Power Flushing
"Power Flushing" is a term that you may have heard in reference to a central heating systems but not fully understand what a Power Flush is, why is it done or how much it will cost. In this article we have tried to provide the answers to those questions and others that you may have.

What is a Power Flush?
  • The process by which a build up of sludge composed of rust, scale, tiny metal particles and other debris is removed from a central heating system.
  • A mixture of clean, mains water and chemicals is pushed through radiators at high pressure by a pump like machine.
  • Usually it is done as a three step process - although it can be more if there is a large accumulation of sludge.
  • If you really want a step by step guide then CLICK HERE to access the website of Sentinel, the manufactures of machines used for power flushing.

Why would a power flush be needed? 

  • A build up of sludge decreases the efficiency of a boiler as well as putting an increased strain on it making it more likely to breakdown.
  • A power flush, properly carried out, will lead to more even heat distribution throughout the property, energy savings and so lower bills, as well as extending the life of the boiler.

How do you know if your central heating needs a power flush?

There are tools available that can indicate if a system is in need of a power flush from samples of the water in the system. Some engineers will have this tool but frequently an experienced engineer will be able to advise you following an inspection of your central heating system. A power flush is not always the best solution to a poorly performing heating system, it has for example been suggested that British Gas engineers receive incentives to sell power flushes.
  • Symptoms that a central heating system may be in need of a power flush are:
    - Some rooms being colder than others
    - The system taking long time to warm up
    - Radiators being cold at the bottom
    - Radiators requiring frequent bleeding
    - Increased noise from your boiler
  • You could also try a test of holding a magnet to the underside of any plastic or copper pipes. It the magnet sticks or feels "Sticky" when you pull it away then there is likely to be a build up of sludge in the pipe.

How often does it need to be done?

  • The answer is really, "When it is needed" some websites on the internet suggest every three years. However, a properly set up and maintained system is unlikely to experience such a rapid build up of sludge.
  • It is prudent, though not essential, to do it when an old central heating boiler is replaced. Many boiler manufacturers do in fact make their warranty dependent on flushing and cleaning of the system at installation.
  • Fitting a "Magnaclean" to "catch" the metal residue that sludge is mostly comprised of will also reduce the regularity with which a power flush is required.

What does it cost? / How long does it take?

  • Given that "time is money" the length of time a power flush takes will directly affect how much it costs.
  • The time it takes depends on the size of the central heating system (how many radiators there are) and how dirty the system is (how much sludge has built up).
  • Done properly it will take at least a morning but this could extend to a day or more for very large houses or dirty systems.
  • As a guide, a seven radiator house will cost in the region of £350 to £500 excluding VAT. We would suggest that you beware of people offering to do it for £200. In our experience they won’t be doing it right. Be sure they fully explain what they will do before you give them approval to proceed.

Who can do it?

  • A power flush should be done by a central heating professional who works on gas boilers and central heating systems all the time.
  • Strictly speaking anyone could buy or hire a machine and do a power flush (as long as they don’t touch the Gas!) and there are short (3 hour) courses that how to do a power flush.
  • At HomeForce we'd only ask a Gas Safe registered engineer to do a power flush. It will be done far better than one done by someone who has just completed a 3 hour course.

Any "words of warning"?

  • Water is pumped round at high pressure so it may find weak spots and cause leaks though these can often be sealed with a leak sealer.
  • If left for a long time sludge can go as hard as concrete and a power flush will be much less effective. Pre-power flush treatments with chemicals a week or two before the actual power flush can alleviate this, but leave it too long and you may cause the boiler to break down or even need replacing.
  • It can be possible to clear a sludge build up by putting an additive in the system water, allowing it to circulate for a couple of weeks, and then draining-down and refilling the system in the normal way. This can be cheaper though arguably not as effective as a power flush.

And finally?

  • Regular, basic maintenance of your central heating system - including keeping the system water topped up with inhibitor and the fitting of a Magnaclean to prevent corrosion and sludge formation - will greatly reduce the need for power flushing.

To arrange for a Gas Safe Registered engineer to power flush your central heating system contact us on 0131 315 0000, complete our Request-A-Visit form or email us on info@homeforcegroup.co.uk