i have an older double wide mobile home that i turned into a quad wide. the water comes out of the ground at the front of the trailer and the inlet to the house waqs 30 feet to the back and then the old hot water heater was 10 feet from the front so the3 old electric water heater went out and i had already purchased a new propane tankless water heater. when i started the instalation i moved the inlet to the front by where the water comes out of the ground so i only have 10 feet of water line that has to be insulated and where the main line comes in i have a t one side goes to the cold water for the house the other side goes directly to the water heater less than 10 feet goes through the water heater and back to feed the hot water for the house. everything works right accept the main shower wich is right next to the t , when you turn the hot water in the shower on it gets hot like it should but as soon as you turn the cold water in the shower on the water heater shuts off having trouble figuring it out. the main line from the ground is 1 inch in the house it t's off to 3/4in to the cold side and 3/4in to feed the hot side but the inlet and outlet on the tankless waterheater are 1/2in what do i need to change