First time seeing one of these drain seals. I am providing a link to similar product.
Is there a notable downside to one of these seals? It claims to help prevent sewer gases from escaping. Which make sense since this trap will likely dry out. And trap primers seam to be out of fashion.
I’ve never seen one in use, so…
As the seal is made of rubber, it should not impede or be considered a reduction in the WH drain size.
As to it’s use for a drain that will hopefully never see use from the TPRV discharging, and only from insects, rodents, etc. from the exterior, as a precaution I would fill the trap with an RV Antifreeze to minimize evaporation and act as an insecticide to prevent nests from being built in the trap. This should be maintained on an annual or bi-annual basis depending on the trap diameter installed and local climate temperatures.
So the p-trap is 100% designed to seal off sewer gases(when filled with liquid). I get what they are trying to do (Because in a perfect world this drain will not be used)my concern (that you cannot put on the report) is that if the device either restricts the flow once the T&P valve is opened or the device sticks shut blocking the flow.
Oaty is a good company with good products but anything just put in the air break scares me. One of the things you might note is the lack of vertical support in those T&P valve drains.(where they go down to the air break). If you open one of those valves , that pipe will most likely jump right out of the drain. So, vertical support on the wall needed to make drains more ridged and prevent unintentional overflow or spillage onto the surrounding floor if the valve/s open up.
The other thing is that it IS an “Air Break” , it should be an “Air Gap” wich means it should flow through free atmosphere before entering the drain. So, the bottom of the blow off tube/pipe would be a few inches above the drain.
Sorry so lengthy but it is what it is.