All gas central heating systems using hot water to provide heat produce iron oxides (Magnite) and other debris. It has long been recognised that the presence of these materials within gas central heating systems leads to a drop in heating efficiency and a shorter life for boilers and other components. Carrying out power flushes and adding an inhibitor when a new boiler is fitted are effective ways to minimise this potential problem . Increasingly, fitting a magnetic filtration device to the system is being used to further reduce the risk of on-going damage to central heating systems.
Magnetic filters come in two types. Some use magnetic technologies to remove iron oxides only. Others use both magnetic and non-magnetic technologies to remove iron oxides, and non-iron sludge and debris in the water. Manufacturers claim they remove virtually all debris.
Typically, magnetic filter devices are fitted to the water return pipe near to the boiler itself. Magnetic filters are relatively non-bulky and are easily fitted to either horizontal or vertical pipework. They have no moving parts and an electrical supply is not required.
Filters are available to fit either 22mm or 28mm pipes and they are compatible with most gas domestic and commercial central heating systems.
Filters should be emptied annually and this can be done as part of the annual service. Emptying is a simple process which can be completed within a few minutes.
Fitting a magnetic filter does not significantly impede the flow of water within the system. They are designed so that the flow of water continues even when the filter becomes full, although when full they no longer effectively remove debris from the water.
Magnetic filters also provide a convenient point at which to take water samples or add chemical to the water.
Benefits of Magnetic Filters
By ensuring that the water in gas central heating systems remains clean, magnetic filters offer a number of potential benefits:
The system continues to operate at a high level of efficiency
There are no cold spots in the system, for example where a radiator has become clogged with debris
The lifetime of the system and its components is maximised
There are fewer repairs and breakdowns
Carbon emissions are reduced
Overall maintenance costs are reduced for landlords and tenants experience lower heating costs
There is limited statistical information on these benefits, although one manufacturer claims that their technology can lead to a reduction in heating energy consumption of 6% per year and a 250kg reduction in carbon emissions each year in a typical three bedroom home.
When to Fit a Magnetic Filter
Whilst there may be some benefits in fitting a magnetic filter to any gas central heating system at any time, the most appropriate time to fit one is when a new boiler or other major components are fitted. In this respect, magnetic filters need to be seen as one part of a more comprehensive approach to reducing the effect of iron oxides and debris in heating systems which includes:
A power flush to remove any existing dirt in the system
A chemical inhibitor to reduce the build-up of iron oxides, lime scale and other materials within the system
A magnetic filter to catch and remove any iron oxide or other debris that forms within the system during its lifetime
Magnetic filters cost between around £80 to £140 per unit (unfitted and excluding VAT) depending on the manufacturer.
These costs need to be seen in the context of the cost of a new boiler and the potential for using a filter to extend its life, reduce repairs and lower the rapidly increasing heating costs for homeowners.