I am currently redoing the shower/tub surround, and would like to know what valve I currently have. It is a Moen, and uses the 1225 cartridge (crystal pull out handle, pull for volume twist for temperature). On the side, it looks like "85811". The house was built in 2000. High-end materials were not used.
I ask about the current valve, because we are having a terrible time with controlling temperature. Even turning on the sink (hot or cold) will affect the shower temp, and things like dishwasher and clothes washer make the shower useless with all the temperature changes. But from what I understand, this valve is some sort of mixing valve that should be handling temperature fluctuations like this. If this valve does this, then would a fancy thermostatic valve accomplish anything? Or is there some other cause.