Knowledge Builders

are all tankless water heaters direct vent

by Mr. Carter Fadel V Published 4 months ago Updated 2 months ago
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To remove the gases safely, tankless water heaters usually utilize one of the following venting types: power or direct vent. This applies to tankless models designed for indoor installation, while the outdoor models do not require a venting system because they are already installed outside.

Full Answer

Is a tankless electric water heater worth it?

Rewiring your house can easily add as much as $5,000 to the cost of installing a tankless water heater. Tankless models save space, offer longer warranties. Many homeowners, however, see benefits of a tankless water heater beyond energy savings. These heaters also save space with a compact design, last longer and are better for the environment because a rusty tank doesn’t end up in the landfill.

Are tankless heaters worth it?

Tankless water heaters are typically quite pricey, especially if you have to go after a particular model depending on how your RV is set up. If you only take your RV out a few weekends each year, it probably isn't worth spending the extra money.

Are tankless water heaters too expensive?

Tankless water heaters can get very expensive, but the Thermoflow Elex 3.5 is a very affordable option that won’t break the bank. Despite the low cost, it’s an effective unit, which is why it’s our pick for the best value. It’s a very small device, measuring just 8”X 6”X 3”.

Can tankless water heaters save money?

While it may cost more upfront, a tankless water heater will help you save a lot of money in the long run since it only heats on demand and requires minimal repairs. On top of that, it has twice the warranty period compared to a traditional water heater.

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What type of vent does a tankless water heater use?

Tankless water heaters can be vented in two ways: power-vent or direct-vent. Power-vent units use indoor air for combustion and simply vent the exhaust to the outside. Direct-vent units pull in air from the outside, so they have two vents for intake and exhaust.

Do all tankless water heaters need to be vented?

No. Unlike gas tankless water heaters and gas traditional tank style water heaters, electric tankless water heaters do not require any venting. This is often one of the deciding factors when choosing whether you should purchase a gas or electric tankless water heater.

What is non direct vent tankless water heater?

Non Direct Vent Indoor (Fan Assisted) Uses an electric fan (or blower) to push flue gases to the outdoors. Pulls oxygen needed for combustion from the inside space. Fan assisted indoor gas appliance design allows for horizontal or vertical venting.

What is the best way to vent a tankless water heater?

Tankless water heaters can vent through the roof or a side wall, creating more flexibility and options for placement. Traditional gas tank water heater require venting through the roof. Tankless water heaters use fans to blow exhaust from the unit horizontally, allowing vents to terminate on the side of a house.

Can tankless water heaters be vented with PVC?

In most cases, PVC makes a great venting material. It's the least expensive option and is easy to install. And it's a good reason to consider a high-efficiency condensing unit.

Does a tankless water heater need a power vent?

Indoor gas tankless water heaters need to be vented. All indoor models have an exhaust vent. Indoor models also need a fresh air intake either from a direct vent or a power vent.

How do I know if my water heater is direct vent?

Difference in terms of venting pipe: A power vent water heater exhausts the gases or fumes through a PVC or other plastic pipe venting. A direct vent water heater does that through metal venting.

Why are direct vent water heaters so expensive?

Direct venting systems work well whether there is electricity or not. Power vent water heaters have more moving parts, which makes them more complex and costlier to install. They can use either a vertical or horizontal vent pipe as the blower or fan provides the momentum to move the exhaust gases.

Whats the difference between a condensing and non condensing tankless water heater?

Condensing tankless heaters use a dual heat exchanger design to make maximum use of the energy delivered to the system. Non-condensing tankless water heaters utilize a single heat exchanger so they vent more heat in the exhaust gases.

Can you vent a tankless water heater and furnace together?

When installing a tankless water heater, you have to consider the type of heater to guide you on what kind of venting you will need. Since a high-efficiency gas water heater produces corrosive combustion gases, you should avoid connecting it with the furnace vent or other existing vents for other appliances.

How far does a tankless water heater vent need to be from a window?

Indoor Installations A tankless water heater requires a 4-foot clearance from the side or below a door or window that opens, unless the unit is directly vented to the outside, says Ernie Graves. If the water heater is installed above the door or window, it needs 12 inches of clearance.

Is it OK to put a tankless water heater in the attic?

Simply put, as long as there is enough combustion air provided, tankless water heaters can be installed in any area of your home, from a utility room to a garage to, yes, even an old, dusty attic.

Can a tankless water heater be enclosed?

Electric tankless water heaters are designed to be installed indoors in the garage, basement, or interior wall. Both natural and propane gas tankless water heaters have indoor and outdoor models. Indoor models can also be installed in the garage, basement, or the exterior wall's interior side to provide venting.

What is the difference between condensing and non condensing tankless water heaters?

Condensing tankless heaters use a dual heat exchanger design to make maximum use of the energy delivered to the system. Non-condensing tankless water heaters utilize a single heat exchanger so they vent more heat in the exhaust gases.

Can you vent tankless water heater with furnace?

When installing a tankless water heater, you have to consider the type of heater to guide you on what kind of venting you will need. Since a high-efficiency gas water heater produces corrosive combustion gases, you should avoid connecting it with the furnace vent or other existing vents for other appliances.

Can a tankless water heater be installed in a closet?

Your tankless water heater can be installed just about anywhere! Due to the small size of your water heater, it can be mounted in many small spaces, including closets, under sinks, in pantries, or under stair storage areas.

How efficient is tankless water heater venting?

Tankless water heater venting is most efficient when installed with a slight slope from the heat exchanger and condensate from the drain near the exhaust, which prevents drainage back into the heater and prolongs the lifespan of the unit.

How big is a tankless water heater?

While non-condensing tankless water heaters are smaller and compatible with most recess boxes at an average size of 14 inches in width, condensing boxes larger at around 18 inches in width have many benefits. Condensing tankless water heaters are approximately 95% more efficient than non-condensing types, which only transmute around 80% ...

How many tankless units can be installed in a common vent?

However, modern common-venting systems utilize manifolds to share the same exhaust and intake vents for up to eight tankless units. This is great for installing multiple tankless heaters without adding additional permeations in the building’s structure but should only be installed if it’s determined to be a suitable option by an experienced professional.

What is a concentric vent?

Concentric vents are 2 vents in 1; a single vent that actually contains both intake and exhaust direct-vents. Manufacturers commonly offer concentric vents to achieve the best qualities of both power vent and direct vent units.

What is a concentric vent in a tankless water heater?

Tankless water heaters with a 5-inch concentric vent design contain both intake and exhaust venting pipes. The vent design keeps the vent cool because the warm exhaust vent is insulated inside. This also adds a layer of protection from harmful gasses. The concentric vent keeps harmful gasses from entering the home if the exhaust pipe inside starts leaks.

How much does a tankless water heater reduce energy?

Tankless gas or propane water heaters are absolutely fantastic for efficiency as they can reduce energy by up to 50%, in addition to the major bonus of it reducing greenhouse gas emissions by up to 61%. But, they do need to be vented properly to achieve such efficiency and functionality in addition to safety requirements.

What type of pipe is used for tankless water heaters?

A special stainless steel vent pipe is used for tankless water heaters that won't damage from venting corrosive gases. The standard galvanized vent used from tank water heaters, or furnaces will rust quickly when venting a tankless heater.

What type of vents are used in tankless water heaters?

As mentioned before, there are two types of venting systems used on tankless water heaters: power-vent and direct-vent. Power-vent water heaters use indoor air for gas combustion, while direct-vent utilize outside air. A power-vent model comprises an exhaust fan and only one pipe, which is exhaust, while a direct-vent model has two, ...

What size vents are needed for a tankless air conditioner?

The most typical sizes of tankless vents are 3" and 4". The vents are connected to a vent adapter that comes with the unit.

How to protect water heater from acidic condensate?

If you have a condensing tankless water heater, slope the venting ¼” per foot and toward the heater. The condensate should not drain through a heater but the trap.

What is a coaxial vent?

The coaxial type consists of an insulated intake pipe with 5 and 4 inches in diameter and exhaust pipes with 2 and 3 inches, which enable the vent to remain cold to the touch , therefore, preventing the risk of burn injuries.

What is the purpose of selecting a heater type?

The proper selection of the heater type can help you reduce utility expenses, lower energy consumption, and save you time on installation. Before you decide on buying an on-demand heater, consider the following guide, tips, and venting requirements.

How many pipes does a direct vent have?

A power-vent model comprises an exhaust fan and only one pipe, which is exhaust, while a direct-vent model has two, one for air intake and the other for exhaust.

Why are there limited elbows for vents?

Note: Every manufacturer specifies the maximum lengths that you can run the venting. The number of elbows is limited because they shorten the total vent distance.

Direct-Vent

A tankless water heater with a direct-vent configuration requires two vents:

Power-Vent

Power-vent installations need adequate air quantity, so they require more installation space. The major advantages of power-vent are that you only need one exhaust vent. With the power exhaust, the tankless water heater unit can effectively operate long distances from the termination point.

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

Did you know that you can install an outdoor tankless water heater? This feasibly only makes sense in warmer climates. They're made with components that will protect them from the cold. If your water heater is installed outdoors, there is no need to vent anything. Problem solved!

Use Quality Components

Whatever you choose, be sure to use trusted brands for tankless water heaters, ductwork, and all the other parts and accessories that you may need to make this project happen. We have great deals on Bradford White, Noritz, and Takagi.

Why do you need vents on a tankless water heater?

Vents are required for the proper operation of a gas tankless water heater. It is because it is burning explosive natural gas to heat the water. This, in turn, produces some harmful gases like carbon monoxide as by-products. Without proper venting, these gases will populate the space of your house and can be life-endangering. Hence, extreme caution needs to be taken while installing the vents. Similarly, it would help if you had a certain level of knowledge before you can do so yourself.

How many pipes does a direct vent water heater use?

On the other hand, a direct vent uses two pipes, with one pipe being over the other. The outer pipe brings in fresh air to facilitate combustion while the inner pipe exhaust the by-product gases to the outside. There are two types of direct vent pipes used in a tankless water heater. Knowing which one to use is the most important to get the best results. They are as follow:

How big is a tankless vent collar?

Measure the vent collars on the tankless to know which size of pipes you need. Mostly, it is in size of 3-5 inches, with the inner pipe being a 3-inch and the other one being of 5-inch diameter.

What is a PVC vent?

A PVC Vent (schedule 40) is similar to a concentric vent in that it also uses dual venting pipes. However, unlike an inner stainless steel pipe, both these pipes are made of PVC schedule 40. You can see such a type of venting in a condensing tankless water heater, which is a gas tankless water heater variant.

Why is PVC used instead of stainless steel?

PVC is used instead of stainless steel because a condensing unit even re-uses the exhaust hot gases and vapors to cool the water. This way, the heat of vapors is transmitted to the water, and they become cooler to 40° C. Such cold vapors cannot melt the PVC pipe; hence, you do not need stainless steel to vent them.

What type of pipe is used for a concentric vent?

A concentric vent uses a double vent pipe, with the outer pipe being PVC, and the inner pipe is of Stainless Steel.

What is the purpose of a vent cap?

In the case of vertical or roof vents, set a cap to stop rain and debris from coming into the unit.

How many pipes does a direct vent water heater use?

Direct-vent water heaters can use two separate pipes for intake and exhaust, but some manufacturers offer concentric venting, a single pipe that contains an inner exhaust vent and an outer intake vent. Concentric vents provide a couple of advantages.

How does a power vent work?

Power-vent units use indoor air for combustion and simply vent the exhaust to the outside. Direct-vent units pull in air from the outside, so they have two vents for intake and exhaust. Tankless water heaters’ vents can terminate on a side wall because their combustion fan blows exhaust from the units horizontally.

Why are concentric vents cool?

Second, unlike exhaust vent pipes, which are hot to the touch and thus require clearance to avoid contact with the wall, concentric vents are cool to the touch because they keep the warm exhaust air on the inside.

How big is a concentric vent?

So, while concentric vents are larger — typically 5 inches in diameter vs. 3 inches for a single pipe — they don’t require additional clearance through the wall. Concentric vents also offer a safety benefit, too. If the inner exhaust vent develops a leak, the exhaust air will stay contained within the intake pipe and thus cannot enter the home.

Can a tankless water heater be placed in a box?

6. Placement for tankless water heaters doesn’t always have to be a box stuck to a wall. For new-construction applications, some manufacturers offer recess boxes to keep the tankless water heater inside the wall. At 14 inches wide, noncondensing units can fit between conventional studs; 18-inch-wide condensing units may require more creative framing.

Can you replace a tankless water heater with an outdoor water heater?

Plus, replacing a tank water heater with an outdoor tankless unit can free up indoor floor space. 5. With a condensing tankless water heater, you don’t need metal venting. Noncondensing tankless water heaters typically transfer to the water only about 80% of the heat they generate.

Can a propane tank be vented through the roof?

3. Tankless water heater venting through roof is not necessary. Storage tank propane water heaters vent through the roof using galvanized steel B-vents because they work through natural draft, allowing the hot exhaust air to rise up and out of the facility.

What Are the Venting Requirements for a Tankless Water Heater?

The requirements for venting a tankless water heater depend on the type of venting system you use, which we will discuss in the next section. However, every venting system should ensure the heater acquires enough combustion air.

How many vents does a direct vent water heater have?

A direct vent water heater uses outdoor air for combustion and thus has two vents, one for the air inlet and the second one as an exhaust gas outlet.

Why do you need to vent a gas water heater?

A gas water heater will always require venting to take the corrosive gases out of the home.

What is a concentric vent?

A concentric venting method means that only one penetration is made through the ceiling or wall. However, the holes made for concentric vents are larger since these vents usually have a diameter of five inches compared to the three inches of power venting exhaust pipe.

What is a vent cap?

A small plastic or metal cap as a vent connector between parts inside the house and those outside it

How efficient is an electric water heater?

The lack of venting makes electric water heaters efficient up to 99% since no heat is lost through vented air.

Can a gas tankless water heater be terminated on a side wall?

A gas tankless water heater using a power vent can be terminated on a side wall since the exhaust air is blown horizontally by the combustion fan instead of vertically. The setup here allows for more flexibility in the position of the hot water heater inside the house.

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