How does a system boiler work?

A system boiler, or sealed system, is a great option if you have more than one bathroom or your household has a high demand for hot water. Here are some of the most frequently asked questions about system boilers.

How does a system boiler work?

A system boiler contains all the major components of the heating system, including the pump and expansion vessel, which means installation is quick, neat and efficient. The boiler heats the water in a hot water storage cylinder, such as the Megaflo Eco, which in turn heats the water in the central heating system via a coiled heat exchanger and provides hot water to taps and showers.

Do I need a system or combi boiler?

If you have a high demand for hot water, for example, if you have more than one bathroom or shower room, a system boiler may be the perfect choice for you.

Will I need a separate expansion tank in the loft?

There is no need for a feed and expansion cistern in the loft if you have a pressurised unvented hot water storage cylinder.  If you have an open vented hot water cylinder, you will need a cold water storage cistern in the loft.

Can system boilers supply several taps at once?

A system boiler is perfect for homes with multiple bathrooms; hot water is provided by a storage cylinder, so no matter how many taps you turn on, water will not run cold elsewhere in the house.

What other controls do I need with a system boiler?

Since the Building Regulations changed in April 2018 (commonly known as Boiler Plus), time and temperature controls are required for all boiler installations.

Who can install a new system boiler?

All gas work carried out in your home should be done by a Gas Safe registered engineer. The Gas Safe Register is the official list of gas engineers who are registered to work safely and legally on boilers, cookers, fires and all other gas appliances. You can find your nearest Baxi Gas Safe registered installer by using our Find an Installer tool.