This question is an exact duplicate of:
My gas water heater, continuously lets hot water out from the outlet (seems it is connected to tp valve, it goes through the wall to outside the home).
If I turn the water heater to low (much below the normal setting with the recommended arrow), it stops after a few minutes.
What could be the problem and I am worried if this is something dangerous, in addition to wastage of water and gas..?
Also, I noticed that my heater is making more noise than ever..It is a 3-4 years old heater..