Tankless Water Heater Venting Through Your Roof – Everything You Need to Know

A tankless water heater offers plenty of advantages over a traditional storage tank water heater. For starters, a tankless water heater can space and even reduce the cost of your utility bills and lower your overall energy consumption. While it offers plenty of advantages and unique features, just like traditional water heaters, they must be vented properly.

Water heater venting in roof

In other words, if you choose a tankless option, you will still need to add ventilation, as dissipating all of that hot air and exhaust is incredibly important. If your tankless water heater is not vented correctly, your home could potentially fill with dangerous and destructive fumes.

Fortunately, the design of a tankless water heater allows for a variety of venting options. Whether you want to vent your tankless water heater through your roof or out of the side of your home, the choice is yours. Since venting is so important, we have decided to offer this straightforward guide to everything you need to know about venting a tankless hot water heater!

Can You Vent a Tankless Water Heater Through the Roof?

As mentioned, tankless water heater units can vent through the roof, or through a side wall, which creates more flexibility and options for where you will install the unit. Traditional, gas-powered storage tank water heaters must be vented in a vertical direction, which is why they are almost always vented through the roof of the home.

This is because they operate through a process known as natural draft, or atmospheric venting, which means the hot exhaust air rises naturally and travels through a standard, chimney-style flue.

On the other hand, tankless hot water heaters can use fans to blow the exhaust air vertically, or horizontally, depending on the buyer’s preferences. This is because they use a combustion fan that can actually blow the hot exhaust air in any direction.

So, Can You Vent a Tankless Water Heater Vertically?

Yes, with a tankless water heater, the direction the venting system is installed is completely up to you. If venting in a vertical position works best, you can install the venting directly upwards; however, if you have high ceilings, or you do not want to vent through the ceiling for another reason, you always have the option to vent the water heater horizontally.

Venting horizontally, or direct venting, often means the exhaust has to travel a shorter distance to exit your home, which can be beneficial.

Vent a tankless water heater vertically

Do You Always Need Ventilation for a Tankless Water Heater?

While you will always need ventilation for a gas tankless water heater if it is installed inside of your home, you do not have to vent an outdoor unit, as the exhaust vent is already located outside.

If you are running an electric tankless water heater, you will not need to vent the unit at all, as no fuel is being burned, which means it does not produce emissions or exhaust. With that being said, some people will still vent their electric tankless water heaters if they are looking for a way to reduce the amount of hot air it produces.

Those that live in hot climates may find the heat generated by their tankless hot water heater can make things quite uncomfortable inside the home if there is nowhere for all of that hot air to go.

How High Must Your Water Heater Vent Be?

When it comes to determining the correct height for the venting for your tankless water heater, there are no specific numbers. The truth is, as long as the exhaust and emissions are vented out of your home in a safe way, the venting system will work, regardless of height.

If you live in a multi-story home, venting your tankless water heater through the roof could be difficult and somewhat expensive, which explains why some homeowners will opt for a direct, horizontal venting solution. On the other hand, if you live in a single-story home, venting through the roof might be relatively simple, so it could be a preferable option.

Again, the height is less important than the effectiveness of the vent. The main thing is installing the venting system correctly and making sure that everything is safe and secure.

With that being said, your vent pipe cannot be so long that it impacts its effectiveness. Unless you have also installed a more powerful blower, there is a heightened risk of carbon monoxide dropping back down through the vent and re-entering your home if the length of the exhaust is too excessive.

If you have concerns that your vertical venting system is too long, speak with a professional and have them assess the situation for you. Remember, the purpose of the vent is to simply push that hot and noxious exhaust air out of your home as quickly and effectively as possible.

What Happens if a Tankless Water Heater is not Vented Correctly?

If your tankless water heater is not vented correctly, the results can be rather dangerous. For starters, the exhaust produced by a gas-powered water heater can be extremely acidic and corrosive, which means it can cause significant damage to the interior of your home if it is not properly vented outside.

The exhaust can also flow back into the heat exchanger inside your water heater if it is not vented correctly, which can cause serious damage to the water heater and eventually lead to failure.

As you would expect, the exhaust can also put you and your family at risk of carbon monoxide poisoning if it is not vented properly. This is why it is so important to purchase an appropriate venting kit and make sure it is installed correctly.

If you do not think you will be able to install the venting system correctly, you should seriously consider having it installed by a qualified professional, as it is not something you want to take any risks with.

Tankless water heater with vent pipes

Can You Vent a Tankless Water Heater into the Attic?

Given how noxious and damaging the exhaust released by a tankless water heater can be, it is not possible to vent them into the attic. This is a common question; however, the answer is simply no.

As mentioned, the exhaust gas can be rather corrosive, which means it can eventually cause damage to the support beams and insulation in your attic. Not only is it dangerous to risk breathing that exhaust in, it can even impact the structural integrity of your home if it is not properly vented outside.

Final Words

While venting a tankless water heater may sound somewhat complicated, installing the vent system is actually fairly straightforward.

Just make sure you are doing everything in a secure and safe way and consult with the professionals if you have any questions or you are unsure if you installed the venting system correctly. Whether you vent vertically or horizontally really depends on your own preferences, the type of water heater you purchased, and the space you are working with.

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