Noise from water heater

[bob600]

My water truma water heater just randomly started making a clicking noise when used...mainly when tap shut off.
It's an old one.
Everything works but wondered if sign of maybe it don't soon!
Any thoughts?
Bob

 

[Cush]

You sure it’s coming from the boiler. Sounds like a thermostat but no idea if it is a sign of an impending failure. Others with more experience will be along to help soon I’m sure.