I've installed a Kohler Thermostatic Mixing Valve with Volume Control (K-404) in my shower construction project and just noticed that the hot water is circulating up through the valve and then back down the cold pipe! Yikes- this puts water from the hot water heater into the drinking water and seems like a big energy waster. I'm sure the valve is installed according to their directions and nothing is leaking. Reading further about how the mixer works, I can imagine how this happens. Seems to me that they should warn you about this.

Is there anything practical I can do? What about a backflow valve on the cold water supply to the shower? Would it cut down on the flow? Putting one in at this point when most everything is covered would be a real pain, but is probably better than leaving the situation as is.

Tom - Have you ever seen anything like this? Would the backflow device work? Thanks - Dennis

No I haven't Dennis, This is a cross connection but I can't pull up a breakdown view of the faucet but if I were him I'd return the valve and ask for a replacment. Regards, tom