HuntingtonBrass PL8950 Thermo valve -hot or cold only

installed this valve, PL8950, exactly to instructions...installed trim parts, handle etc, let 'er rip, and two problems: most annoying one is that i either get all hot, OR all cold, not a selectable mix of the two. possibly related is the red safety button locks out from the temp numbers on the small trim ring getting lower.. i.e., it's as if the safety is to prevent you from making the water any colder.. obviously, that is not the point, and clearly something is 'running' in reverse..

problem 1) when rotating the temp valve handle from max left to max right, at about the 8 0'clock position, there's a barely noticeable flicker in the stream from the showerhead as it switches from all hot to all cold

problem 2) rotating the handle counter-clockwise, the stop button 'locks' the valve from being turned further counterclockwise, which is in the direction that brings in all cold water...turning the valve clockwise, i.e., placing the handle towards the max 9 o'clock position, corresponds to LOWER temp numbers on the small dial/trim ring as i turn it to all HOT water....?!?!

any help from the pros? i've installed this for my girl's brother, he bought it as a closeout display model with no instructions, i've been using the pdf files off the mfg website.. i've talked to HB awhile ago, and they told me basically if there's a cartridge problem, i'm screwed, because while they normally send out replacement parts, this one is their high end 450 buck cartridge, they won't...

the 'backwards' temp conrol, i can deal with.. i'm sure i have some cam reversed, etc... but i should be able to rotate a valve and decide how much of each temp of water i get, right??!?!

temp

IF the cartridge or valve in installed backwards, you are confusing the valve's brain. When you turn it to "hot" that side is cold but in order to get the set temperature the valve is trying to add hot water. Since your valve seems to have the cold water connected to the hot side, and vice versa, the farther the "hot side" opens to make the temperture hotter, the more cold water you get, so the valve is like a dog chasing its tail. The same thing happens when you go to the cold side. The valve opens the cold further and further as the temperature rises, but it is rising because there is more and more hot water coming in. Reverse the cartridge, if possible, and everything should work properly. If it cannot be reversed, then the manufacturer may make a "reversed" cartridge to handle backwards piping. If neither of these are possible, you will have to repipe the valve properly.

In a 'normal' valve, the hot supply will be on the left as you look at the trim side of the valve. Often, there will be some marking on the valve to indicate hot and cold.

valve

A "normal" thermostatic valve will ALWAYS assume the hot is on the left, (unless it has been modified for reverse installation). If it is then connected backwards, THAT is what will confuse it and your water temperature.