Hi, we had a hot water circulation system put in 17 years ago to continuously take hot water to the two ends of the house.

About 6 months ago we started to have a problem where the cold lines would have hot water in them if no water had been used for several hours, e.g. overnight. At the same time we started to have issues with getting water hot enough for showers in our primary bath.

I suspected that the backflow of hot into cold lines is happening in the primary bath, i.e. that the Kohler shower faucet that can't get the water hot enough is where the backflow happens.

I unplugged the circulator and shut off the flow in the circulation (i.e. secondary) pipe coming out of the circulator. When I turned that Kohler shower on full hot the water quickly transitioned to fully cold, i.e. same temp as straight cold water. All other hot water outlets and other 1 handle showers and faucets are now fine, i.e. no backflow into the cold lines anymore.

I saw another note here suggesting shutting off the hot water and opening a hot water tap - the hot water shouldn't flow or should stop flowing pretty quickly. When I did that it flowed full force for maybe 10 seconds then gradually slowed to a trickle, but the trickle does not stop - remains steady.

My working theory is that the backflow is happening in the Kohler 1 handle shower valve in the primary bath, that when we were using the circulator that would make the pressure higher in the hot versus cold lines, forcing hot into cold at that valve, and that the trick of shutting off the hot at the tank resulted in the continuous trickle because doing that resulted in cold backflow into the hot lines at the same Kohler valve.

That shower now running continuously cold when set to full hot is what has me completely stumped. It's as if turning the circulator off and closing the circulator line that creates the loop is now preventing that shower valve from getting any hot water at all. The 2 nearby sinks that also benefited from the circulator loop have no issues at all - steaming hot water readily available.

Any advice is greatly appreciated! I have a plumber coming to replace the Kohler cartridge and mixer this coming Monday based on where I'm at so far.

Thanks!

the pressure balancing valve inside the shower is 'stuck'


time for a 'shower valve rebuild'

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

OK I'm not schooled in any of this - I take it that's not going to be fixed by simply putting in a new cartridge and mixer(?)

Thanks!

the shower HAS a cartridge

it also may, or may not, have a pressure balancing 'spool' (similar to a cartridge)

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

i have seen this issue before.

it's been a long time so i don't remember part numbers.

call 1 800 4KOHLER for tech advice