Hi. I had to replace a leaking shower hot water handle. I closed the valves and drained the water from the bathroom sink and shower. Got the shower handle replaced with no problem, but now my heating system sounds funny; almost like it is draining. Also, the hot water is constantly running through the system. It's a hot water radiator system that runs off my furnace. I cannot find anything leaking. I have hot water through the whole house and the heat is working.

I'm wondering if maybe I got air in the plumbing? Maybe I need to bleed the system?

Yes air could have got into the plumbing but usually if you run the water or bleed the system it will correct itself.