Power Vent Water Heater Venting Requirements

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Direct Vent Water Heater

Venting For Boilers and Water Heaters

When you use a direct vent water heater, the water is heated by the heat generated by the combustion of the fuel. In most cases, a direct vent system results in cheaper water heating expenses than a power vent system since the exhaust gases are vented vertically rather than horizontally, and no additional power is required, as is the case with the power vent water heater.

Gas Water Heater Power Vent / Induced Draft Gas Water Heater Pvc Pipe Exterior Terminations

Again check the manual, but some of the most common water heater power vent PVC pipe requirements are:

  • Horizontal exhaust outlet 12 minimum above the ground or expected snow level
  • Vent riser 24
  • Minimum 18 above the highest point where it penetrates the roof
  • Minimum 6 away from the vertical wall
  • Exhaust pointing down with rodent screen at the end
  • min 36 above the forced air inlet if closer than 120 horizontally to the inlet
  • min 9 -12 from the window / door opening

Below are links to some of the manuals available online showing different types of water heater power vent installations.

Did gas water heater maintenance ever cross your mind? Its very important for your safety and to maximize your appliances performance.

Feel free to ask if you have any questions about the gas water heater power vent system and water heater PVC vent pipe.


Our team of in-house writers led by a retired Illinois home inspector. CTH Expert content attracts 2 thousand readers daily and is dedicated to answering the many questions of home owners and home buyers.

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Gas Fired Water Heater Chimney Codes In The Us

See the National Fuel Gas Code, Chapter 24, Fuel Gas, that includes discussion of venting requirements in Section G2427 p. 360, Venting of Equipment .G2427.3 Design and construction. A venting system shall be designed and constructed so as to develop a positive flow adequate to remove flue or vent gases to the outdoor atmosphere.

G2427.6.5 Gas vent termination. A gas vent shall terminate in accordance with one of the following:

1. Above the roof surface with a listed cap or listed roof assembly. Gas vents 12 inches in size or smaller with listed caps shall be permitted to be terminated in accordance with Figure G2427.6.5, provided that such vents are at least 8 feet from a vertical wall or similar obstruction.

All other gas vents shall terminate not less than 2 feet above the highest point where they pass through the roof and at least 2 feet higher than any portion of a building within 10 feet .

G2427.7.3 Termination. Single-wall metal pipe shall terminate at least 5 feet in vertical height above the highest connected equipment draft hood outlet or flue collar.

Single-wall metal pipe shall extend at least 2 feet above the highest point where it passes through a roof of a building and at least 2 feet higher than any portion of a building within a horizontal distance of 10 feet .

An approved cap or roof assembly shall be attached to the terminus of a single-wall metal pipe.

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Gas Hot Water Heater Venting Problems

One problem you need to avoid is back-drafting. You see this most commonly with atmospheric configurations, and it means that your exhaust isn’t leaving the home. Back-drafting is usually the result of an inadequate vent design. Look for the signs:

  • Corrosion at the top of the water heater
  • Melted plastic at the top, near the draft hood

You can also run a manual test. Isolate the water heater by closing doors and windows, shutting off the furnace, and letting the water heater run solo. If you feel warm air near the draft hood, then your system is back-drafting.

Water Heater Venting Basics

Gas Water Heater Vent Codes &  Standards

All water heater venting systems use a vent duct or pipealso called a chimney or flueto bring exhaust gases from the water heater to the outdoors. The duct may be metal or plastic, depending on the type of vent system. Water heater ducts may lead directly outdoors, or they may tie into a larger vent duct that also serves a gas or propane furnace or boiler in the home. This is called a commonvent configuration. In many cases, the exhaust from the larger appliance heats up the common vent, improving the flow of the water heater vent.

While properly installed common venting systems are completely effective, there is the potential for backdrafting problems if they are not installed correctly. For this reason, common venting configurations are no longer allowed in some code jurisdictions, where direct venting or power venting of water heaters is now mandatory.

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Summary Of Good Venting Practices For Gas Fired Water Heaters

Water heaters must be vented using a listed and approved venting system that provides adequate size, height, and draft.

Otherwise such vents may be unsafe, venting combustion products, including dangerous carbon monoxide, into the building.

Illustrations of proper gas fired water heater venting using Type B- double wall vent pipe through a roof or through a chimney include details for the flue vent connector such as the requirement of a minimum vent connector upwards slope of 1/4″ per foot of horizontal run.

These illustrations are adapted from WHIRLPOOL RESIDENTIAL GAS WATER HEATER MANUAL retrieved 2018/03/05, original source: http://www.whirlpoolwaterheaters.com/media/99595/100263111.pdf

Watch out: regarding these clearances, see the SAFE GAS B-VENT CLEARANCE DISTANCES CLARIFICATION by Charles Buell near the end of this article.

  • Watch out: Carbon Monoxide Hazard. Gas fired water heaters like those illustrated here must be supplied with adequate combustion air and the heater’s exhaust gases must be vented to outdoors. Failure to properly vent a gas-fueled water heater can result in severe injury or death from carbon monoxide poisoning. The vent system must be installed by a qualified person. Examples of a qualified person include gas technicians, authorized gas company personnel, and authorized service technicians.
  • Consult the NATIONAL FUEL GAS CODE, ANSI Z223.1 , a current edition and your local building & fire codes.
  • Inspecting A Water Heater Vent Connector

    Inspecting a natural draft water heater vent happens quickly and easily once you know what to look for. Today, Ill show you what to look for when looking at a water heater vent connector. I recently blogged about inspecting water heaters and testing for proper draft at water heaters, and I just couldnt squeeze the part about inspecting water heater vents into those posts. This is really a topic all on its own, so here goes.

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    Natural Draft Gas Water Heater Vent Pipes Corrosion

    The condition of WH vent pipes should be checked on a regular basis for corrosion and degradation. In most cases, problems with adequate drafting, chimney conditions, and combustion air concerns are the root causes of galvanized pipe corrosion. Small holes begin to emerge on their surface the most prevalent locations are around the bottom section of the product and on connecting points. At some point, the wall of a corroded gas water heater vent pipe becomes exceedingly fragile, and it may even collapse when subjected to even modest pressure.

    Corroded gas water heater vent pipes should be replaced as soon as feasible in order to avoid the potential of exhaust fumes/Carbon Monoxide contaminating the environment.

    How To Compare Power Vent Tank Gas Water Heaters

    How to tell what kind of venting you have on your power vent water heater

    Choosing the right water heater can help you manage energy costs while ensuring an adequate hot water supply for bathing, cooking, laundry and other functions. Thanks to a fan used to expel hot flue gases from the home, you can use power vent tank hot water heaters in applications without the chimney access or vertical venting requirements associated with traditional water heaters. Compare different models and features before you buy to make the most of your investment and find the best water heater for your home.

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    Pvc Vent Pipe Water Heater Power Vent System Based On 2 Pipes

    This system is called direct vent, uses one PVC pipe to supply combustion air from the house exterior and second PVC vent pipe to discharge exhaust gases beyond the house. Both PVC vent pipes MUST terminate on the outside.Advantage of the 2 PVC pipe water heater venting system , is that you can install this type of the water heater power vented system in the closet / behind the solid door, or crawlspace with no vents, etc.

    Water heater power vent systems utilizing double PVC vent pipe also come in high efficiency and condensing high efficiency flavors.

    PVC vent pipe water heater power vent system cannot be connected to the regular chimney or share venting with other appliance

    Types And Sizes Of Pipes That Can Be Used In Water Heater Power Vent Systems

    Typical water heater power vent equipped system utilizes 2, 3 or 4 diameter, schedule 40 PVC, CPVC or ABS pipe. Size of the vent pipe depends on model, BTU rating of your appliance, length of the entire horizontal and vertical pipe section, and the number of installed elbows.

    Example :

    GPVH-40 and GPVH-50 model water heaters.

    Max water heater PVC vent pipe length would be:

    • 40 for 2 pipe
    • 120 for 3 pipe
    • 160 for 4 pipe

    However, for every installed 2& 3 elbow you have to deduct 5 from the maximum distance, and for a 4 elbow 8 of the pipe.

    Always check water heater power vent system PVC vent pipe requirements that apply to your particular model. If you are missing the water heater PVC vent system installation manual, contact the appliances manufacturer / check online if possible.

    • Gas water heater power vent / induced draft gas water heater PVC pipe can be installed vertically and horizontally . For horizontal installations is should be supported every 3 3 ½ to avoid sagging along the run .
    • All connections on the gas water heater power vent system PVC vent pipe must be air tight
    • Slope of the pipe always check manual, but for non-condensing installations level or slightly up-slope towards the exterior should be OK.

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    Gas Water Heater Venting Options

    When installing a gas-fueled water heater in your home, you’re going to think through the project before you tackle it. One primary consideration is, what are your gas water heater venting options? We’ll cover each venting type individually, as well as requirements and some potential water heater venting problems that you may find.

    Venting A Hot Water Heater Through The Wall

    How To Vent A Gas Water Heater
    • When it comes to correctly venting a hot water heater through a wall, it is important to first understand the many types of venting that are available to you to choose from.
    • You can refer to the following list of popular water heaters, which includes information on the sort of venting they require for installation.
    • This page also includes information on installing water heaters in mobile homes, which requires special care in such sensitive settings.

    For more details, see the related article.

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    How To Install Venting Tankless Water Heater Some Important Things To Remember

  • Tankless devices that are installed outdoors allow you to get indoor area. Mounting a heater outside clears up indoor space and does not require extra emission.
  • Condensation units decrease the installation cost. The exhaust vent is made of plastic or PVC pipe instead of metal, which is a feature that lowers installation expenses.
  • Tankless machine venting style offers numerous emission choices. They blow exhaust from the heater horizontally by using fans, thus facilitating vents to end on various positions of your property.
  • Models that have a coaxial vent style provide additional safety benefits. If any pipe begins to leak, the air stays within the coaxial vent and does not enter your residence.
  • Recess boxes support heaters to adjust within walls without suspending the residences exterior. This arrangement allows them to suit inside the houses frame and not hang from the side.
  • Pipe covers and inventive ending points provide attention-grabbing emission solutions.
  • Frequently Asked Questions

    Dont Let These Venting Misconceptions Hold You Back

    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.

    Tankless water heaters vents can terminate on a side wall because their combustion fan blows exhaust from the units horizontally. This fact is particularly helpful for professionals replacing electric tanks which dont require venting with propane tankless units.

    While commercial and large residential applications may use multiple tankless units, they dont necessarily require two vent penetrations per unit.

    For many customers and projects, selecting a propane tankless water heater is a smart decision.

    Propane tankless water heaters are one of the most efficient water heating options available, providing a reduction in energy costs of up to 50%. In addition, these systems can reduce greenhouse gas emissions by up to 61%.

    But in some cases, misconceptions about the venting needs of gas tankless units might keep professionals from recommending them. If venting concerns are keeping you from installing tankless water heaters on your projects, these tips might help you find a simpler, less expensive solution.

    For more information on tankless water heaters, visit Propane.com/Water-Heating.

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    How To Vent A Gas Water Heater

    • Similarly to a furnace, water heaters with gas burners will emit toxic gases including carbon monoxide, which is a result of the fuel used to light the burner in order to heat the water in the tank, regardless of whether the fuel is natural gas, liquid petroleum gas, or propane.
    • In the same way that you need good venting for your furnace, you need adequate venting for your water heater in order to exhaust the harmful gases to the outside of your home in order to keep you and your family safe.

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    Power Vent Water Heater With New PVC Venting In Rosemount And Water Softener

    Continuing: from the IO manual we have

    Venting System Condensation

    Condensate formation does not occur in all installations of power vented water heaters but should be protected against on installations where condensation can form in the venting system

    Formation of condensation in the venting system of power vented water heaters is dependent upon installation conditions including, but not limited to:

    • ambient temperature and humidity of installation location
    • ambient temperature and humidity of venting space
    • vent distance and slope
    • and product usage.

    In order to effectively control condensate from adversely affecting the mechanical components of the water heater several methods may be employed:

    1. For horizontal installations the vent pipe can be installed with a downward slope ) and away from the blower.

    2. In order to prevent condensate from draining back into the blower , an optional condensate kit is available as a service part .

    A molded exhaust adapter with drain outlet is secured with one hose clamp, to the vent pipe.

    Tubing is provided to drain any accumulated condensate away from the water heater and to a suitable drain.

    The kit comes complete with instructions for proper installation.

    But an experienced technician could certainly make a visual inspection of your water heater and could express an opinion about the nature, location, and specific components affected by any corrosion she can find.

    On 2021-11-18 by William in Missouri

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    Natural Draft Gas Water Heater Vent Pipe Pitch

    Sheet metal screws should be used to fasten the connection between the draft hood and the vent pipe three screws per connection on a single wall pipe is suggested. When securing or sealing connections, do not use conventional duct tape. Aluminized tape is not permitted on joints by some building inspectors. Why? Simply because rust or holes growing on the surface are concealed by this material. If you are using a B-vent, which is a double-walled vent pipe, you should only use screws on the first connection either to the draft hood or to the single-walled water heater vent pipe since the second connection will be weakened by the screws.

    Whats The Difference Between Atmospheric Vent And Power Vent

    Most people dont know a lot about water heaters. You may simply know that when they work, your shower is hot, and when they dont, they let you know quickly with a blast of cold water.

    Two of the most common type of water heaters are atmospheric vent water heaters and power vent water heaters. While atmospheric vent water heaters are simple and dont require electric power or moving parts, power vent water heaters use a fan to push the excess gases through the venting pipes and outside. Continue reading to learn more.

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    Differences Between Direct Vent And Power Vent Water Heaters

    • We at Haley Mechanical recognize that, given the plethora of names that are used to describe water heaters, selecting the most appropriate one may be challenging.
    • There are several varieties, and deciding which is the most appropriate for your scenario might seem like an intimidating undertaking at first.
    • Direct vent and power vent water heaters are two of the most common types of water heaters on the market today.

    A power vent water heater removes combustion gases from the environment by the use of a powered venting fan, whereas a direct vent water heater vents combustion gases into the external atmosphere through the use of a chimney or exhaust pipe.

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