It is not RV-related, but winterizing is what most of us do, so I hope-(knowing lot of smart people posting here) to get some answers.
Bought a house in Las Vegas that was build by AA pilot (poor guy died few years ago).
House is very sophisticated and when figuring out 40 audio controls was easy, I still have few of 120 light switches to label.
What was mysterious for some time are 2 valves on the wall in master bathroom.
I had water on and off due some other plumbing problems, but finally had a chance to see what they do.
So in master shower ceiling I have 1" pipe sticking down. When I open each valve (who are on other side of the wall) I have water coming down from the ceiling pipe into shower.
Looks to me like winterizing valve, but I frequent Vegas for last 30 years and so far have seen snow here only once-lasting about 6 hr
Any explanation what da hack it was build for?