Crossover between hot and cold

I'm a maintenance wholesaler and I run into crossover between hot and cold lines with single handle faucets. It is difficult to convince an apartment owner or hotel owner of this problem. Do you have any articles about this problem?

The most well known problem was with Mixet valves. They were famous for this, and the problem was with wear on the body. Replacing the cartridge did not always fix it. There is a company who developed and sells a replacement aftermarket "no-crossover" cartridge for Mixet, so this suggests the magnitude of the problem.

I have heard tell that Moen can crossover, and of course theoretically they can, but I don't think I remember seeing it.

One thing which is instant crossover is if you put a "pause control" or shut off button on the shower arm. When you shut off the head but leave the main valve on, crossover happens instantly!

crossover

I run into "bad" Moen cartridges that are "crossing over" all the time. One way to find them is to turn off the water heater supply then open a sink's hot water faucet. If water still flows you have crosssover. Then go to each Moen, Mixet, Grohe, etc., and turn it to the full hot side. Unless there is more than one bad one, when you turn the bad one, the water flow will stop. You can also sometimes hear the water crossing over inside the valve if it is bad enough. One thing to remember, is that the bad cartridge may not be, and often is not, in the apartment having the problem.

when crossover happenswhat are the results,other than

tepid water ect. thank's tool