[Seaduction]

The problem I have with that check valve is in draining the hot water heater for winter storage. I was hesitate about removing that fitting thinking that I might damage the heater tank so normally I just apply air pressure and try to blow out as much water from the tank through the faucet and then add the good old pink stuff.

There should be a pressure relief valve that you could open for allowing air in to facilitate draining.

 

[Seaduction]

If I remember right that check valve is located right at the tank so putting in a bypass T to drain the tank is not practical, not to mention that the location of the tank makes working on it difficult. The use of the relief valve to drain the tank might be workable, but I think I tried that in the past and was not successful.

Not suggesting to drain thru the relief valve, but to open it to allow air in so the regular drain can function.