Your guide to system boilers.
What are system boilers?
A system boiler is made up of two parts. The normal boiler you’re used to seeing in your kitchen or air cupboard, and a separate cylinder for storing hot water. This means that system boilers are capable of providing a constant supply of hot water throughout your home, and are commonly found in larger homes which have a greater demand for heating and hot water.
System boilers explained.
Check out our quick video guide and learn if it could be the right boiler type for your home.
How do system boilers work?
System boilers provide hot water and central heating slightly differently depending on whether they’re a gas-fired system boiler or an electric-powered system boiler.
For gas-fired system boilers which are connected to the mains gas, firstly a flame heats up water in an enclosed hot water system. A coil in the water cylinder carries the central heating water at high temperatures through the cylinder, heating its contents and getting the hot water to where it needs to be.
Electric-powered system boilers work in the same heat but use an electric heat exchanger to warm up the circulated water rather than a gas flame.
This means that the water that comes out from the taps is from the cylinder, rather than the boiler, as it’s constantly being pumped through the coil in the hot water cylinder and the radiator system.
What’s the difference between a system boiler and a combi boiler?
Whilst system boilers have a water storage cylinder which can store hot water for when it’s needed later, combi boilers are a stand-alone heating system and only heat water on demand. This means that combi boilers take up much less space than system boilers, ideal in smaller homes.
Because they don’t store hot water, new combi boilers are suitable for homes with one to three bedrooms and one bathroom as they’ll struggle to meet the needs of a larger household.
System boilers are able to manage the requirements of a large home as they can manage the hot water requirements of multiple radiators, taps and even underfloor heating.
What’s the difference between a system boiler and a regular boiler?
Regular boilers, or heat-only boilers, are similar to system boilers in that they also store hot water for later use. They are often found in large houses, such as four bedroom homes, and come with a header tank, or feed and expansion tank, in the loft.
This header tank in the loft keeps the regular boiler artificially under pressure and also uses an external expansion vessel to maintain the water pressure. System boilers have a pressurised heating circuit and use an internal expansion vessel.
This means that regular boilers often take up more space than a system boiler and can require more complex piping between the water storage tank and boiler. Because of this, system boilers are more commonly installed in modern properties with multiple bathrooms.
What are the advantages of having a system boiler installed?
Hot water from multiple taps at the same time.
Ideal for larger homes which have a high hot water demand, for example if you have multiple bathrooms.
Good water pressure.
The hot water comes directly from the mains instead of a water tank, which means you’ll get good water pressure.
No tank in the loft.
Unlike a regular boiler, you won’t need a tank installed in your loft, perfect if you’re considering that loft conversion.
Works with solar energy.
Because system boilers have a separate hot water cylinder, they can be compatible with solar panels or solar thermal.
How much do new system boilers cost?
That depends on a number of factors including:
The size of heating boiler needed to warm your home.
If you need to move your boiler system.
If you’re switching from a different boiler type, such as a combi boiler, or keeping like-for-like.
Any installation costs.
Are system boilers expensive to run?
System boilers are designed for larger homes and properties, where they’ll be more cost effective than a combi boiler or regular boiler.
The boiler installation costs might be a bit higher, however the aim will be to save money over time as the heating system will be designed to make the use of the water cylinder and ensure you can use multiple hot water points at the same time.
However if you’re in a smaller home then it may be more cost effective to have a combi boiler or regular boiler.
Why choose a Worcester Bosch boiler?
They’re fast and economical to run.
Worcester Bosch boilers are A-rated for efficiency, guaranteed to be 94% efficient, helping you to reduce your energy bills.
Smart connected thermostats.
Control your central heating and hot water with the wireless Bosch EasyControl, plus get easy-to-understand graphs on gas consumption and how efficient your heating programmes are.
Awarded Best Buy by Which?
The Greenstar 4000 combi, is a leading Which? Best Buy. The Greenstar range uses advanced technology to create powerful boiler systems with modern designs to suit your home’s needs.
What are the disadvantages of a system boiler?
Like any type of boiler, there are several points to bear in mind before you pick a new boiler system:
More space is required for the cylinder.
Busier times (when you have lots of visitors for example) may mean you have to wait for the cylinder to reheat.
May need to add insulation to stop heat and energy loss.