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

With an immersion heater there is no external fire heating the boiler vessel or any part of it. The immersion heating element does not come in contact with anything structural in the boiler. While the excessively high heat that can weaken an exposed crown sheet and lead to failure, an overheated electric element will simply fry itself in short order when it becomes exposed and will not create any risk for boiler failure.