In my master bathroom, we have a separate soaking tub and shower. All of a sudden, we can't get hot water in the shower unless we run the hot water in the tub at the same time. If we turn off the hot water in the tub, the hot water in the shower stops too. Any ideas? It happened overnight because yesterday was fine

Thanks
Charlie

You question isn't clear.
we can't get hot water in the shower unless we run the hot water in the tub at the same time. If we turn off the hot water in the tub, the hot water in the shower stops too
I need no know the brand name of the tub/shower valve. What type is it? One handled or three knobs? How old? Let me know, Tom

The shower control is a one-handed dial-type from Sterling. It was installed when the house was built 13 years ago. The tub is a separate soaking tub with sepearate hot and cold, but I don't know the brand and I'm not at home right now.

I should also add that after I posted the message, I did another small test and the hot water will also run in the shower if the hot water is running in the sink which is across the bathroom. Not sure if that helps but figured I'd throw it in

Thanks
Charlie