yes, if you're not running a heater the pipe from the manifold will go back to the water pump.
once it returns there it mixes with the remainder (majority) of the coolant to be pumped through the rad then back into the bottom of the engine.
so if your pump works there is a continuous process where cool coolant enters the engine through the bottom hose, passes through the waterways in the block, head, manifold etc picking up heat as it goes.
the heated coolant then passes through the pump to the radiator where it is cooled as it drops to the bottom hose, then it all begins again