I have a Delta single-handle shower faucet handle, the kind that you push upward to turn the water on & turn right for cold & left for hot water. I am able to get very warm water only if I allow about 1/3 of the normal amount of water to come out. However, when I turn the water on at full blast when the handle is turned to the hottest setting, suddenly the water that was very warm (when I had allowed 1/3 of normal water to flow) now turns cold. Basically, I cannot get hot or even very warm water when the handle is pushed up as far as it will go to allow a full stream of water, instead I get cold water.
Can anyone help explain what the problem is and how to fix it. I have no trouble with getting hot water in the bathroom sink, which has a single-handle Delta faucet.