Whenever the washing machine is turned on and the warm water is selected, somehow the cold water sems to be forced back into the hot water line causing the other hot water faucets in the house to run cold water. This does not happen if either the hot water or the cold water temperature is selected on the washing machine. It should be noted that the cold water line to the washing machine is the first tap into the cold water line from outside and the hot water line to the washing machine is the last tap coming from the hot water heater. It should be, further, noted that the pressure regulator for the house water is installed after the tap for the cold water line going to the washing machine.

 

Pressure regulator at wahser machine, this makes no since to me. most regulator are on the water service just infront of a water meter. You might ask Jeff at the appliance forum, and see if the washers have a check valve in there that is suppose to prevent mixing of water back to the faucet in the house, other then that I have no clue.