System Boilers vs Combi Boilers

Switching from a regular boiler to a system boiler can be beneficial if you're looking for a more efficient heating system with a faster response time and reduced space requirements (since system boilers don't need an expansion or feed tank in the loft). System boilers are also easier to install than regular boilers and can provide a more consistent water pressure. Consider this upgrade if you have a medium to large-sized property with more than one bathroom, as system boilers can cope better with higher hot water demands.

Upgrading to a system boiler might be a good decision if:

• You experience low water pressure with your current setup.
• You need to improve hot water supply to multiple bathrooms.
• You wish to remove cold water tanks from the loft to free up space or reduce the risk of freezing in winter.
• You're looking for a more energy-efficient heating system.

Disadvantages of a combi boiler include:

• Limited hot water supply: Combi boilers might struggle to supply enough hot water simultaneously to multiple outlets, making them less suitable for homes with multiple bathrooms.
• Water pressure dependency: The performance of a combi boiler is directly related to the mains water pressure. If the mains pressure is low, the output from showers and taps may be unsatisfactory.
• No backup hot water: If the combi boiler breaks down, you won't have access to hot water, unlike systems with a hot water cylinder that might retain hot water for a short period.
• Not always compatible with old radiators: In some older heating systems, the high water pressure from a combi boiler can highlight weaknesses in the system, such as leaks.

System boilers are connected to a hot water cylinder that stores a significant amount of hot water ready for use. While it's unlikely to "run out" of hot water under normal usage, the cylinder can be depleted if there's excessive demand. However, it will refill and reheat water continuously, so any shortage is temporary.

Yes, a system boiler requires a hot water cylinder to store hot water for domestic use. This setup allows the boiler to provide hot water more efficiently to multiple taps or showers at once, making it suitable for homes with higher hot water demand.

For a 4 bedroom house, especially with multiple bathrooms, a system boiler connected to a suitable hot water cylinder or a larger combi boiler is often recommended. The exact size and type depend on the number of bathrooms, the household's water usage, and whether the property has space for a hot water cylinder. Typically, a boiler with an output of 24-35 kW is suitable for such homes.

A 30kW boiler can comfortably support around 15-20 average-sized radiators. The exact number can vary based on factors such as the size and type of radiators, insulation quality of the home, and specific heating requirements. It's crucial to consult with a heating engineer to ensure your boiler's capacity matches your home's heating needs accurately.