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Power Flushing

Poor water quality is the No.1 cause of heating breakdowns. If your heating system is experiencing any of the following it may need a chemical Power Flush:

  • Radiators cold at the bottom but hot at the top
  • Heating slow to warm up
  • Some radiators not heating at all
  • Black or orange radiator water
  • Noisy or banging boiler
  • Radiators need frequent venting of air 
  • Multiple radiators pin-holing & repeated pump failures

How does a Power Flush work?

Power Flushing is a highly effective cleansing operation which works by pumping water at high velocity through the heating system. This loosens and mobilises harmful corrosion deposits and suspends them in the rapidly moving water. 

The pumping machine is connected onto the heating system by one of several different methods. Most systems may be flushed from a single connection point which negates the need to remove individual radiators. This makes for a quicker and cleaner job. 

Industrial strength cleanser is added to the machine and pumped at a temperature of 50-55 degrees around the heating system.  

To assist in breaking down and removing sludge at the bottom of the radiators, an agitation tool is used to vibrate the radiators. The water flow direction is rapidly switched directionally to churn the water which helps with disturbing sediment and sludge.  

During the Power Flush, all but one radiator is shut off. The one circulating radiator can now be Power Flushed individually from the central connection point. Once the radiator is cleared and is heating evenly all over, this process is repeated throughout the remaining radiators one-by-one. 

The water is pumped into a set of powerful magnetic filters which capture ferrous deposits, before being sent into the pumping machine reservoir ready to be drained and exited from the system. The heating water is gradually replenished with clean water. 

The water is then tested using a specially designed kit to ensure it is ready for dosing with anti-corrosion inhibitor. 

It is strongly recommend that the system is fitted with a good quality magnetic system filter which will continually remove ferrous deposits from the system. The filter is then cleaned at the same time the boiler is serviced each year. 


  • Boiler installation Power Flushes £420 inc.VAT
  • Independent Power Flushes £550 inc.VAT
  • Magnetic system filters approx £130 inc.VAT


The term 'system' refers to radiators and pipe work. 

Why is my heating water dirty?

There are a number of contributing factors that cause the system water to become dirty and chemical corrosion to attack the water sections internally. 

  1. Residual soldering fluxes 
  2. Poor cold feed and open vent configurations 
  3. F&E tanks allowing the water inside radiators to continually oxygenate 
  4. Electrolytic action whereby dissimilar metals attack each other 
  5. Old radiators rusting from within 
  6. Historical cast iron boiler heat exchangers once in use
  7. The biggest problem of all - ineffectively cleansed, flushed and inhibited systems at the point of installation

The older your system, the more likely it is to have inherent design flaws caused by outdated workmanship practices that are no longer in use today. Where this is the case, these issues need addressing first, before a Power Flush is carried out. 

Why is it cheaper to Power Flush on a boiler installation?

Elburton Heating charge a bespoke price for Power Flushing on boiler installs because much of the Power Flush preparation work is carried out at the same time as fitting the new boiler which results in a shorter power flush job duration. 

Does Power Flushing increase the pressure in the system and cause pipes to leak?

No. During the Power Flush the pressure within the heating system remains the same as it would under normal operating conditions. The Power Flush pump does however considerably increase the flow rate and velocity throughout the flush. It’s this increase in velocity and flow rate that enables the flushing pump to be effective at dislodging blockages and removing sludge.

It is a common misconception that Power Flushing is a ‘cause’ of leaks. If your system were to leak then this would identify a severe vulnerability within the heating system equipment that would likely have imminently developed into a leak.

It is better that the leak occur when a qualified professional is on site to immediately address the situation, instead of when the home owner / occupant is at work all day, on holiday or asleep at night. 

Does Power Flushing cause radiators to leak?

On exceptionally rare occasions radiators can develop small pinhole leaks due to scabs of rust being removed by the Power Flush. As mentioned above, the leak would have occurred at some point in the near future and the general consensus is that it’s better it happen whilst a qualified heating technician is on site rather than when you’re at work all day, on holiday or asleep at night.

Good quality radiators under 20 years old will be perfectly capable of withstanding a Power Flush. Older radiators fitted in the 60’s, 70’s and 80’s will be due replacement if they need Power Flushing. We would recommend you consider a new radiator pack if your existing radiators are past their working design life. 

My radiator valves are so old they can’t be turned off, is this a problem?

Yes. The Power Flush process involves turning the valves on and off to divert flow to individual radiators. A Power Flush can still be carried out despite the seized radiator valves but it will be much less effective. On some systems, it may be impossible to reinstate full flow around some radiators if they are stubbornly blocked and the valves cannot be operated.

If your radiator valves are defective, it is strongly recommended that new thermostatic and lock-shield valves are fitted as part of the job so as to allow for an effective Power Flush.

What happens if I still have a loft tank fitted to the heating system?

That’s fine. F&E (Feed & expansion) heating system tanks are manually cleaned and the connecting pipes capped during the Power Flush. Everything is reinstated at the end of the job. 

What’s the difference between black and orange water?

Black water is the result of magnetite caused by the presence of flux residues, electrolytic action and dissimilar metals attacking each other. Orange water is a sign of oxygenated water which can be indicative of poorly configured open vent and cold feed pipe work and historical cast iron heat exchangers. 

Sometimes, it may be necessary to reconfigure pipe work connections to stop air being sucked into the heating system at various points during the system cycle, as well as completing a Power Flush. 

My heating system flow has been poor from the point of install. Will a Power Flush overcome this?

No. If your heating system performance has always been poor since being installed, then a Power Flush will not improve performance. Radiators may be tepid to touch due to undersized pipe work, poor system design, undersized boilers or inadequately rated pumps. 

A well installed system should be fit for purpose from the outset. We recommend you take up any issues with the company that carried out the installation or enlist a reputable company such as Elburton Heating to correct the installation or design defects first, before considering spending money on Power Flushing.

How long does a Power Flush last?

There is no definitive answer to this. It depends on how old your system is, the quality of the boiler, radiators and auxiliary fittings such as pumps and diverter valves. 

However, as a rough guide, a good quality Power Flush should last for around 15-20 years. This is provided the system isn’t interfered with and contaminated by flux residues or the inhibitor drained and not replenished. 

Why are Power Flushes so expensive?

Prices of Power Flushes can appear expensive. As a general guide, a good quality Power Flush should cost approximately £400 - £600. A certain well known national company now charges £1000 for a Power Flush!

Elburton Heating use an industry leading Kamco flushing machine and renowned Adey magnetic filters together costing £2000. This equipment has to be maintained, serviced and repaired. This comes at a considerable cost to Elburton Heating. 

The specialist chemicals used during power flushing cost circa £60 - £80 per job. 

Power Flushes are also very labour intensive procedures taking a full day for an average sized system and longer for larger properties.  

Be wary of companies promoting cheap and quick Power Flushes. In our experience, the jobs are rarely completed satisfactorily and can result in another Power Flush being needed.