The best installation location for Sanitary Check Valve is at the exhaust fan outlet or the main entrance of the flue.

‌Exhaust fan outlet: This is the most common installation location, because the main function of the check valve is to prevent odor and mist from flowing back into the room through the exhaust hole. Installing it at the exhaust fan outlet can ensure that the check valve effectively plays a barrier role and prevents odor and backflow.
‌Total flue entrance: For bathrooms without exhaust fans or bathrooms with more complex exhaust systems, the check valve can also be installed at the main entrance of the flue. This ensures that the exhaust system of the entire bathroom can be protected to prevent odor and oil smoke from flowing back into the room.

When installing, pay attention to the following points:

‌Installation time: It is best to install the check valve after the tile seam is completed and at the latest before the ceiling is suspended. This ensures a smooth installation process and is more convenient for later maintenance and replacement.
‌Adjustment of installation position‌: If the hole provided by the developer is at a lower position, for the sake of beauty and smooth concealment of the smoke exhaust pipe, you can ask the tiler to re-drill a hole at the top of the flue when tiling and plug the original hole‌.
‌Installation tips‌: The check valve should be installed on the tile. Ask the tiler to stick the wall tile where the check valve is installed to the top and drill a hole according to the size of the check valve. After installation, a circle of sealant should be applied around to ensure sealing‌.

In short, the best installation position of the bathroom check valve needs to be determined according to the actual situation, but no matter which position is chosen, it is necessary to ensure that the check valve can play a normal barrier role to prevent odor and backflow.