System boilers are often referred to as sealed system boilers. They can be used with a hot water storage cylinder as a standalone heating system or as part of a renewable heating system, such as solar thermal. The system is filled directly from the water mains, so there’s usually no need for a cold water tank in the loft. And an electric immersion heater within the cylinder means you can still have hot water even if your boiler breaks down. The Vaillant range of ecoTEC Plus system boilers stocked by Mr Central Heating is available in various heating outputs, meaning there’s a model suitable for almost every home.