I have a single handle lever Kohler shower valve. Everything had been working fine for the past years, but suddenly within the last week or so, I am faced with this situation:
The way I've known it to be until recently, the shower is off at the 9 o'clock position, and is at max hot at the 3 o'clock. I used to find my sweet spot at around 1/1:30.
Recently, as I try to nudge it ever so slightly around the 1/1:30 position to get it 'just right' at the beginning of my shower, it will suddenly go scalding hot on me. Scalding, steaming, hot. If I move it back, even to around the 10:30 position, it may stay scalding for about 30s, then gradually get colder again to what I expect it to be at that position.
It seems moving it back from the 1:30 to the 10:30 position tends to make it cool down VERY slowly (30s), but if I flip the lever to the off position (9 o'clock) and switch it back to the point about where it was scalding (back to around 1:30), even with a quick swift movement that takes one second to complete, it is immediately comfortably warm/hot (where I expect it to be at 1:30), and may stay comfortable at that point -- but within 10-30s get scalding hot again.
As an experiment, I set my bathroom faucet to be a comfortable warm/hot, and let it run while I was taking a shower. I wanted to see how the water from the faucet behaved versus my shower's. When the water is scalding from the shower at the 1:30 position, the bathroom faucet stayed at the same comfortable temp I had set it at earlier.
We do not experience this issue in any other faucets or showers in the house.
Before I called a plumber, I wanted to get ideas from this forum on what it may be, especially if it may be symptomatic of something simple like replacing a washer or the cartridge.
Many thanks in advance.