Chinook RV

Okay, so I need to do some plumbing repairs. For the first time since I've had the rig, I wanted to completely empty the fresh water system. I found the drain valves at the front of the coach thanks to the manual, but when I went to look for the water tank drain petcock, I found... this.
I confess I haven't spent much time laying on the floor studying the plumbing before today, or I might have noticed how odd that was earlier.

It looks like they used a couple of pieces of hose to insert a quarter-turn valve between the water pump and the water tank, and connected a length of open-ended hose in there as well.

All I can imagine is that they were using this to pump anti-freeze through the supply lines from a bucket or jug. Does that seem reasonable?

My favorite part is that, to keep everything in position and make it easier to turn the valve with one hand, they added a block of wood, screwed into the floor, and a stiff plastic card, to prevent the valve moving while you turn the handle.

All I can imagine is that they were using this to pump anti-freeze through the supply lines from a bucket or jug. Does that seem reasonable?

Yes, this seems very reasonable…We had something like this on our fifth wheel camper we had. I think they called it a “hot water bypass kit”?… I cannot tell from the pictures if you have a “bypass kit” installed or not. But the open end tube is definitely used to winterize the camper. The hot water bypass kit was used to bypass the hot water heater so that you do not pump 5 gallons of antifreeze into the hot water heater when winterizing.