases rise. This means that some of the fuel being burned does not go to heating water but instead rises upward and out the chimney with the gases. This is a waste of energy and money. Even worse, if something should go wrong and the gases do not rise as they should, the buildup of gases can leak into the living area of your home. This can make you sick or cause an explosion.

Power Venting

These water heaters use a fan to push the excess gases through the venting pipes and outside. Because they use a fan, the gases are not as hot as those in older tanks, and a lighter, plastic-type of pipe can be installed.

Power venting heaters are more energy-efficient because all the fuel that is used goes to heating the water. The use of the fan allows for a more consistent pressure to push the dangerous gases out of your home, so there is less chance of something going wrong to cause an explosion.

On the negative side, this type of venting is more difficult to install so it costs a bit more initially. It is also necessary to have electrical power to operate the fan, which means that if you lose power, you also lose hot water. Finally, this type of system is a bit noisier because the sound of the fan running is added to the equation.

Why You Need a Vent

Gas and propane water heaters accumulate flue gases, mainly made up of water vapor and carbon dioxide. The vapor is acidic and needs to be released outside in order to relieve combustion pressure that can cause a water heater to explode. The location of the heater is what often determines the best venting method, but you also need to make sure the venting method can handle the power of the heater. If the water heater isn’t vented properly, your home, health, and even life can be at stake. This is why it is necessary to have a skilled technician install any water heater. Venting systems include the vent pipe, flue baffle, and draft hood, all of which needs inspected and cleaned once a year.

The Heil Difference

We’re dedicated to offering the highest quality residential and commercial plumbing services for every customer. Our plumbers are available to respond to your call 24 hours a day, seven days a week. Our residential and commercial plumbers in Columbia and Ellicott City cover every need, from simple fixture repairs to complex drain and sewer problems.

While we are based in Jessup, Maryland, our plumbing contractors also service Catonsville, Columbia, Ellicott City, Odenton, Clarksville, Elkridge, Fulton, Laurel, and Severn.


Eddie Heil

8177 Mission Rd Jessup, MD, 20794, United States

(410) 799-7727

Schedule Service


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