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DFU stands for drainage fixture unit. This is a measure of probable fluid discharge into the drainage system by various types of plumbing fixtures. Each fixture’s DFU value depends on the volume of fluid discharge per cycle and an average time between cycles. The chart below gives you some examples of fixture DFU calculations. Always check with local building officials to confirm these calculations match theirs.                                                                                

  • Private Toilets (1.6 gpf) – 3 DFUs
  • Public Toilets (1.6 gpf) – 4 DFUs
  • Urinals (1 gpf or less) – 2 DFUs
  • Shower (5.7 gpm or less) – 2 DFUs
  • Kitchen Sink (domestic) with food grinder and / or dishwasher – 2 DFUs
  • Laundry Sinks (1 or 2 compartments) – 2 DFUs
  • Bathtub with or without overhead shower or whirlpool attachments – 2 DFUs
  • Residential washing machine – 2 DFUs
  • Commercial washing machines – 3 DFUs
  • Bathroom Group 5 DFUs - consisting of 1-toilet (1.6 gpf), 1-lavatory sink, 1-bathtub or shower, including or excluding 1-bidet and 1-emergency floor drain. All fixtures in this group must be located on the same level. 

Sure-Vents come in 6 DFU capacity, 20 DFU capacity, 160 DFU capacity and 500DFU capacity.

A minimum of four inches above the horizontal branch drain (trap). 

No. The AAV must have access to the open atmosphere. If the Sur-Vent is to be installed in a wall cavity, you must use one of our AAV wall boxes with a louvered face plate. This allows the Sure-Vent to have access to the open atmosphere, and also acts as an access door.

Yes, with exceptions. The attic has certain conditions that can affect the AAV performance which should be considered before choosing this as a location. The temperature ranges that the Sure-Vent will operate in are -40°F to 150°F, your attic can experience drastic temperature variations depending on how it is vented and your geographic location. Insulation fibers can get caught inside the diaphragm which will make it harder for the diaphragm to open, or achieve a good seal when it is in the closed position. The Sure-Vent should be installed a minimum of six inches above the finished height of your insulation, and the attic must have an access point to conduct scheduled maintenance.

Yes, with exceptions. Always check with your local building officials to confirm this application is approved in your municipality before attempting this installation. We also recommend that you check with the pump manufacture before completing this installation. Remember that you also need to vent any fixture or group of fixtures, check with your local building official to ensure your plumbing system is designed properly before installation. If they are not vented properly the drains will not flow properly. After confirming all parties involved approve this application, you can contact our customer service department and they will be happy to send out a drawing explaining the application. 

Yes. The Sure-Vent is a mechanical device and like all mechanical devices, a scheduled maintenance routine should be set up to ensure AAV is functioning properly. 

No. Every dwelling needs to have one main vent stack exiting the roofline into the free atmosphere. It is also recommended that a relief vent be installed when completing a new home or large addition rough-in. 

No. The Sure-Vents are not designed for exposure to Ultra Violet Rays.

AAV = Air Admittance Valve. 

DWV is an acronym used in the plumbing industry which means Drainage, Waste and Vents.

No. You should however bevel (chamfer) the pipe end to prevent cutting or scaring of the rain collar as it is being pushed over the pipe.  


TPE, Thermoplastic Elastomer 

Yes. The Oatey High-Rise Thermoplastic All-Flash No-Caulk Flashing is designed for roof up to a 60° angle (20/12 roof). 

No. The Master Flash and Retro-Master Flash are specialty flashings designed for engineered roofs.

No. The Oatey Master Flash or Retro-Master Flash should be used in this application.

This question doesn’t have a correct answer because of many variables that could affect the life span of a flashing. Examples are extreme heat, extreme cold, and hail.

Oatey Master Flash and Retro-Master Flash are rated for continuous temperatures up to 212°F. All other Oatey flashings are rated for B venting, which are continuous temperatures up to 180°F.

100% exterior or marine rated silicone caulk can be used to seal plastic base flashings to the rooftop.

Single wall metal exhaust pipe should never be used to vent a water heater or furnace when the pipe passes through a combustible material of any kind due to risk of fire. The flashing rain collar will melt or warp if exposed to these temperatures passing through the single wall pipe, and loose the water tight seal it is designed for. All water heaters and furnaces not listed as high efficient should be vented using rated B vent pipe. B vent pipe is doubled wall pipe which isolates most of the exhaust heat to the interior pipe. All Oatey flashings are safe to use with B rated vent piping.

With the exception of the Master Flash and Retro-Master Flash, all flashings have a one year warranty from the date of manufacture. Flashings cannot be guaranteed for the life of the roof due to varying roof life spans, and potential adverse conditions (i.e. extreme heat, extreme cold, hail). If a roof is replaced the flashing should be replaced at the same time. Master Flash and Retro-Master Flash are the only exceptions; if installed properly according   to industry standards, they have a 20 year warranty from date of manufacture.

Yes. The Oatey Master Flash and Retro-Master Flash are designed to conform to most roof profiles.  

After the correctly sized collar has been selected; you will apply a 100% exterior or marine rated silicone caulk to the top of the existing rain collar attached to the roof flashing, and also to the underside of the new rain collar. Slide the new rain collar down over the pipe to the top of the existing collar. Press the new collar down with enough pressure to seal the two together without collapsing the seal around the pipe.

The size of the flashing is determined by the OD (outside diameter) of the pipe penetrating the roof or sidewall of home or building. Never try to slide a smaller flashing collar over a larger pipe because it will cause fatigue failure in the collar. Never install a larger collar over a smaller pipe and try to use sealant to fill the void. Any sizing miscalculations will lead to leaks within the home or building.

Oatey is pleased to announce that we do offer such a valve for washing machine and ice maker connections; it is called the “Push Connect Valve”. These valves come as part of our Outlet Box collection. They are designed to easily accept ½” Copper, CPVC and PEX pipes, by simply pushing the ½” pipe into the Push Connect Valve Fitting. If for any reason the pipe needs to be removed after installation, no problem. Simply use the quick release tool to remove that section of pipe, and insert the new piece of pipe. No need for solder, pipe joint compounds or thread sealant/Tapes; just cut, de-burr and chamfer (bevel) pipe end before pushing and connecting the pipe.

Hammer arrestors are designed to help with water hammer (banging noises) in the water lines when a washer or ice maker are in use. When the appliance’s quick closing valve shuts off, it will exposes any loose piping in the water supply system and make banging sounds. The hammer arrestor helps absorb the shock and minimize or eliminate the banging sound. Oatey manufactures a full line of pipe supports which can assist in securing the loose pipes.

Yes. Oatey offers a #38494 WMOB and #38495 IMOB that have a Warnock Hersey Certification for 1 and 2 hour fire rated walls.


No. Washing machine valves are not considered a source from which potable (drinking) water is gathered, and are not required to meet lead free requirements.

Yes. All Oatey ice maker valves are lead free and meet NSF 61, section 9 requirements.