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.