How to Vent a Tankless Water Heater: Step-by-Step Guide.

To vent a tankless water heater, connect the exhaust pipe to an exterior vent pipe and ensure proper installation with upward sloping. Proper venting of a tankless water heater is crucial for efficient and safe operation.

Without proper ventilation, combustion gases may build up and produce hazards that could affect the health of the occupants and cause damage to the unit. Venting allows these gases to exit the home, preventing any potential mishaps. Moreover, a poorly vented system can lead to a drop in the water heater’s efficiency and increase energy bills.

Therefore, it is essential to follow the manufacturer’s guidelines and local codes when venting a tankless water heater, ensuring that it is safe, efficient, and up to code. In this article, we provide you with a step-by-step guide on how to vent your tankless water heater correctly.

How to Vent a Tankless Water Heater: Step-by-Step Guide.


Types Of Venting

When it comes to tankless water heaters, venting is a crucial factor that guarantees the safety of your home and the longevity of the appliance. Venting refers to the process of removing exhaust gases from the water heater. There are three types of venting: direct vent, power vent, and condensing.

In this section, we’ll take a look at each type’s characteristics.

Direct Vent

Direct venting requires two pipes. One draws fresh air from the outside to the heater, while the other excretes exhaust gases back outside. Direct venting is ideal for those who want a more energy-efficient system. It is also quieter than the other types of venting.

Here are some advantages of direct venting:

  • Energy-efficient
  • Quiet operation
  • Suitable for small spaces
  • Cost-effective

Power Vent

Power venting is a popular option for tankless water heaters because it uses a fan to blow exhaust gases out of the house. This method allows homeowners to vent the heater using pvc pipes instead of metal. The fan can be powered by either electricity or air pressure.

Here are some advantages of power venting:

  • No need for a chimney
  • Compatible with pvc pipes
  • Can vent horizontally
  • Quiet operation


Condensing venting is the most efficient method. It utilizes two heat exchangers, allowing it to use more heat from exhaust gases to heat water. Because of this, the gases that are exhausted are much cooler than those from other types of venting.

Due to its efficiency, condensing venting is often the most expensive option.

Here are some advantages of condensing venting:

  • Energy-efficient
  • Environmentally friendly
  • Reduced operating cost
  • More durable

Choosing the right type of venting for your tankless water heater is crucial. Proper venting guarantees safe and efficient operation and increases the appliance’s lifespan. Choose the type of venting that best suits your needs, budget, and space to enjoy endless hot water without any worry.

Venting Materials

Tankless water heaters are an excellent investment for homeowners, providing a constant supply of hot water while saving energy and space. However, these systems require proper ventilation to ensure efficiency and safety. Here’s everything you need to know about venting materials for your tankless water heater.

Pvc Pipes

Pvc pipes are a popular choice for venting tankless water heaters due to their affordability and ease of installation. Here are some key points to keep in mind regarding pvc pipes.

  • Pvc pipes are lightweight and easy to handle, making them ideal for diy projects.
  • These pipes are durable and long-lasting, providing an excellent lifespan for your tankless water heater.
  • Pvc pipes have a high resistance to corrosion, rust, and chemicals, ensuring that your venting system will function correctly for years.
  • When using pvc pipes, it’s essential to use high-temperature cement to join the pipes and fittings to prevent leakage.

Metal Venting

Metal venting is another popular choice for tankless water heaters, offering strength and durability. Here’s what you need to know about metal venting.

  • Metal venting is made of aluminum or stainless steel, offering high resistance to corrosion and rust.
  • These vents can have either a single or double-wall construction, where the double-wall option provides additional insulation, reducing heat loss and condensation.
  • Metal venting requires specialized tools for cutting and installation, making it a less viable diy option.
  • Some codes and regulations require specific types of metal venting for tankless water heaters, so it’s essential to research thoroughly before purchasing.

Flexible Venting

Flexible venting is an excellent option for those who need to navigate tight spaces or require a versatile solution. Here are some key things to consider with flexible venting.

  • Flexible venting is lightweight and easy to install, providing a convenient solution for tricky installation scenarios.
  • These vents are made of stainless steel with a corrugated design, allowing flexibility and easy maneuvering around bends and corners.
  • Flexible venting is typically not used for longer runs or when venting vertically, making it a more niche option.
  • Ensure that you purchase flexible venting designed explicitly for tankless water heaters, as general-purpose flexible venting may not meet code requirements.

Careful consideration of your ventilation options is crucial to ensure that your tankless water heater functions efficiently and safely. Whether you opt for pvc pipes, metal venting, or flexible venting, ensure that you follow all code requirements and manufacturer guidelines to keep your heating system in top condition.

Venting Installation

Tankless water heaters have been gaining popularity over the years due to their many benefits. Among them is the fact that they take up less space than conventional heaters and heat water on demand. Venting a tankless water heater may sound complicated, but with the right guidance and tools, it can be a straightforward process.

We will go through the steps you should take to successfully vent your tankless water heater.

Planning The Installation

Before beginning the installation process, it is essential to prepare adequately. Here are the key considerations:

  • Get the right permits: Check with your local authority to confirm if there are any regulations you need to adhere to before starting the installation.
  • Select the right location for the heater: The installer should choose a good location that provides ample ventilation and is suitable for the heater’s size.
  • Acquire the necessary equipment: The installer should get the right equipment or tools necessary for venting. The tools should be in good condition, and the right safety gear should be worn during installation.

Step-By-Step Installation Process

Once everything is set, you can proceed with the installation process. Here is a step-by-step guide:

  • Shut off the power supply: Turn off the heater’s power supply and the gas supply.
  • Prepare the vent pipe: The installer should attach a vent pipe to the heater’s flue outlet. Ensure that the pipe is the right size, has no debris or obstructions, and that it’s pitched correctly.
  • Install the vent pipes: Depending on the type of tankless water heater and your local regulations, you may need to install either a single vent pipe or a dual vent pipe system.
  • Secure the vent pipe: After installation, the vent pipe should be attached securely using fasteners, screws, or clamps. The installer should also inspect the joints and connections for leaks.
  • Test the venting: Switch on the heater and inspect for any leaks or improper venting. If there are issues, switch off the heater and call a professional to rectify the problem.
  • Final checks: The installer should conduct a final inspection to ensure that everything is in order and that the heater is venting correctly.

Venting a tankless water heater is not rocket science. With the right guidance and equipment at hand, anyone can install a vent pipe for their tankless water heater. Ensure that you follow all the right procedures and get any necessary permits before starting the installation.

Troubleshooting And Maintenance

Tankless water heaters have become increasingly popular due to their efficiency and space-saving benefits. Proper venting of tankless water heaters is crucial for safety and optimal performance. We will look at troubleshooting common venting problems and regular maintenance tips for tankless water heaters.

Common Venting Problems

Even with proper installation, there are a few common venting problems that you may encounter while using a tankless water heater. These include:

  • Vent blockage due to debris or buildup
  • Carbon monoxide leakage
  • Incorrect vent sizing

How To Troubleshoot

If you experience any venting problems with your tankless water heater, here are a few troubleshooting tips that you can try:

  • Check for any visible vent blockage and remove it
  • Make sure that the venting system is correctly installed
  • Look for any signs of carbon monoxide leakage, such as a yellow flame or soot buildup, and repair immediately
  • Inspect the vent size and make sure that it’s the correct size for the unit

Regular Maintenance

Regular maintenance is key to prolonging the life of your tankless water heater and to keep it functioning efficiently. Here are a few maintenance tips you can follow:

  • Clean the air intake filter every six months
  • Check the venting system for any signs of damage or blockage
  • Inspect the heater for any leaks
  • Flush the unit once a year to remove any mineral buildup

Troubleshooting and maintenance of a tankless water heater’s venting system is essential for safety and optimal performance. By following these tips, you can ensure that your unit functions efficiently and lasts for years to come. Remember to schedule regular maintenance checks to identify and resolve any potential issues before they become major problems.

Frequently Asked Questions On How To Vent A Tankless Water Heater

How Do You Vent A Tankless Water Heater?

To properly vent a tankless water heater, you need to install a vent pipe and terminate it outside. The type of venting system depends on the model of the water heater, and it’s important to follow the manufacturer’s instructions for installation.

Why Is Venting Important For A Tankless Water Heater?

Venting is important for a tankless water heater to prevent the buildup of harmful gases, such as carbon monoxide. Proper venting ensures the safe and efficient operation of the water heater, and helps to extend its lifespan.

What Are The Different Venting Options For A Tankless Water Heater?

There are two main venting options for tankless water heaters: direct venting and power venting. Direct venting uses a sealed vent system that draws in outside air for combustion, while power venting uses a fan to force exhaust gases outside.

Can You Vent A Tankless Water Heater Through A Roof?

Yes, you can vent a tankless water heater through a roof using a vertical ventillation system. However, the vent pipe must terminate at least 1 foot above the roof line to prevent the gases from recirculating back into the home.

How Often Should A Tankless Water Heater Be Inspected?

It’s recommended to have a professional inspect your tankless water heater annually, including the venting system. This ensures that your water heater operates safely and efficiently, and can help prevent costly repairs and replacements down the line.


After reading this guide, venting your tankless water heater should now feel like a manageable task that can be done with the right tools and a bit of patience. Remember to take safety precautions and to follow the manufacturer’s instructions carefully to avoid any accidents or damage to your system.

Regular maintenance of your tankless water heater will ensure its longevity and optimal performance, and venting is a crucial part of maintaining its efficiency. Don’t hesitate to seek professional help if you’re unsure about anything or feel like you need assistance.

Keeping your tankless water heater properly vented will not only increase its efficiency but also keep your home and family safe from the dangers of carbon monoxide poisoning. So take the time to vent your tankless water heater regularly and enjoy endless hot water and peace of mind.