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Direct Vent Water Heaters, Buying Guide and Installation Tips

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

In this guide we will take a look at direct vent water heaters.  We’ll look at some of the best models of direct vent water heaters available on the market today, and the features and benefits of each of them. 

We’ll also take a detailed look at how they work, what different types of water heaters do, and how different types of water heaters need to be installed.  

We will explore some of the biggest direct vent water heater manufacturers and their best models, including Rheem, Bradford White, and AO Smith. 

Since fuel prices have risen dramatically over the recent years, and they continue to do so, many people are looking for a more economical option.  Energy from water heating typically accounts for approximately 20% of our bills, so it makes sense to search for a better option.  That’s why we’re here to help. 

If you want to learn how water heaters work, then you’re in the right place.  We’ll also teach you about the main parts of direct vent water heaters, as well as the requirements for installation.  Additionally, we’ll look into the costs of service and maintenance. 

It is essential that you consider the correct location and venting for a direct water heater, regardless of the type of unit or fuel, and regardless of whether your house is modern or traditional. 

When buying an electric water heater, however, you don’t need to concern yourself regarding venting, combustion gases, or extra expenses.

Venting Types 

Water heaters that have tanks come with one of four types of vents.  These types of vents include standard/atmospheric, direct vent, power vent, and power-direct vent.

Regardless of the vent type you choose, you must ensure that it has some kind of ventilation system in order to remove flue gases and air for gas combustion. 

Choosing the ideal type of vent is dependent on the location of the water heater, in addition to the installation requirements.  Local building regulations may also influence the type of vent you will need. 

The most common type of venting in water heaters are atmospheric.  This is because they are the least expensive to buy, and they are relatively straightforward to install. 

They feature a vertical pipe or chimney to allow the flue gases to move up through it.  This pipe is typically made of metal.  This works because the hot air rises up from the unit due to the difference in pressure. 

Power-vent water heaters use an electric blower to blow out the exhaust gases through a pipe to the outside of the building.  The pipes these types of vents use are typically made from ABS, CPVC, or PVC. 

Units with this type of vent system are generally more expensive than those with an atmospheric venting system.  They do, however, provide a greater degree of flexibility in terms of their installation, because the electric blower helps to remove the exhaust gases.

Water heaters that feature a power-direct vent system are a hybrid between power and direct vent water heaters.  Like the power-vent water heaters, they also use a blower to transfer gases from the unit to the outside. 

These types of water heaters are typically used when the unit is located far away from an external wall, thus needing longer pipes. 

Direct vs. Atmospheric VS Power Ventilation 

In order for them to properly ignite, direct vent water heaters need enough fresh air to provide oxygen to the flame.  This fresh air comes in, for the most part, through the venting pipe from the outside.  

Direct vent water heaters use sealed combustion chambers to create a safe transfer of gases that are created during combustion.  These gases are transferred through a horizontal pipe, and to the outside through an external wall.  A second airtight pipe is also used for fresh air to be brought into the combustion chamber. 

Atmospheric water heaters face a couple of problems that direct vent water heaters solve.  These two problems are back drafting in addition to negative pressure inside the room in which the unit is located.  

Direct vent systems tent to be a lot less noisy than power vent systems as they don’t contain an electric blower.

Venting pipes must be installed in accordance with local regulations and per the manufacturer’s guidance.  

Direct Vent Water Heaters, Buying Guide and Installation Tips1

Direct Vent Water Heater Buyers’ Guide

Here are some guidelines and advice for purchasing direct vent style water heaters.  These tips and recommendations will help you make an informed purchase decision.

No Chimney Required 

If your house does not feature a chimney or there is not one located in the vicinity of the water heater, or there is no access to electricity nearby, you will require a direct vent water heater. Since these types of water heaters don’t need access to electricity, you will still be able to access hot water during power outages. 

If access to electricity is not a factor, you may prefer a more advanced direct model of water heater that features an electric blower to aid in the transferal of exhaust gases to the outside. This type is called power-direct vent system. 

Direct venting systems tend to be more reliable than power venting systems as they don’t suffer from pilot outages caused by changes in air pressure.  

Gas water heaters with a direct vent feature sealed, airtight combustion chambers which prevent back drafts.  They are also much quieter than power-direct models, as they don’t feature an electric blower. 

There is also very little risk of the carbon monoxide getting out from the unit die to insufficient ventilation.  These systems can be installed pretty much anywhere as long as it’s nearby and outside wall and fresh air can be drawn in from outside. 


The recommended pipe length determines how close a direct vent water heater can be installed to an outside wall.  This tends to vary depending on the manufacturer’s guidelines.  Direct venting systems can be found in tank as well as tankless water heating units. 


Direct vent water heating systems are generally very safe due to the sealed, airtight combustion chamber.  This prevents dangerous gases and fumes from entering the space inside the house. 

These units always operate with fresh air from outside, rather than using air from inside the house.  There is no cause for concern over the use of direct vent water heating systems. 

Ease of Installation

Typically speaking, direct cent water heating systems come with steel pipes, but others may use ABS, CPVC, or PVC pipes (see also ‘How To Cut PVC Pipe As Pro‘) as they are more economical and easy to work with. 

These pipes can either be installed vertically or horizontally, depending on the requirements of installation and the specifics of the location. 

Vertical pipes are generally favored as the hot gases rise up and out naturally.  Horizontal pipes, on the other hand, require direct venting with fewer turns and pipe fittings.  This allows for the unit to be installed in a smaller space.  

Top Direct Vent Water Heater Manufacturers

More often than not, North American manufacturers of water heaters use direct venting systems.  The following manufacturers are some of the most popular and well-known makers of direct vent water heaters. 


Rheem are a popular and well-known manufacturer of water heaters.  Their products include many types of direct vent water heaters.  They typically feature a coaxial vent as this provides easy installation particularly is residential properties.  

Their range of direct vent heaters feature a horizontal vent that is available in either 40 gallon or 50 gallon capacities.  This coaxial vent can be adjusted as it is able to swivel a full 360 degrees. 

This provides a lot of flexibility when it comes to installation.  Both the horizontal and vertical versions are available for 48” of venting at the most.  

Rheem models use a patented Rheemglas lining in their tanks to protect against corrosion.  Additionally, they contain an anode rod, and a system to prevent the build up of sediment called EverKleen. 

The Rheem PROG50-36N RH60 DV is their 50 gallon model.  It is part of the Professional Classic series.  It has a recovery rate of 35.5 GPH, a first hour delivery of 50 GPH and it’s energy factor is 0.51. 

A comparatively better model with improved specifications is the XG50T06DV36U0.  This model also has a 50 gallon capacity, and it is part of Rheem’s Performance Series.  This model features a recovery rate of 36.4 GPH, a first hour rating of 78 GPH, and its energy factor is 0.63.

AO Smith

AO Smith are a manufacturer of water heaters that have comparatively a wider variety of different models than Rheem does.  They are available in both natural gas or propane. 

They use a low NOx gas burner.  Additionally, all of AO Smith’s water heaters come with a 6-year warranty as standard.  

AO Smith’s water heating systems do not require an electricity source to function.  They also have direct vent options available for their own manufactured housings. 

The AO Smith GDVT-50 is their finest water heater that the manufacturer makes.  It has a capacity of 50 gallons, and it features a 47,000 BTI gas burner.  This gives an energy factor of 0.65, a first hour rating of 83 GPH and a recovery rate of 51 GPH.  

The AO Smith GDV-50, on the other hand, is a weaker gas powered water heater which provides a power of 40,000 BTU.  This model also provides a lower first hour rating 77 GPH, and a recovery rate of 43 GPH.  This model’s energy factor is slightly higher, however, with a rating of 0.66. 

Bradford White

Bradford White’s Defender Safety System models feature a coaxial vent as we described earlier in the article.  This is designed in particular for houses where there is insufficient air to provide proper combustion for gas. 

The pipe can also swivel to provide flexibility when installing the unit.  They also have telescopic vent kits which can be up to 8 feet in length, while the flexible vent kits are available up to 100” in length. 


The various different types of vent systems as we have described above must be installed by professionals in accordance with local building regulations and as per the manufacturer’s guidance. 

This allows for the safe and efficient use of these units.  Since these types of vents do not have a blower, they must have a clear pipe for proper ventilation.  

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Charlie Hardcastle


On Key

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