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  • The Power Flush
    Radiator on the left is blocked with sludge.

    The Power Flush

    If like most people these days you have central heating fitted within your property that uses radiators,

    then the chances are you are going to need the power flush at some time.

    So how do you know if you need the power flush?

    One of the first things you will notice is the radiators take a little longer to heat up than they use to,

    if you find a radiator always needs to be vented because it’s cold at the top and warm at the bottom.

    When you vent the radiator you may notice that the water is a very dark colour,

    your boiler may be noisy when it’s running.

    These are all signs that your central heating system needs a power flush.

    When your central heating was first installed, it should have been flushed then to

    remove all the excess flux and little bits of debris from within,

    but if your system is over tens of years old then this may have been overlooked.

    Flushing the central heating system when new has always been advised by the boiler manufactures,

    but it takes time so most never got flushed.

    Now we have what is known as a benchmark, this is a list of procedures that the installer has to follow.

    With ever boiler comes to a benchmark book; it may be located at the back of the boiler installation book.

    This benchmark book has to be filled in by the installer and signed and dated.

    One part of the benchmark, asks has the system been flushed, and if so, with what.

    You can flush with just water for a new system, or you can use a flushing chemical.

    Once a system has been flushed out, then an inhibitor should be added to

    prevent any sludge build up within the system.

    This inhibitor should be checked every year,

    IE when you have your annual boiler service, to see if it needs to be topped up.

    If you drain the system down for any reason or even just remove a

    radiator for decorating then you will need to top the inhibitor up.

    With a power flush, you are removing all the sludge build up within the system,

    but I get asked a question a lot, how does the sludge get there?

    The answer is, the water that we fill the system with has many impurities within it.

    Yes, it’s the same water we drink from our tap, also you have many different types of metal within the system,

    IE steel, copper, brass, cast iron and soon. All these metals react with one another within the water.

    This is what causes the sludge build up. It does not take long for this to start happening.

    I personally am not a lover of power flushing unless the central

    the heating system is really sludged up and basically not working at all.

    My reason for this is over the years I have worked in this industry,

    I use to use a power-flushing machine, but I found that it could also cause

    leaks on the system, normally on a radiator.

    After speaking to the makers of the power flush machine,

    they told me that if a system was over tens of years old then you

    have a one in ten chance of a leak appearing in a radiator, this is because of the sludge lodges in the

    waterways of the radiator and starts to corrode the radiator,

    so when the sludge is removed it can leave a small pinhole leak.

    So how do I power flush a central heating system?

    I use a chemical call system restorer, you add this to the system via the header tank,

    or if you have a sealed system then you will need to drain

    some water off then adds the chemical through a radiator.

    Once you add this you will need to run the system for around 24 hours for it to start cleaning.

    This is a milder way of flushing your system.

    Depending on the make of chemical you use you can leave it in the system, you don’t have to drain it off.

    I use a chemical that can stay in the system, so it’s always cleaning;

    it lasts for around 24 months. You can also add the inhibitor to work alongside it.

    If you have a power flush on your central heating system,

    you will also notice a small difference in your gas or electric bill as the

    boiler once clean does not have to work so hard to heat up your radiators.

    Ask your Gas Safe Registered boiler engineer

    to check your system for sludge build up, it’s easy to check.

    I always tell my clients to look after their boiler and the boiler will look after them. It’s just like a car,

    if you never have it serviced or checked it will let you

    down when you need it most, that’s the same with your boiler.