4" Backflow and F-F Adapter

This is installed in the exhaust line to prevent fumes from back-flow. We did not need the 3" to 4" adapters for the 3" PVC as this fit perfectly on the OD of the PVC.

This piece works fine. It took me forever to figure out what Z-Vent to order to vent a Takagi water heater in my unfinished basement through the sill plate and of course I didn't get it right and will need to order two additional 12" long vent pipe pieces. The information on the Z-Vent website and here is not sufficient to design your solution. Unless you are mounting the Takagi on an above grade wall 6" thick or less, you will need additional vent pipe; about 18" vertically and 5" horizontally. The total clearance using this F-F damper, an elbow and the vent hood is 8.625" vertically and 6" horizontally. The missing design information: this piece is 5.875" long. Inserting the male into the female uses 1.5". The elbow is 8.5" vertically and 8.25 horizontally. The flange on the Takagi is 2.25" and is 2.5" from the backplane of the unit. The pipe on the back of the vent hood is 5.75" long. The SupplyHouse website does not show the required vent pipe pieces where they would be expected to be but they are available from them. Venting the water heater requires cutting a 6" diameter hole through the wall or joist and you should make the run as short as possible. The total cost of a basic solution is $180 with Supply House's pricing. The this connector and the elbow are individually boxed. I probably should have called and had them explain what to order. I don't understand why Z-Vent doesn't publish complete design data or installation advice.