Recently a contractor, who is remodeling our bathroom, installed a new American Standard valve in the bathtub, but has not yet hooked it up to the filler spout. He shut off the water at the main for about an hour until he completed the installation. Ever since we have had hot water coming out of cold and vice versa throughout the house. After any of the faucets run for a minute they seem to right themselves, yet the only way to get really hot water from the showers is to run hot water in the sink in the same bathroom. Is there a simple fix for this? I tried turning on every faucet in the house to hot only at the same time, but that did not work.