pump hose leaking !!!!!!!!!!

Hi everyone,
I had someone from work who is an engineer come and help me get my heater going. It was going, and today when I went to check, I have a huge water leak, like a constant fast drip from one of the hoses. It is the hose from the heater to the pump. I tried to tighten the hose and I cant. I turned my pump off so I dont lose more water. Is it because the hose was cold, and warmed up?? I turned my heater off also, and the pilot light.I have lost alot of water since I have been gone a few days. Does anyone have any idea what I can do?? I thought I would ask the engineer back tomorrow, but if I can fix it on my own, I would do it.
Timmie