Central heating flushing advice from expert engineers

Is your central heating system ready for the change in seasons? Corrosion of pipes and radiators that create a “dirty” system can reduce its efficiency. As well as increasing heating bills, this can result in boiler problems that eventually cause it to break down. Regular central heating maintenance by a Gas Safe-registered engineer will help you avoid these issues.

This article looks at how you can care for your central heating system. We’ll discuss annual servicing, central heating flushing advice, and the difference between the most common ways of cleaning a central heating system.

A closed central heating system uses tap water for heat transfer. The water can gradually corrode the system from the inside. Inhibitor is added to the water to reduce this corrosive action, but if tap water is added to the system for any reason, this inhibitor will be diluted, and the rate of corrosion will gradually increase.

Corrosion causes the build-up of a dark sludge known as magnetite or black iron oxide, which can eventually cause your central heating to lose over 40% of its efficiency. It can also block the boiler’s pump and heat exchangers, speed up the corrosion process further, and result in system leaks.

Affected radiators can take longer to heat up and suffer from cold spots – typically around the centre and lower parts of the panels where the magnetite settles. Less efficient heating means your boiler has to work for longer, costing you more in gas bills.

Corrosion and sludge build-up can cause your boiler to display a fault code, but these codes can happen for several reasons. Only a Gas Safe-registered engineer can diagnose the fault for sure, then correct the problem fully.

Annual boiler servicing

Boiler manufacturers like Vaillant and Worcester Bosch require you to get your boiler serviced each year to keep its warranty valid. During the service, our heating engineer will check for faults and wear and tear, and make any tweaks needed to keep it running efficiently.

This is the most obvious form of central heating maintenance. However, most service providers won’t also test the water for signs of corrosion as part of an annual service. During the service, you can ask for central heating flushing advice and get maintenance tips for your particular heating system.

Get a magnetic filter installed

Having a magnetic filter installed is a good way of helping to keep a central heating system clean. Attached to the return pipework to the boiler, a magnet captures the iron oxide particles and stops them from circulating. The captured particles can then be removed during routine maintenance of the filter, which our engineers typically do during an annual boiler service.

Boiler manufacturers like Vaillant and Worcester will extend a warranty if a magnetic filter is included as part of a new boiler installation.

Water testing

Our engineers carry out a water test with every boiler service. It’s one of the most reliable ways to diagnose whether a central heating system is suffering from corrosion. It’ll also tell the engineer if inhibitor levels are low, and they’ll be able to give you all the central heating flushing advice you need.

We take a water sample on site and get it analysed by a third party, with the results shared with you on the day. These results confirm whether or not your system needs to be cleaned. Your engineer will also know for sure which type of clean would be most effective.

Chemical flushing

A chemical flush, also known as ‘chemical cleaning’ or a ‘chemical treatment’, is when an engineer fills your heating system with chemicals designed to lift, loosen and dissolve the sludge. The process takes around two hours to complete, depending on the size of the system.

The chemicals circulate through the system when it’s switched on. At the end of the process, these chemicals are flushed out, along with many of the solids that would otherwise be left to settle within the system. The system is then filled with clean water and the correct dose of inhibitor is added.

By getting a chemical flush when recommended by an engineer, you help protect your heating system and reduce how often you’ll need to pay for a power flush. Chemical flushing is a much quicker form of central heating maintenance and it’s also more cost-effective in the long run.

Power flushing

This is a full clean that removes the magnetite particles from your heating system. It’s also the most costly form of system clean because of the time it takes for the solidified mass of material to break up before being flushed out.

We recommend this type of system flush for heating systems with a lot of build-up i.e. those that haven’t been maintained regularly, and those with reduced heat output.

It typically involves:

1. Connecting a machine to the heating system, usually at the boiler or radiator
2. Pumping a cleaning solution through the system at high pressure to dislodge and remove the sludge
3. Flushing the solution through each radiator, pipe, and component to ensure they’re as clear of particles as possible
4. Removing the dirty water until the new water runs clear
5. Adding an inhibitor
6. Checking with a thermal camera and final testing to ensure deposits are removed

Aspect heating engineers are all Gas Safe-registered experts. We’ll be happy to give you central heating maintenance advice and discuss the most effective options.

Why not make sure your central heating system is maintained and ready for autumn and winter? You’ll have peace of mind going into winter and the knowledge you could be saving money on your gas bills.