I have an On Demand Hot water tank, and love it. My Issue is I am using a manifold to distrubit both the hot water and cold water, through a pex system. I'm having issues with the hotwater pressure. The unit I've installed is designed for multi uses at one two to three appliances at once. When runing any hotwater sourse and you turn on the second, the pressure immdeiatly drops by 1/2. I have the heating unit set to 115 degrees f. I have a 1 supply line runing from the heater to the manifold. and all lines out of the manifold are 1/2" pex. I have no issues with the cold water pressure out of the manifold. Any one have any ideas.