How To Vent A Tankless Water Heater

7 Tips For Tankless Water Heater Venting

It is one of the most essential decisions a homeowner can make in order to reduce electricity costs and energy usage. Once a gas tankless water heater has been selected, the most critical choice an installer will make when installing a tankless water heater in a home or building will be how the unit will be vented. Special venting is required for tankless hot water heaters in order to exhaust hot exhaust gas outside, where it may disperse. Gas tankless hot water heaters, as opposed to typical tank-style water heaters, provide far greater flexibility in terms of venting.

Tankless Water Heater Venting Features

A skilled tankless water heater installation will come to your house and assess the situation to determine the best solution. Listed below are seven important considerations to bear in mind when determining where to install your new tankless water heater and how to arrange the venting.

  1. In order to determine the greatest match for your property, a skilled tankless water heater installer will check it. Consider the following seven important considerations when determining where to install your new tankless water heater and how to design the venting.

A skilled tankless water heater installation will come to your house and assess the situation to determine the best match. Consider the following seven important considerations when determining where to install your new tankless water heater and how to design the venting.

8 Facts to Know: Venting Tankless Water Heaters

A skilled tankless water heater installation will assess your property to determine which model is the greatest match. Here are seven important considerations to bear in mind when determining where to install your new tankless water heater and how to design the venting.

Facts about Tankless Water Heater Venting

1. Because gas tankless water heaters do not require combustion, they do not pollute the interior air. Tankless water heaters can be vented in two different ways: through a power vent or through a direct vent. Power-vent devices burn fuel with inside air and expel it to the exterior using a simple ductwork system. Due to the fact that direct-vent units draw in air from the outside, they feature two vents: one for intake and one for exhaust. While power-vent units just require an exhaust vent, they raise additional problems about where they should be installed: they must be installed in a room big enough, or in a space with enough vents or louvers, to ensure that they get enough make-up air for the gas combustion.

  • Two ventilation pipes are not necessarily required for tankless water heaters, especially when using direct-vent systems.
  • Concentric vents, according to Trey Hoffman, worldwide product manager at Rinnai, provide a number of advantages over conventional vents.
  • Concentric vents are cooler to the touch than exhaust vent pipes because they keep the warm exhaust air trapped within rather than outside.
  • Consequently, while concentric vents are bigger in diameter (usually 5 inches versus 3 inches for a single pipe), they do not need any more clearance through a wall.
  • If there is a leak in the inner exhaust vent, the exhaust air will remain confined within the intake pipe and will not be able to enter the residence as a result.
  • There is no need for a tankless water heater to exhaust through the ceiling.
  • This is because they function through natural airflow, allowing the hot exhaust air to climb up and out of the home.

Those who are remodeling or working in the industry who are replacing electric tanks (which do not require venting) with propane tankless units may find this information particularly useful, adds Hoffman.

As a result of the fact that you may exit a side wall, you have a great deal of choice in deciding where to place the unit.

Venting is not required for outdoor tankless water heaters.

Tankless units are built to endure below-zero conditions thanks to their self-warming capabilities, which prevent the water from freezing and breaking during storage.

“Not only do you take up 9 square feet on the floor, but you also pick up that cube that goes from floor to ceiling,” he explains.


Non-condensing tankless water heaters usually transmit only approximately 80% of the heat they create to the water they heat, which is insufficient for most applications.

In contrast, condensing units are generally approximately 95 percent efficient, resulting in exhaust gas temperatures that are lower — around 110 to 120 degrees Fahrenheit.

According to Olsen, the price difference in the venting can even be enough to outweigh the cost of the higher-efficiency unit.


Some tankless water heater manufacturers include recess enclosures that allow the tankless water heater to be installed inside the wall in new construction.

“Your water heater is now flush with the exterior of the home,” Hoffman explains further.

It is not always necessary to have many water heater vents installed in a single location.

Rinnai is developing a common-venting system that will use a manifold to share the same exhaust and intake vents for up to eight tankless units at the same time.


Several manufacturers have created vent alternatives that are both functional and aesthetically beautiful.

More information about tankless water heaters may be found on our website dedicated to propane tankless water heaters.

If you want to learn more about the advantages and characteristics of tankless water heaters, you may visit the Propane Training Academy.

Residential water heaters are now subject to new Federal Standards that take effect in 2015. Propane as a viable energy source for heating oil conversion is being investigated.

Tankless Water Heater Venting – A Complete How-to Guide with Tips (Updated February 2022)

TanklessWaterHeaterExpress is sponsored entirely by its readers. Because I am an Amazon Associate, I receive money when people make eligible purchases. In order for your tankless water heater to function properly in your home or office, it must be vented. The correct maintenance and installation of your water heater can help you get the most out of your water heater’s energy. The correct installation is dependent on a number of things. Some of these considerations include fuel type, local code requirements, climate, and safety concerns, which are particularly relevant in the case of gas-fired units that need combustion.

Components of Tankless Water Heater Venting

When venting a tankless water heater at your residence or place of business, there are several considerations to bear in mind. The following are some of the things you should be aware of while installing your water heater:

  • Stainless steel is used for the vent adaptor and the exhaust

A vent adapter is required to connect a tankless water heater to an exhaust hose that has been installed. Depending on whatever water heater type you choose, you need use either a three-inch or a four-inch adapter for the connection. All emissions from liquid or gas water heaters that are tankless require vent pipes that are constructed of stainless steel and authorized by the Underwriters Laboratories (UL). As a result of the heat generated during the venting procedure, this is the case. PVC pipe, as is common in the industry, is not recommended.

  • Electrical models are preferable since they do not require any type of ventilation to function properly.
  • Before installing an electric tankless water heater, be sure you read the owner’s instructions thoroughly.
  • Electrically driven water heaters are available in a variety of sizes and amp ratings to meet your needs.
  • If the product does not match the electrical phenomena requirements specified in the instruction manual, how are you meant to make the necessary modifications?
  • To ensure that you will be able to utilize an electrically powered water heater in your home, consult with an installation or electrician before moving on to the next phase of shopping for a water heater.

Last updated on February 10, 2022 / Affiliate links included / Images sourced from the Amazon Product Advertising API

Outdoor tankless water heaters are also an excellent alternative if you are unable to properly vent a traditional gas water heater. Consult the owner’s handbook of the outdoor model that piques your interest to determine what kind of clearances are required for an outside installation before proceeding.

How To Vent A Tankless Water Heater?

It is critical to properly vent a tankless water heater in accordance with the manufacturer’s instructions before attempting to install the water heater. This will allow your water heater to run properly and effectively, and most importantly, it will eliminate any possibility of danger and, as a result, the chance of carbon monoxide gas poisoning from occurring. Tankless water heaters can be vented horizontally or vertically, which is referred to as tankless water heater venting via the roof in some circles.

On a downward slope, you’ll need an adapter for your vent, a ninety-degree elbow, and a vent hose made of stainless steel that’s the right length.

A little metal or plastic cap will be used to link the interior portion of your vent with the outside wall before you are finished with your exhaust system!

In contrast, for vertical installation, which entails an upward slope, all that is required is that you include a vertical condensation trap in your components list in addition to the previously specified components.

  • Engineered specifically for the venting of gas appliances
  • Having a solid fit and lock ensures that the installation will go well

Last updated on February 10, 2022 / Affiliate links included / Images sourced from the Amazon Product Advertising API Affiliation links and images from the Amazon Product Advertising API were used in this post. Last updated on February 10, 2022. Tankless Water heaters require combustion air to function properly. It is critical to understand how to provide combustion air to your heater, as well as how to provide the ample combustion air that is necessary. Once placed in an open area, combustion air will only circulate the air within your home, providing no further benefits.

Any gas water heater that is tankless and uses combustion air must have a minimum surrounding area of 10,000 cu.

in order to be considered compliant with this guideline.

Models that need combustion air from the outside are required to have a second hose, which is expected to be inserted into the model.

As a result of this, fresh air will be drawn into the space where your water heater will be installed from the exterior of your home. Check the venting instruction booklet of your Rinnai tankless water heater for further information if you require combustion air for your tankless water heater.

Options For Venting A Tankless Water Heater

The process of venting a tankless water heater may be rather scary, but it is extremely vital to be informed of the many alternatives available. Here are some alternatives that may be of assistance in making your decision: Suitable for both horizontal and vertical venting, this is an excellent choice. It makes use of an electric fan to propel the gases outside of your home or office. It draws oxygen from the surrounding environment, which is required for burning.

  • Indoor Direct Vent Sealed Combustion with Fan Assisted Ventilation
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In addition, it has the capability of being vented both vertically and horizontally. The gas burner receives combustion air from the outside, which is delivered directly to the burner. The heater itself is protected by a tight-fitting cover, and it does not draw any air from the environment in which it is mounted. One concentrical pipe gap is created between the two pipes, which goes from the water heater through the wall or roof of the residence. One of the pipes is for exhaust, while the other is for fresh air intake, and they are connected together.

Warm regions should use this form of ventilation, whereas cold climates should avoid it.

7 Tips For Venting Tankless Water Heaters

Listed below are some important considerations to keep in mind while venting a tankless water heater: 1. Tankless water heaters that are put indoors draw in fresh air from the outside environment. Ventilation for tankless water heaters can be accomplished in two ways: by power venting or through direct venting. Direct-vent units draw in outside air from the home or building, whereas power-vent units just require an exhaust vent and should be located in a bigger area in order to get a sufficient volume of air for burning.

  • The installation of outside-mounted tankless water heaters allows for the provision of more inside space.
  • Tankless water heater venting styles allow for a variety of emission options to be selected.
  • Fourth, condensation tankless water heaters reduce the monetary worth of the installation by a significant amount.
  • The use of tankless water heaters with a coaxial vent type provides additional safety benefits.
  • 6.

These arrangements allow water heaters to be integrated into their respective building frames rather than being suspended from the side. 7. Pipe coverings and ingenious termination positions provide visually pleasant emission-control options.

Frequently Asked Questions

In order to properly vent a tankless water heater, you should keep the following guidelines in mind: 2. If a tankless water heater is put indoors, it will draw in air from the outside. Water heaters that do not require a tank are vented in one of two ways: by using the power vent or by using the direct vent. When put in a big enough area, direct-vent units will draw in outside air from the home or building, but power-vent units will only require an exhaust vent and will need to be installed in a smaller area to get a sufficient amount of outside air for burning.

  1. It is environmentally friendly to install a tankless water heater outside since it eliminates the need for additional emissions.
  2. Fans in tankless water heaters direct the flow of exhaust away from the heater horizontally, allowing vents to be located in a variety of locations throughout your home.
  3. Another element that detracts from the overall value of the installation is the use of PVC or plastic as an exhaust vent, rather than metal.
  4. It is more likely that the air will remain within the coaxial vent rather than entering the home if a pipe leaks.
  5. These arrangements allow water heaters to be integrated into their respective building frames rather than being suspended from the side walls of a structure.
  6. Pipe coverings and ingenious termination locations provide visually beautiful emission control options.

American Tankless Water Heaters Venting Guide

ANSI Z223.1/NFPA 54 (National Fuel Gas Code, current edition) in the United States and/or Section 7 of the CAN/CSA B149.1 Natural Gas and Propane Installation Code (Canada), as well as any applicable municipal building requirements, must be followed while venting the water heater. The following are the general principles for venting water heaters:

  • Install the water heater as near to the vent terminator as practicable. The heater’s vent collar must be secured directly to an unobstructed vent pipe in order to function properly. Welding the vent pipe to the water heater’s vent collar is not recommended. It is not necessary to cut the vent collar of the unit. The vent must be easily detachable from the top of the water heater in order to do routine maintenance and inspections on it. The water heater vent must not be linked to any other gas appliance or vent stack
  • Otherwise, the water heater will fail. AVOID utilizing an oversize vent pipe or running the pipe for excessively extended lengths of time. Rain caps or other forms of termination that prevent rainwater from entering the water heater must be fitted if rooftop venting is being used. No other appliances or common vents should be connected to the water heater vent
  • This includes any other appliances that have a vent.

Diagrams of Ventilation Installation Tankless water heaters in the United States of America

Your Tankless Water Heater and Its Venting Requirements

Installation of a tankless water heater in your house to save money on your utility costs may be something you’re thinking about doing. Despite the fact that tankless water heaters are practical and take up little space, the installation of gas-fueled devices is more complicated than the installation of a standard water heater. Tankless water heater venting must be done appropriately in order to ensure the unit’s safe and effective performance over its lifetime. For proper tankless water heater venting, your installation should take into consideration the following factors:

  • There is no shared venting
  • Only venting to the outside. The tankless heater is not permitted to share vent pipes with any other appliance, and it is not permitted to vent via a brick chimney flue. Pipe made of stainless steel in particular. The vent pipe must be constructed of stainless steel that has been specially treated to handle corrosive gases. If the tankless heater vented through the usual galvanized vent from your previous storage tank heater, the galvanized vent would rapidly rust away
  • However, A downhill slope or a condensate drain can be used. It is recommended that your vent slope slightly downhill from the water heater’s heat exchanger or that it be built with a condensate drain near the exhaust exit to maximize efficiency. This prevents condensate from re-entering the heater through the drain pipe. Failure to keep the heat exchanger free of corrosive condensate will result in the exchanger’s life being cut short by many years. Vent run is brief. The length of the vent should be as short as feasible in order to ensure full exhaust of combustion gases from the residence. It makes financial sense to locate the tankless heater closer to where the stainless steel vent pipe will exit the home since stainless steel vent pipe is significantly more costly than gas supply and water supply pipes. You will require less vent pipe in this manner, despite the fact that you will require more water and gas supply pipes.

There is no shared venting; all venting is directed to the outside. No other appliance can share the tankless heater’s venting system, and the tankless heater cannot be vented using an existing brick fireplace’s flue; stainless steel pipe that has been specially manufactured Stainless steel vent pipes, which are intended to expel corrosive gases, must be used for this purpose. If your tankless heater vented through the conventional galvanized vent from your previous storage tank heater, the vent would rapidly rust away.

This prevents condensate from re-entering the heater through the drain.

Only a short vent run is necessary.

It makes sense to locate the tankless heater closer to where the stainless steel vent pipe will exit the home because it is significantly more expensive than the gas supply and water supply pipes. Even though you will require more water and gas supply piping, you will use less vent pipe this way.

Do Tankless Water Heaters Need to be Vented?

When shopping for a tankless water heater, it’s important to understand that both interior and exterior types are available. It is the way in which they are vented that is the most significant distinction between the two types. When it comes to gas tankless water heaters, consumers frequently have questions about venting. Exterior gas types feature vents along the front of the unit, which makes them unsuitable for use inside a building. If you’re not attentive, you may end up with a tankless water heater that is too small for your family’s requirements.

  1. Do tankless water heaters have to be vented in order to function?
  2. All indoor variants are equipped with an exhaust vent.
  3. Direct vent types bring in fresh air directly from the outside and may be placed in tight locations with no difficulty.
  4. Do you require the services of a Licensed Plumber?
  5. Get a free quote from top-rated, pre-screened, and licensed plumbers in your region right now.
  6. Electric tankless water heaters do not require venting, therefore they may be installed almost anywhere without the need for additional ventilation.
  7. Carbon monoxide poisoning, which is exceedingly damaging and sometimes lethal, can occur as a result of a shortage of oxygen in the atmosphere.
  8. Maintain your interest to learn more about how to go about setting up a tankless water heater that is both safe and efficient.

Tankless Gas Water Heaters that Need to be Vented

Tankless natural gas or propane water heaters are extremely energy efficient, lowering energy consumption by up to 50% while also providing the significant benefit of reducing greenhouse gas emissions by up to 61 percent. Although they must be properly vented in order to attain such efficiency and usefulness, in addition to meeting all safety criteria, they must be properly vented. Tankless water heaters are put in a variety of locations depending on the kind of intake venting used: direct vent or power vent.

  • They may be vented through an outside sidewall or roof; however, you must choose the quickest route available to do this.
  • For tankless water heaters, a specific stainless steel vent pipe is employed, which will not corrode when corrosive gases are vented via it.
  • Insider Tip: Tankless water heaters are not permitted to share a vent with a furnace or to vent through a chimney flue.
  • Tankless water heaters with a concentric vent design of 5 inches in diameter have intake and exhaust venting pipes built in.
  • This also provides an additional layer of protection from hazardous gasses.
  • In order to avoid hanging non-condensing tankless water heaters from the wall framing, several manufacturers provide recess boxes that allow them to be installed inside the wall frame rather than hanging off the wall.
  • It is significantly more easy and cost-effective to install venting via a sidewall than than through the roof, as is the case with many classic gaswater heaters, as long as the piping can be accommodated.
  • This allows them to be installed outside in warmer climates where they would otherwise be inaccessible.
  • While non-condensing tankless water heaters are smaller and more suitable with most recess boxes, with an average width of 14 inches, condensing boxes, with an average width of 18 inches, provide a number of advantages over non-condensing tanks.
  • This implies that the exhaust from a condensing tankless water heater is colder, ranging between 110 and 120 degrees Fahrenheit.

It is most effective to install tankless water heater venting with a little slope from the heat exchanger and condensate from the drain near the exhaust, which prevents draining back into the heater and extends the unit’s lifespan.

Tankless Water Heater Vent Types

There are several different types of vents for tankless water heaters, each with a unique set of capabilities, price ranges, installation requirements, and advantages. Listed below are some examples. The most appropriate vent would be heavily reliant on the tankless water heater’s location and size, as well as the need for air intake and the available space.

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Power Vent

Power vent units make use of the air that is already present in the home for combustion, and they function by venting the air outside for regulating. A single exhaust vent is required for power vent units as a result of this feature. Power vent units Because of the potential for spatial limits in the surrounding area, these units require a bigger room with enough ventilation.

Direct Vent

Direct vent units feature two vents, one of which serves as an intake vent, drawing air into the building from the outside, and the other as an exhaust vent, drawing air out of the structure. Direct vent devices are equipped with two vents and rely on outside air to work properly. The use of direct vent units allows for the installation of units in smaller spaces, such as closets, with less extra air in the local environment. This may save up to around 16 square feet of floor space, making them a great alternative if you have a limited amount of floor space to work with.

Concentric Vent

Concentric vents are essentially two vents in one; a single vent that incorporates both intake and exhaust direct-vents in the same space. Concentric vents are frequently offered by manufacturers in order to attain the finest characteristics of both power vent and direct vent devices. Concentric vents give the convenience of having a single pipe that serves as both an exhaust vent and a direct intake vent in one package. One hole in the sidewall or ceiling, as well as the fact that temperatures are regulated because warm exhaust air remains inside, which keeps them cold to the touch, are all advantages of this design.

  1. Direct vents are quite hot to the touch, whereas concentratic vents are not.
  2. While they do provide a number of advantages in terms of safety and convenience, it should be noted that concentric vents are bigger in size, with pipes often measuring approximately 5 inches in diameter, as compared to the conventional 3 inches in diameter for single pipes.
  3. An effective ventilation system is essential for maintaining the safety, functioning, and comfortability of a building’s interior environment.
  4. No other equipment, including a furnace or a water heater, may share a vent with a tankless water heater.
  5. For the venting of gas tankless water heaters, a stainless steel vent is the most appropriate choice.

The ability to install many tankless heaters without having to add new permeations to the building’s construction is a major advantage, but it should only be used if it has been determined by an expert specialist to be an appropriate alternative.

Can You Use the Existing Vent for the Tankless Water Heater?

For the same reason that you won’t be able to use the existing vent pipe from an old gas tank water heater to vent a tankless water heater, you won’t be able to use the existing vent pipe from an old gas tank water heater. The present vent for tankless water heaters is incompatible since the majority of it is galvanized vent pipe, which rusts fast when exposed to moisture. Special stainless steel pipes should be used for venting, unless the vent manufacturer’s recommendations indicate that plastic materials are adequate for the application.

Do Electric Tankless Water Heaters Need to be Vented?

Electric tankless water heaters, in contrast to gas or propane tankless water heaters, do not require any venting. Electric tankless water heaters heat water quickly with the use of electric burners. Because no natural or propane gas is utilized, there is no requirement for venting. Some of the most prominent aspects in the rising popularity of electric tankless water heaters are their efficiency, convenience, and general adaptability for many applications. Due to the fact that electric tankless water heaters do not require venting, they lose less heat than their gas counterparts.

Electric versions have the disadvantage of requiring a 240v circuit for each burner, which is inconvenient for some people.

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Tankless Water Heater Venting Options

Are you considering purchasing a new tankless water heater? When someone inquires about how to vent a tankless water heater, they are most likely inquiring about the sort of venting system that should be installed. Once you have a strategy in place, the task is rather basic.

All that’s left to do is connect ductwork between the unit and the termination, which is rather straightforward. So, what are your alternatives for tankless water heating systems? In the end, it comes down to three options and determining which is best for you:

  1. A new tankless water heater may be what you’re looking for. When someone inquires about how to vent a tankless water heater, they are most likely inquiring about the sort of venting system that should be put on the tankless water heater. Having a strategy in place makes the process relatively uncomplicated. All that’s left to do is connect ducting between the unit and the termination, which is a simple process. How do you go about choosing a tankless water heating system? To summarize, it comes down to three options and determining one is best for you.


A tankless water heater with a direct-vent layout requires two vents: one on the top and one on the bottom. Direct-vent systems have the substantial benefit of being able to be installed in smaller places due to the fact that they draw in air from outside the home. Direct-vent systems, on the other hand, have limitations in terms of where they may be put within a structure. In other cases, direct venting may not be possible since the installation location is located a great horizontal distance from the termination point.

It is on the bottom level of a major business building, in the midst of it, that you are most likely not to spot them.


Because power-vent systems demand a sufficient volume of air, they necessitate a larger installation space. One of the most significant advantages of power-vent is that just one exhaust vent is required. With the power exhaust, the tankless water heater unit is capable of operating over extended distances away from the termination point without losing efficiency. So this is what you would put on the bottom level of a large commercial facility in the midst of it if there is enough ambient air in that position.

Think Outside the Box (House) with Your Tankless Water Heater Venting Options!

Was it ever brought to your attention that you may install an outdoor tankless water heater? This may only make sense in warmer areas, according to some experts. They are constructed with components that will keep them warm in the winter. If your water heater is situated outside, there is no need to use any type of ventilation system. The problem has been resolved!

Use Quality Components

Whatever you decide, be sure to choose reputable brands for tankless water heaters, ducting, and any other components and accessories that you may require to complete your job. We offer fantastic discounts on Bradford White, Noritz, and Takagi. Please call for details. Please do not hesitate to contact us if you have any further concerns regarding tankless venting solutions or anything else pertaining to this subject. Resources that are related to this topic include: Installing a Tankless Water Heater – Step by Step Instructions How to Flush a Tankless Water Heater (with Pictures) How to Reset a Tankless Water Heater (with Pictures)

Tankless Water Heater Venting – Installation Tips

Whatever your situation is, whether you’ve purchased a tankless water heater or are looking for pertinent information regarding on-demand heating systems, the installation requirements for the venting system are something you should carefully consider. The appropriate selection of the heater type may assist you in lowering your utility costs, lowering your energy consumption, and saving time during the installation process. Before you make the decision to purchase an on-demand heater, take the time to review the accompanying advice, suggestions, and venting requirements.

Venting options in tankless water heaters

  • Whether it’s indoors or out, Power venting or direct venting are also options. Termination can be either horizontal or vertical. Venting can be done using two or one pipes. Venting made of stainless steel or PVC

Do I need venting for my water heater?

A venting system is required for any gas-powered tankless water heater that is put inside the home, but an electric tankless water heater does not. Vents are intended to securely transport exhaust gases to the outside. This covers typical tank-type gas heaters, as well as other types of gas heaters. Every gas-powered machine generates heat by burning natural gas or propane, depending on the model. This is taking place within the combustion chamber, thanks to the use of the gas burner. As the unit releases energy to heat water, it also emits exhaust gases into the surrounding environment.

Purchase carbon monoxide detectors to ensure the safety of your family.

Tankless water heaters typically use one of the following venting systems to properly evacuate the gases: power vent, direct vent, or a combination of the two.

This is true for tankless units intended for indoor installation; however, outdoor variants do not require a venting system because they are already placed outside of the home.

What do you need to know about tankless venting

When it comes to combustion, gas tankless water heaters can use either interior or outside air, and the exhaust gases must be able to easily go to the outside atmosphere with no blockages or leaks. According to the previous section, there are two types of venting systems that may be utilized with tankless water heaters: power-vent and direct-vent. Power-vent water heaters burn gas by utilizing inside air, whereas direct-vent water heaters burn gas by utilizing outdoor air. Power-vent models have an exhaust fan and just one pipe, which is for exhaust, whereas direct-vent models have two pipes, one for air intake and the other for exhaust, with the former being the more common.

  1. It is required that two air apertures with the necessary widths and distances from the floor and ceiling be provided if the water heater is located in a confined location (i.e., if the space volume is less than 50 ft.
  2. Direct-vent setups in which the tankless uses two pipes have the option of installing two distinct pipes (two-pipe system) or a single pipe with the concentric (coaxial) arrangement, also known as a pipe inside a pipe, in which the tankless employs one pipe.
  3. This configuration allows the vent to remain cool to the touch, hence reducing the danger of burn injuries.
  4. Even if there is a leak in an exhaust pipe, the hazardous gas is kept within the circular vent, ensuring that it does not damage the environment or negatively impact your health.
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Indoor or outdoor

Tankless-indoor Indoor tankless water heaters must vent exhaust gases to the outside atmosphere using one of the two types of vents stated above: power vent or direct vent (see diagram). A special kit is required for outdoor installation if the units are to be put outside (where applicable). There are vent slits on the front panel of the outdoor variants, so they do not require extra vents. Tankless-outdoor-Find Local Plumbers – Find a Plumber in Your Area –

Typical installation and how to configure vents

Tankless indoor concentric heating and cooling Tankless-indoor, 2 pipe configuration Tankless vents are typically available in three and four inch widths. The vents are linked to the device using a vent adapter that is included with it. The tankless indoor water heater is often vented horizontally through a sidewall or vertically through the roof, depending on the manufacturer’s recommendations. When compared to the traditional vent installation of tank-type water heaters, tankless water heaters offer greater flexibility and are less expensive, particularly when sidewall installation is required during a home renovation project.

  1. Exiting the tankless unit vertically, the vent will be turned 90 degrees and then straight, pointing downward (1/4 inch each foot) and out the front door.
  2. This is the most straightforward configuration.
  3. When acidic condensate is present, these two approaches are employed to safeguard the water heater from further harm.
  4. The condensate should not be discharged through the heater, but rather through the trap.
  5. Especially if you live in a hotter area, outdoor models are an excellent choice because they don’t require any additional ventilation and free up valuable interior space for other purposes.
  6. Because tankless water heaters are frequently paired with a heating system that automatically supplies heat, you are even safe if you live in a location with temperatures below freezing.
  7. Condensing heaters, on the other hand, may be vented through PVC and PP pipes, which are both less expensive and easier to install (and handle).
  8. The number of elbows is limited due to the fact that they lessen the overall distance between the vents.
  9. Because they may utilize a manifold to share the same vents, there is no need for separate vent penetration, which saves you both time and money during the installation process.

Furthermore, having fewer wall holes is both more functional and more visually pleasing. Tankless-common venting is a kind of common venting.

Useful tips

  • Installing required supports (pipe hangers) in horizontal venting will help to prevent dips and sags. Whenever feasible, venting should be installed as directly as possible, with the smallest amount of pipe bends. The connections between the vents should establish an airtight seal in order to avoid gas leakage. Using an existing chimney as a connection point for the venting system is not advised. Try to avoid placing the vent termination near other vents or exhaust. Make sure to follow the manufacturer’s recommendations for distances between things (such as windows and doors, the ground, walkways, and so on)
  • The air used in combustion must be devoid of corrosive substances. Annual inspection for leaks, blockages, and other damage to the vent system is recommended. The presence of white smoke emanating from the exhaust vent is typical. Avoid utilizing vents that are longer than recommended and vent pipes that are too large. Vents that terminate at the roof should be equipped with a rain cap or another form of cover (90+45 bends)

Caution: Improper venting of any gas water heater can result in carbon monoxide leaks and poisoning of those around you.

Manufacturers of vent components

There are three types of venting systems often used in home water heating: atmospheric, direct-vent, and power-vent. The first two are the most common. They utilize flue ducts or a chimney to exhaust the exhaust gases from the water heater and vent them to the outside. Flue ducts can be made of metal or plastic, depending on the venting method being used.


A tankless water heater may be a fantastic investment for your house since it provides unlimited hot water while also operating at a high level of efficiency. However, tankless hot water heaters, like any other item, can develop problems over time and require maintenance. If you currently have a tankless water heater or are thinking about getting one, here are some typical problems you could run into and how to fix them the right way:

Problem1: blocked exhaust or vents

An error number is displayed on the majority of tankless water heater displays to indicate that the exhaust or intake air supply has been cut off – an indication that your heater is having venting or combustion problems. Identification of all exhaust and intake lines and a visual inspection to ensure they are securely connected and in excellent condition with no holes are required to diagnose the problem. Ensure that your heater is not too close to any object that might obstruct the air supply or provide a fire hazard as a result of this.

Problem2: overloaded system

An excessive amount of simultaneous hot water demand might cause your system to become overloaded (i.e. multiple faucets, appliances or showers running at once.) This might cause the unit to work harder to provide the hot water that is required, or it can cause the unit to totally shut down. If this occurs, minimize the demand for hot water by minimizing the number of simultaneous uses, and then reset the water heater. Allow the water heater to reset for a short period of time, and if the problem persists, contact a specialist.

Problem3: mineral deposits

It is typical for water systems to have trace amounts of magnesium and calcium. Magnesium and calcium are two of the most prevalent minerals that induce scale build-up in tankless water heating systems. Mineral deposits can have a negative impact on the overall performance and efficiency of your water heater, as well as significantly limit its lifespan if they are not removed. Check the manufacturer’s guidelines for eliminating mineral buildup; most advocate frequent flushing and descaling to keep the system running smoothly and efficiently.

Try flushing and descaling the system yourself if you’re handy, but make sure to read the manufacturer’s instructions thoroughly first. If you live in a region with very hard water and find yourself unable to keep up with the mineral buildup, you may want to consider installing a water softening.

Problem4: flame failure or no ignition

There is a good chance that your tankless water heater is experiencing an ignition problem if it is displaying an error code such as “Flame Failure” or just not starting up properly. The majority of ignition failures are caused by problems with the gas supply/pressure or the gas valve. You should get assistance from a certified specialist if you believe the problem is related to the ignition.

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There is a good chance that your tankless water heater is experiencing an ignition problem if it is displaying an error code such as “Flame Failure” or just not firing up correctly. Gas supply/pressure and/or gas valve failures are the most common causes of ignition failures in most situations. For assistance in addressing an ignition problem, we recommend that you seek the advice of a licensed specialist.

How to Vent Your Tankless Water Heater Correctly (Demo)

The Correct Way to Properly Vent Your Tankless Water Heater (HomeBlog) (Demo) The method through which you vent your tankless water heater is one of the most significant considerations when installing your tankless water heater. It is important to properly vent a tankless water heater in order to maintain optimal operation and to extend the lifespan of your device. Choosing tankless water heating for your family’s water heating needs has a number of advantages, including conserving resources, lowering your monthly expense, and reducing extra waste.

Tankless water heaters are recognized for saving households money since they are not continually running and reheating large volumes of water, but they also save energy because they only turn on when they are required.

Tankless water heaters that are gas-fueled, on the other hand, might have their own set of problems if they are not placed properly, such as failing to live up to their projected lifespan due to inadequate venting.

Tankless water heaters provide the option of venting horizontally (through a side wall) or vertically (through the roof).

As a result, many homeowners choose to relocate their heater closer to an outside wall and run water lines to it instead of installing a tank.

The specific stainless steel venting material also contributes to the system’s ability to tolerate the positive pressure it generates.

When dealing with something as dangerous as gas and carbon monoxide, it is important to install your tankless water heater correctly the first time in order to reduce the likelihood of inefficiency as well as the risk of injury.

Extra care taken in the right installation of your venting will spare you the bother of having to worry later about whether or not your tankless water heater is securely draining condensate and expelling gasses.

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