Tankless Water Heater Venting is not easy but the most wise decision to reduce utility expenses as well as lower energy consumption. Unlike a tank, a tankless water heater requires special venting. It blows hot exhaust gas outside, where it dissipates. However, the gas tankless water heater venting offers far more versatile options.

Regardless of everything, here we have the best ways for tankless water heater venting. It will make the installation process easy and energy-efficient without paying high expenses. The more attractive and easy-to-fit design ensures space-saving. So lets’ get started on which things you need for tankless water heater venting.

8 Things You Need to Know for Tankless Water Heater Venting

Venting Tankless Water Heater Guide


Air Combustion: Do you know that the propane tankless water heaters don’t come with indoor air for combustion? As far as the venting tankless water heaters, there are two ways. That is:

Power Vent: This type of venting uses indoor air for combustion. In this way, they simply vent the exhaust outside. Unlike direct vents, they have only an exhaust vent. However, they need certain considerations. For instance, you have to place them in a large room so that they can get enough air for gas combustion. 

Direct Vent: while this type of unit vents pulls in the air from the outside. They have two vents for intake and exhaust. They use outdoor air, and you have to keep them in smaller places, unlike power vents. 


Even for direct vents, tankless water heaters don’t always require two ventilation pipes.  Since we told you that direct vents need two pipes separately for both intake and exhaust. However, there are lots of brands that allow concentric venting tankless water heaters.  

As far as the concentric vents are concerned, they provide lots of benefits. Such as, the plumber has to make one penetration in the wall or ceiling. Not only that, the concentric vents are cool to touch because they keep the warm exhaust air inside, unlike exhaust vent pipes.

What’s more? When it comes to the concentric vents are large in size when it comes to diameter. Also, there is no need to get extra clearance through the wall. They provide lots of safety. Such as, if the inner exhaust vent gets any leakage issue, the exhaust air will stay connected within the intake pipe. 


There is no need for a tankless water heater venting through the roof. While the propane water heaters vent through the roof for storage tank using galvanized steel B-vents. It is because they work via the natural draft. This system offers risen the hot air. However, the tankless water heater can terminate on a sidewall. Here is a reason why because they blow exhaust from combustion horizontally. In addition to this, it is good for professionals to replace the electric tanks that don’t need venting.

Hence it would be expensive as well as hard to go through the roof for venting. While if you are venting with the sidewall, then it means you have a lot of flexibility in where you put the unit.


When it goes to the outdoor tankless water heaters, they don’t need venting. Not only that, if you are planning to install tankless water heating, then wait for the warmest climate to makes the installation process easier. 

You should also keep in mind that tankless units are manufactured to withstand freezing temperatures due to the self-warming capabilities. This will prevent freezing as well as cracking. 

On the other hand, a tank water heaters can freeze in a cold climate where electrical outages occur. That’s why it is better to install indoor. 


If you are using a condensing tankless water heater, then there is no requirement for metal venting. It is because when it comes to them, they transfer water only about 80% of the heat they generate. At the same time, the remaining heat creates a hot exhaust gas that needed metal venting. It is the same as thick aluminum ad stainless steel. 

More than that, the condensing units are 95% efficient. It is because of the exhaust gas temperature, which is lower.  Being said that, it needs affordable plastic for venting such as PVC or polypropylene. However, the price depends on the efficiency of the unit. There are lots of brands that say that the overall installation cost of the high-efficiency unit is equal to or lower than its mid-efficiency unit.


Not everyone has to be a box stuck to a wall for the placement of a tankless water heater. Unlike new construction applications, you need to keep the tankless water heater inside the wall. You can fit th conventional stud up to 14 inches wide for the non-condensing units. More than this range need more creative farming.


When it comes to large residential applications or commercial ones, they use multiple tankless water heaters. There is no need to vent penetration per unit. However, usually, manufacturers engineered a common venting system that uses a manifold to share the same exhaust. Apart from that, lots of buildings needed practical yet aesthetic units, and they want to avoid extra penetrations.


Make sure the venting is not looking ugly. You have to designed aesthetically that looks pleasing. Such as, lots of manufacturers want a tankless water heater, but they end this option. The reason is that they don’t want to get a hole in the wall. If you are one of them, then you don’t need to worry. There are lots of attractive covers available that look pretty.


Does A Tankless Water Heater Need Venting?

Tankless water heaters need venting like tank water heaters. Unlike tank design, they require special venting to blow hot exhaust gas outside when it comes dissipates. However, they offer far more versatile venting options, so your life stays easy.

Can I Use The Existing Vent For A Tankless Water Heater?

No, you can’t use existing vent piping with any other appliance. They don’t use a masonry chimney flue for venting since they need a special stainless steel pipe. With standard galvanized Vent from your existing tank will make rust quickly away only when your tankless water heater is vented through it.

Can A Water Heater Be Vented Out A Sidewall?

The natural gas tankless water heater must be vented to the outside wall to eliminate the byproducts of combustion. The vents should be outside of the wall to bring combustion air to the gas burner to provide better performance.

Conclusion – The Bottom Line:

All in all, if you want to know about tankless water heater venting, then we have provided you enough details that would be helpful for you. It ensures easy installation, so you will get your job done perfectly for venting. Besides that, we would also appreciate your suggestions and experience for venting. Let us know that in the below-commenting section. Thank you for visiting us!