I have a 235 and I want to run my heater hose to the cab. I thought that the lower hose fitting at the pump would be sending the water to the heater and back to the top hose fitting. In doing so it seems to be backwards. Does the water push out the top fitting and back into the bottom hose which is at the pump. I want to have my shut off before the heater and I have it on the bottom hose connection which seems to be on the return. Thanks