Both regular and system boilers store hot water in a cylinder, but they differ in their configuration::* **Regular boiler (conventional boiler):** The most traditional type of boiler system. It takes up considerable space due to the separate tanks..* **System boiler:** A more compact system, as some components are integrated within the unit itself. It doesn't require a separate feed and expansion tank, saving some space. If you're unsure which type of boiler is best for you, consult with a Gas Safe registered heating engineer.