Overflow kits?

[rmleal]

I got a AGA with overflow kit and my question is. Is there a fail safe in case it loses suction or how does it work not to fail or does it??

 

[Behrmon]

Internal overflow or HOB?

 

[rjdudek]

If it is the megaflo kit it does not use suction. As the water level rises it runs down the drain.