94 E320 Hose?

[bobsdynamic]

Hi,
Can anyone tell me what a certain hose would be called as it needs replacement. It's a "Y" type heater hose located by the brake booster that sprung a leak the other day One end went to the engine the other went to the heater core and the third went down somewhere? I cut out the "Y" and connected the two leads going from engine to core with an adaptor. I was stuck on the highway and had to get going so I left the third hose disconnected. That happened three days ago and I haven't noticed and problems yet. That third hose doesn't leak water. What could it be feeding? I need to know what that hose would be called so that I may order one. Thanks for any help.
Bob