Do I need a central heating Power flush?

What is a power flush?

A Power flush is a process in which chemicals are added to your system which are designed to break down the magnetite and sludge circulating in your system. Once these chemicals have broken down these particles, a power flush machine is attached, and the system is flushed out of any unwanted dirt.

Reasons you may need a power flush-

  • Your radiators are not heating up as quick as they used to.
  • Part of the radiator is hot but not all of it.
  • Some radiators do not heat up at all.
  • You’ve been advised that you need a power flush because you’re having a new boiler installed.

I see it far too often where a power flush has been performed but did not cure the fault. This misdiagnosis is a waste of time and you’re money.

Lets take a look below at how we may be able to determine if a central heating power flush is needed or not. 

Your radiators are not heating up as quick as they used to.

  • If you have on/off controls, it may be a case of checking the boiler flow temperature and increasing it.
    • If you have modulating controls, you may have to change the curve set point of which your system has been set too. Please keep in mind modulating controls are designed only to input the heat needed in to heat your property so the radiators may not always appear to be fully on.
  • Your system may need balancing.
    • If radiators close to the boiler heats up quicker than say radiators that are further away.
    • We can do this by throttling down the lockshield valve side of the radiator, by doing this to the radiators that are close to the boiler we force flow to the radiators that are further away. An efficient heating system is one that heats up evenly.

Part of the radiator is hot but not all of it.

  • I would try to bleed the radiator of air first. If air is present, the top of the radiator will not get hot.
  • If the bottom of the radiator is cold, but the top is hot, this may be a good reason for a power flush. I would confirm this by using a thermal imaging camera; you would be able to see a collection of sludge formed at the bottom of the radiator.

Some radiators do not heat up at all.

  • Firstly, I would ask whether this radiator has ever worked before. Common sense can generally point you in the direction of rectifying the problem.
    • For instance, If you have added to an existing system, then the boilers pump may not be big enough to cope with the extra demand.
    • An additional pump would need to be added via hydraulic separation.
  • Has it been drained down recently or the system has not been used in a long time (3 months plus)
    • This would point me to an airlock in which should be fairly easy to fix by shutting all working radiators and forcing the flow through the affected radiator.
  • If none of the above worked, then you may have a blockage. Blockages generally need to be cut out and will not be rectified by a power flush.
  • Is the lock shield valve open and the TRV in the open position?
    • The TRV pin may be stuck and needs to be freed or the valve may need replacing.

You’ve been advised that you need a power flush because you’re having a new boiler installed. 

  • This is not always the case. Many manufacturers do insist that the water quality is checked and that it is of a satisfactory standard. The point I’m making is that just because your heating system has been installed for a number of years does not mean it is full of sludge and debris. Many factors contribute to corrosion, I have seen 10-year-old systems which are clean as a whistle and the opposite for a system which is 5 years and corroded heavily with many debris.
        • A sample of the heating water should be taken to determine whether a power flush is needed.
        • A thermal imaging camera can be used to see if a build-up of sludge is present in the radiator
    • A test to see if the system is heating up properly prior to installing the new boiler. We always test for defects on the heating system and highlight these prior to starting.
  • Alternatively, to a power flush, I like the Magnacleanse method in which when the new boiler has been installed, a large twin magnet is temporarily hooked up to the heating system via the boiler return pipe. The magnacleanse is left on the system for a minimum of 2 days. This method should collect all magnetic particles in the system. When we come to remove the magnacleancse we can see how bad your system is full of debris and an educated decision can be made as to whether a full power flush is needed.

I hope some of the above scenarios can help you make an educated decision as to whether you need a power flush or not. Just remember it not always clear cut, but like any fault-finding exercise, the fault in question should be confirmed to be the problem before proceeding to spend all that money on a power flush!