CENTRAL HEATING - Types of System
Its easy to be confused by the different types of boiler and heating systems available. Our simple guide is designed to help you make the right choice for your home.
The most popular types of fuel systems used in the UK are:
- Natural Gas
- LPG (Liquified Petroleum Gas)
Other types include Solid Fuel (coal and wood burning) and green energy products such as solar and ground source heat pumps.
The type of system you choose will normally depend initially on the location of your property. Where Natural Gas in available this is normally first choice due to its cost and convenience. In rural areas with no Natural Gas supply the choice is more complicated. In simple terms LPG although more convenient tends to be more expensive than oil.
Types of System
Although there are other variations, there are 3 main types of heating system:
- Combination (Combi)
- System boiler with unvented hot water cylinder
The key difference between these types of heating system is in the way they provide hot water in your home. All provide heating to your radiators in a similar way.
In a conventional system hot water is heated indirectly by the boiler and stored in a cylinder. Hot water in the cylinder is pressurised by water from a header tank that is usually located in the loft - along with a smaller header tank for the heating circuit. Hot water pressure in your taps will be determined by how far below the header tank they are. This may mean that you don't have sufficient pressure for a shower upstairs.
Combi systems provide instaneous hot water heating. This means that you don't need to have a hot water cylinder or a storage tank in the loft. For this reason Combis are good for smaller properties including flats. However there are disadvantages. Flow rates, how much hot water comes out of your tap or shower, are determined by the capacity of the boiler. In addition, when a second hot water outlet is opened the flow rate will drop. This can mean that Combi systems aren't ideal for properties with high occupancy and particularly those with multiple bathrooms.
System Boiler with Unvented Hot Water Cylinder
A system boiler is simply one in which all of the major components of the heating system are built into the boiler including the heating pump and expansion vessel. The latter component does away with the need to have a seperate feed & expansion tank (as found in a conventional system) in the loft. System boilers are often combined with an unvented hot water cylinder. Although similar to a conventional hot water cylinder, the unvented cylinder has one key advantage - it is fed and pressurised by the mains water. This has 2 important advantages; firstly there is no need for a loft storage tank; secondly your hot water will be supplied at near mains water pressure.
What about Condensing Boilers?
Each of the three types of system above can use a condensing boiler (or a non-condensing boiler). "Condensing" refers to the fact that these boilers have a way of recovering heat from their flue gases that would otherwise be lost to the atmosphere. In this process water droplets that are present in the flue gases are "condensed" inside the boiler - hence the name. The efficiency advantage of condensing boilers is significant. Typically condensing boilers have energy efficiency ratings of 88-95% compared to non-condensing boilers at 75%.
Which is Right for Me?
The right boiler system for you will depend on your property and your personal circumstances. For example for a single person living in a flat a Combi system may be ideal. Alternatively a large family may benefit from a system boiler/unvented cylinder approach. At H20 Heating Ltd we will take time to discuss your circumstances and your requirements so that we can provide you with the most appropriate system.
Contact H2O Heating now for friendly help & advice