How to Vent a Tankless Water Heater – Everything You Should Know

Conventional geysers are becoming more of a history with the advancing age. Users now prefer instant water geysers, where they don’t need to worry about water storage or the availability of warm water. 

Instant geysers are also known as tankless water heaters. As the name states, it does not have any water storage and works directly to warm up the water as needed. Staying idle initially, it fires up as soon as water flows.

Its compact size allows the flexibility to be installed at multiple points around the house. Also, every heating appliance needs ventilation to operate smoothly without heating up dangerously. 

Tankless water heaters also need adequate ventilation. If you look forward to installing one in your home, you must know how to vent a tankless water heater.

An Insight Into Tankless Water Heaters

electric water heater

With advanced technology, things are getting more convenient and accessible. Before heaters or geysers were introduced, people had to rely on wood or burners to warm up their water.

A gas tank water heater or geyser was a great invention to make hot water easily accessible. Further advancements were made to make things better and reduce energy waste. 

Traditional geysers consume a significant amount of energy. It keeps burning until the water stored in the geyser’s tank warms up to the desired temperature. If not used for long, the tank water gets cold, and the burner starts to warm it up again.

To reduce energy waste, tankless water heaters were introduced. This type of water heater does not have a storage tank for water – instead, it works on demand. As soon as water flows in, it’s heated to the desired temperature and passed to the faucet.

Types of Tankless Water Heaters

These tankless units are available in two types: electric and gas-powered. As the name indicates, the idea is straightforward: electric-powered water heaters use electricity to warm the water. 

On the contrary, gas-powered water heaters use natural gas to heat water by mixing it with air to form a combustible mixture. These water heaters are further classified into central and point-of-use (POU) water heaters.

Central Water Heater

Central water heaters are large and can be installed to heat water for the whole house.

This type of water heater might take some time to release hot water from your faucet. Although, it depends on the installation point and the distance from the geyser to the tap. 

Point-of-Use Water Heater

A point-of-use water heater is the most compact and convenient type. You can install it at any point around the house or inside your bathroom.

This water heater is very effective because it doesn’t include extended pipes. This saves time and energy by immediately providing hot water.

Operation of Tankless Water Heaters

The working mechanism of tankless water heaters varies depending on whether they are electric or gas heaters. As discussed above, the electric model utilizes electricity, whereas the gas model uses natural gases for heating. 

Both types use copper heat exchangers with high thermal conductivity. This allows for more effective heating and easier fabrication. 

Tankless water heaters stay idle and wait for the water to flow. Once the flow is detected, they work their way to heat the water instantly, saving us both time and energy.

To add convenience, you should install these geysers at the closest point possible to the bathroom or desired faucet.

How to Vent a Tankless Water Heater

Before installing a tankless water heater in your house, you must ensure it’s adequately vented. The ventilation can allow harmful combustion gases to escape into the outer air.

The gases won’t escape and will stay inside the building if it’s not vented. This could pose a risk to the people living in the building, causing health issues like headaches, nausea, and more. So, it’s vital to ensure that you vent a water heater properly to avoid carbon monoxide poisoning.

It’s important to note that tankless heaters don’t require an exhaust pipe or a dedicated exhaust hood. Usually, when a conventional water heater is installed in a building, it has an exhaust pipe that leads outside the house.

Rinnai extends the opportunity for its customers to hire certified experts through the Find a Rinnai PRO section on its website.

You can ask the expert to assist you with the tankless water heater installation. He will inspect the surroundings of your house for the best possible installation point. That expert will likely look for locations where ventilation is easily achievable.

If you like to fix things yourself, you can read Home Depot’s step-by-step guide for installing an instant geyser. A guide for getting hot water faster in your taps can also come in handy for making your setup more effective.

If you are keen on venting a tankless water heater, there are multiple ways to achieve this, depending on the type of geyser and point of installation.

Indoor Tankless Water Heater

An indoor installation is the first and most used type of tankless water geyser. This is compact and can be installed in multiple spots around the house. 

Most people prefer the indoor water heater for its better accessibility and ease of operation. Installing the water heater nearer to the faucet can provide warm water instantly due to the shorter path of the water pipes.

Like every heating appliance, the indoor water heater also requires adequate ventilation. Combustible gases from the exhaust of the heater could be fatal if they leak inside the house. 

There are two types of vents used for indoor water heaters.

Direct Vent

This vent operates very straightforwardly with two ventilation pipes. The intake vent is for pulling the outer air inside the water heater, and the exhaust vent is for exhausting the harmful air outside. It enables the heater to be installed in tight spaces.

It’s important to note that the direct vents are unsuitable if the heater is installed where the ventilation pipes have to cover a greater horizontal distance to the opening outside. They are effective if installed vertically, releasing gases from a chimney.

Power Vent

Advanced but noisy – efficient but expensive.

The power vent is an advanced ventilation system with a fan to blow out exhaust gas. It allows the water heater to be installed anywhere around the house. So you don’t need to worry about the distance of the exhaust pipe.

You can hook it vertically or horizontally. It may be noisy due to the fan, but it effectively pushes the harmful gases outside.

Outdoor Tankless Water Heater

If you want to eliminate the hassle concerning vent pipes and their adjustments, install a tankless water heater outdoors. You won’t have to worry about the ventilation, as it’s already mounted outside the house.

Outdoor tankless water heaters have advanced a lot over the years and can also be used in icy regions. Its system provides automatic heating to its inner components in below-freezing temperatures.

You should look after your geyser regularly to make it last longer. An article about water heater maintenance can come in handy to understand how you can take care of it.

Recess Boxes

You can install your water heater outdoors, but cover it in a box as if it were installed inside the house, making the most of your space.

The idea of recess boxes is to hide your water heater inside the wall cavity, protecting your heater and making your place look neat.

The recess box makes it convenient to use the tankless geyser – it has a space of its own with adequate ventilation. The ventilation of the recess box may vary according to the installation point.

A power vent is better if you install the recess box indoors. This is because it does not need any specific positioning and will work wherever you place it. 

Also, a direct vent will work if it’s installed outdoors because you don’t need additional power to push the air out. It could work through a natural draft using an intake pipe and exhaust vent pipe within the recess box, reaching vertically to the roof.

Think Outside the Box

It also comes down to your creativity in mounting your water heater. You can think of innovative ways to mount the heater in a spot where you can quickly provide additional venting to make way for warm exhaust air.

An ideal location to mount your water heater is outside your bathroom. You won’t have to worry about exhaustive gas leaking inside your house, and will also get warm water immediately.


Upgrading your water heating system from a conventional geyser to a tankless water heater is smart and saves time and energy.

No matter what type of water heater you choose, ventilation is vital for all units. So to answer your question, “how to vent a tankless water heater?”. There are plenty of ways to do that, from direct to power vent.

The point of installation plays a significant role in the ventilation of exhaust gases. As for outdoor heaters, you don’t have to worry about ventilation.

With years of experience under his belt, Adam decided to put his water heater knowledge to work. By providing high-quality content and expert guides, Adam hopes to help anyone looking for expert water heater advice.