Varying Temperatures to the extremes of Thermostatic Showers

whatwhat_3

my sister has 2 showers with those Thermostatic shower valves, but for about 2 years now the water never stays at a constant temperature. it goes from extreme hot and slowly goes to extremely cold and back again in intervals. it's so bad that i won't even take a shower when i stay over. but they have to live with that everyday. plus its not safe for my 10yo nephew.
how do i fix this.

(sinks don't have this problem)

keystone

If its only one shower then replace the thermo cartridge.

If it's both it sounds like the installation design or implementation isn't very good if you try and use them both at once.

Does it happen only when both are being used at the same time?

Are they both pumped?

Cheers

whatwhat_3

keystone wrote: »

If its only one shower then replace the thermo cartridge.

If it's both it sounds like the installation design or implementation isn't very good if you try and use them both at once.

Does it happen only when both are being used at the same time?

Are they both pumped?

Cheers

it's either showers, and it doesn't matter if anyone is using the water or not in any other location.

her house was built in 1999. original plumbing. worked fine, then (about 2 years ago) slowly developed this problem. and you would make the change, to the extremes, faster if you try to adjust the temperature manually (and i mean if you try turning the knob the width of a hair, it would go to that extreme of that temperature). one bath is shower\tub and other just a shower. boiler heated water.


the water is pumped from well to a water tank that's pressurized, if that's what you are asking.
how do you change the cartridge?
i installed one of these shower valves in my house and i don't recall seeing any cartridge on it.

i don't know if i have to explain this, i'm sure everyone knows it, but this is the shower that has 1 knob that only turns left and right. left being off, all the way to the right is hot and a little bit to the left of hot is cold.

i hope i explained myself clearly:o.

****edited****
i don't know why that angry icon is up there on the left corner or how to edit it out but i'm not angry
(*ok, i figured it out*)
sorry if i offended anybody

whatwhat_3

andrew-b wrote: »

I would descale the showerhead first in case it's restricting the flow too much leading to the hot/cold cycling. Unscrew the showerhead and see if the same hot/cold cycling occurs to see if my hunch it correct.
More info on the setup needed really.

i cleaned the showerheads. i don't know how to check cycling...


i'm also having keyboard problems, lol. so, by the time it took me to respond to the 1st post i've answered some of your questions you've posted.
thanks