The mechanical float valve that EVAPCO uses operates with a makeup water pressure between 20 and 50 psi.  When the makeup water pressure exceeds the 50-psi limit, the makeup valve will not close.  The reason for this is that the buoyant force of...

If the unit was just installed, the rust is probably not affecting the integrity, or life expectancy, of the base stainless steel material.  It is most likely foreign material on the surface that can be cleaned. 

So, where is the rust coming from?  The rust spots that show up on the surface of the unit are...