heater hoses

I'm about to hook the hoses to my heater. The engine is a 305 Chevy. I have 1 hose from the top of the water pump to the heater core the other from the intake manifold to the heater core. My question is which hose is the inlet? I want to install a shutoff valve on the inlet side so the heater is not getting any hot water in the heat of the summer, assuming it (summer that is) ever returns.
Thanks.

 

Intake manifold hose.

 

Really dont make any difference,,As long as there is no water flowing,your heater will not get hot..