Heat Only Electric Boilers | For Open-Vented & Gravity-Fed Heating Systems

About

A heat only Electric Boilers — sometimes called a regular boiler, conventional boiler, or electric flow boiler — is designed to work with open-vented heating systems that use a feed and expansion (F&E) tank, typically located in the loft. Electric Boilers provides central heating only, circulating hot water around your radiators or underfloor heating circuit. Like a system boiler, it does not produce domestic hot water directly — hot water is handled separately by a cylinder or immersion heater. This type of boiler is the right choice when you are replacing an existing regular gas or oil boiler on an older open-vented system and do not wish to convert the pipework to a sealed pressurised system. Heat Only vs System Boiler — What's the Difference? This is one of the most commonly confused distinctions in heating, and getting it wrong can cause real installation problems. A heat only (regular) boiler works with an open-vented system — one that is not pressurised and relies on a small cold water feed and expansion tank in the loft to maintain the water level and accommodate expansion. The system operates at low, gravity-fed pressure and does not require a pressurisation unit or sealed expansion vessel on the boiler itself. A system boiler works with a sealed, pressurised system — it typically includes an internal expansion vessel and circulating pump, and the system is filled to a set pressure (usually 1–1.5 bar) directly from the mains. System boilers are designed to work with unvented cylinders at mains pressure. The simplest way to identify which type of system you have is to check the loft. If there are one or two small cold water tanks feeding your heating circuit, you have an open-vented system suited to a heat only boiler. If there are no tanks and your heating system has a pressure gauge and filling loop, it is already a sealed system suited to a system boiler. Can You Convert from Open-Vented to Sealed? Yes — it is possible to convert an open-vented system