Shower problem

[Linflas]

Our main shower has rather suddenly started having temperature control issues. The best way I can describe it is the temperature oscillates around a mean while taking a shower. Once adjusted to the desired temperature it will proceed to get hotter then back to desired then cooler then back to desired then hotter repeat endlessly. The shower control is a single knob Price-Pfister and we have a standard gas water heater. Given that our house is 19 years old I know the water heater is on borrowed time but I don't see how a water heater going bad could cause this. Any ideas what I should be looking for?

 

[richardycc]

it's most likely the shower mixer value has gunk in it. clean or replace it should fix this problem.

 

[jaha2000]

You need to replace the cartridge on the inside.
The next thing it will start to do is not get hot, something in the anti scald feature is starting to fail.
http://www.pricepfisterparts.net/st...91-0364-lasco-0-2089-shower-pressure-balance/

mine looked something like that in my Pfister single handle

 

[Linflas]

I had it apart once before about 4 years ago for another issue and had a heck of a time finding the parts diagram/model # info for it at that time. I guess I will turn off the water and take it apart again and see if I can clean it enough to see if that fixes it. We plan on redoing this bathroom in the next 6 months and replacing the Price Pfister fittings with something new so hopefully just a cleaning will fix this if that is what is causing it.