Ajax valves are usually found on the bottom of a hot water cylinder. There is usually a pipe that goes from the ajax valve through the ceiling and comes out the roof. This is where water will generally leak from if the ajax valve has blown.
Occasionally, this pipe will go through your walls and vent outside directly into the drainage system. If you can hear water running or dripping on the roof (and its not raining) then it is probably the ajax valve.
If you have an issue with your ajax valve you should contact a plumber.
Last Reviewed: 08/06/2016