Black tank flush valve

[VinceU]

Originally Posted by john mcneely

Forester Fred you misunderstood. My intention was not to flush black tank. I mistakenly hooked to wrong inlet. My intent was hooking up fresh water.

Could be the overflow caused the back flow piston to jam in the safe/ off position. The valve is well pictured in this this thread, remove, open and free up.

[Mr. Dan]

Originally Posted by john mcneely

What is a B&B made valve and where is it?

It's not good practice when talking about RVs to say your _______ is located here or there because it seems no two are necessarily built the same.

That said, I've seen these black tank flush vacuum breaker/anti-reversing valves located in the bathroom sink cabinet and ...
I've heard them located in the wall behind the shower enclosure (that's where mine is).