I recently moved into a new (to me) house in Reno. It’s appointed very nicely, high quality fixtures, great construction throughout. But several of the sinks exhibit very weird and inexplicable behavior when attempting to adjust the hot & cold water temp. I’ll start the hot water running with the left knob, it of course starts out very cold, and wait (a long time, but that’s understandable, it’s quite far from the water heater) until the water gets suitably hot. Then, I’ll try mixing in some cold from the right knob, and the water stays hot — really hot. In fact if I turn the hot completely off, the “cold” water stays just as hot... for a LONG time. Nearly as long as I had to wait for the hot to begin with. WTH? It seems like the longer I let the hot run, the more it negates my ability to get cold water. If I just run hot for a few seconds, then the cold water responds much faster. Looking under the sink, I see a suspicious gadget with the incoming hot/cold water lines attached (the big hoses), along with two outgoing lines feeding the sink’s hot/cold valves (smaller hoses). I’m guessing this mysterious widget is the culprit. What the heck is it? Is it broken, or is its purpose in life to prevent me from ever getting the water temp I want?