The valve will only push the temp up to about 53 deg, pull the lines off and flush the hoses, check the filter mesh on the unit, it may have crap thats blocking the hotters................................if all that fails, take the stupid thing off and just redo the plumbing but if you are concerned with getting scalded they are available at Bunnings or other hardware joints, just a standard household one will do the job............took the one off in Big M as I got sick and tired of the poor temp for sink and shower, seem to use less water now.