heater hose question

[BANJOPICKER]

I know this was answered a while back but I for got the answer so shoot me which hose is the supply hose to the heater box I want to install a cut off valve to help the AC DON in Virginia

[Jeep Craze]

If it is a V-8, you can't put in a shutoff valve due to that perticular loop is crutial to the cooling system. That is a main part of the circulatory system. Now a bypass valve you can install, one that would conect the two hoses together w/out going through the heater core. Not sure how the inline 6's are?