The palmer valve is a check valve of sorts it is suposto allow water to go down the drain but closes when there is a back up. most of the ones in colorado do not work any more and need to be removed or replaced
David,
Let me try.
A clad window, many windows in my area are wood on the inside and vinyl or aluminum on the out side. This is installed during the manufacture of the window. So you end up with a Vinyl or aluminum clad window.
As far as the palmer valve Henry explained it but I’ve never seen one. Either they are not in the drain or they are beyond sight.
The word “clad” means clothed or covered. Generally it refers to wood framed windows that are “clad” with another material, such as vinyl or aluminum. Just like Bill said. Only he said it sooner.