Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I agree with @Junkologist.  What you don't want to happen is pour water off the side of the tank (say when filling it) and get the heater soaked (avoid that but it happens, so let it dry when it does).  Or have such a leak you are streaming water into the heater (fix that leak).

I've had to replace a number of heaters and I expect the 1st case as the biggest problem and it is likely compounded with heavy (tap) water.  The water boils/steams away but not the minerals.  So use filtered water with a mixture of distilled water, not tap water.  I'd don't even use "spring water".  In my area in central Texas, the tap water is crazy hard!