Ever since we purchased our MH we've had issues with the hot water tank mixer valve. First year we owned ours this valve was replaced as it was noisy. In less than 3 years it needs replacing again. ...
Mine was at the water heater. It stopped up. So I took it out, and replumbed the entire water system around it. Now, it's just like any residential (older) water system.
I'm a licensed plumber, not that it really means anything. BUT, I had all the tools (crimpers), and fittings to do the job.