New shower fixture is only allowing either hot or cold water and not a blend of both

the_new_guy

I recently installed a new shower fixture and for some reason, the thermo valve is only letting Cold, or Hot water and not a blend of both of them. As I turn the thermo valve I can feel a sudden change of pressure from Cold to Hot, or Hot to Cold when turned the other way.

I've tried replacing the cartridge twice, as this type of issue is usually because of a defective cartridge. However, that did not help at all.

I only have this issue with the new shower fixture and not with other showers in the house, or even the previous shower fixture that was replaced.

Because the thermo valve is only letting Hot water in, the water gets too hot; and when thermo valve lets cold water out, it eventually gets too cold to tolerate.

I purchased the shower fixture from Bath Depot. The model is KEBO S8T-3883CH.

link: https://www.bathdepot.ca/en/chrome-square-thermostatic-shower-faucet-with-rain-showerhead-s8t-3883ch.html

Any help or suggestion is much appreciated!

Ryan

Intplm.

Hello Ryan
@the_new_guy
You are correct when saying this is a defective cartridge. Replacing it should have corrected the problem. I often call this a ghosting or hunting problem when the thermostatic cartridge is defective and tries to, but cannot find a steady temperature but hunts for a temp.
The hard part about this is that there might be a washer or gasket doubled up from the factory and or from your repairs that you are not aware of.

hot_rod

is the pressure the same  on hot and cold? A wide pressure difference can cause thermostatic valves to hunt

Temperature on the hot needs to be about 20 degrees hotter than mix for stable operation on thermostatic valves

Usually they fail to cold however, under those conditions 

Intplm.

@the_new_guy .

@hot_rod makes a very good point here. These cartridges are commonly described as pressure-balanced.
They are designed to stop the old joke of flushing the toilet while someone is taking a shower and having the water suddenly go cold, or was it hot? Remember that old prank?

It is a safety precaution

So the pressure needs to be in line with the specs of the valve.
Look into the above thoughts. Hopefully, you can find a solution.

dwhipps

I have this exact same problem, with the exact same model. I replaced all three cartriges and the problem got worse! The water shuts off completely when turning from cold to warm/hot. What's the resolution here?