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Power Flush vs Chemical Flush and Magnacleanse - Which is Best?

Firstly, what is a power flush?

Heating System Power Flush A power flush is essentially a deep, intense cleanse of your heating system and type of boiler, which aims to improve the quality of your system’s water by removing sludge, rust and other random bits of crud.

These troublesome residues can cause issues if left to fester in your system - and let's be honest, festering crud is never a good thing. In fact, poor quality heating water is one of the leading causes of boiler breakdowns in the UK.

Dirty water = dirty boiler = dirty great big repair bills.

Want to find out what type of boiler is best for your home, along with costs? Use our free calculator to find out now 


If not flushed regularly the water can also become dense, impacting its efficient flow through your system, and even causing blockages. This can reduce efficiency, result in pesky “cold spots” in your radiators and reduce the effectiveness of your radiators overall heating ability.

Boiler busted from bog standard water? Get a fixed price on a new replacement from £1,595.

When do you need a power flush?

In the perfect world, a power flush (or any flush for that matter) should be performed every 5 to 6 years, this will ensure the quality of heating systems water is maintained to a high standard and help prevent damage to metallic components, as well as the development of blockages.

However, most homeowners opt to have a power flush prior to having a new boiler installed (especially if their existing heating system is old as mould).

Heatable complete a chemical flush on all new boiler installations, for free

If the existing heating system isn't old as mould, a chemical flush is usually sufficient (Heatable do this as standard on all new boiler replacement, for free). More on that later.

How much will a boiler installation cost? Check out our new boiler costs guide for the full rundown. 

Top signs your system needs a power flush

  • Radiators that need to be bled consistently 
  • Radiators with cold spots 
  • Central heating takes a long time to provide an adequate heat output 
  • Cold radiators even when the pipes are hot 
  • Radiators with discoloured water 
  • A boiler and heating system that is noisier than it was previously 
  • Certain radiators in your home that do not heat up
  • Radiator leaks 

If your heating system is experiencing any of the above problems, then it may be time to have your system power flushed.

However, bear in mind that the above may be caused by some other underlying issue and not necessarily be related to the quality of your heating water.

If the heating water in your system has been naughty for a long, long time, it's heat exchanger may well be busted. If it is (and your boiler is super old anyway), you could consider buying a new boiler from £1,595. We can fit anywhere in the UK within 24 hours. Get a quote for a new boiler online.

Under no circumstance should you start tinkering with your gas boiler by yourself, for the love of god, do get a professional in.

Benefits of a power flush

There are many, but mainly to...

  • Prolong the life of your boiler e.g. helps prevent a faulty heat exchanger
  • Improve the energy efficiency of your heating system 
  • Reduce the risk of rust and corrosion to key components 
  • Prevent and remove blockages in your system 
  • Ensure radiators do not suffer from “cold spots”
  • Improve the flow rate of water through the system, increasing the speed of heating 

How does a power flush work?

First, an engineer will do a visual check of your heating system to make sure it can take the punishment of a power flush.

Then, your heating system will be hooked up to an external incredibly powerful pump, similar to a Hadron Collider (ish).

Boiler System SludgeIf you have a combi boiler, they will attach the pump via the pump head, but if you have a system boiler, it will be attached via the circulation pump. The pump will then deliver a toxic blend of chemicals into your system under so much pressure, that only a single mother under a conservative Government could relate.

The cocktail of chemicals used includes a descaler to help remove limescale, a corrosion inhibitor to help prevent the formation of rust and a specific chemical to help dislodge rust and remove sludge or crud.

Sounds complicated, how long does it take? A power flush typically takes around a day to complete, but the exact time in hours can vary depending on how large your heating system is e.g. the number of radiators in your property, as well as the severity of the water contamination.

And don't worry, the powerflush includes a complete boiler power flush as well as the radiators and associated pipework. 

Learn all about combi boilers in our what is a combi boiler guide. 

How much does a power flush cost?

Power Flushing Cost

The cost of a power flush is typically dependant on the size of your home and it's heating system.

If you've got a whopping great house with loads of rooms, it's understandably going to cost more as the engineer will be ripping through the chemical cocktail at a much greater rate.


On average, most households find that they pay around £300 for a power flush, but if your engineer discovers any problems that need to be fixed along the way, you should be prepared to pay for the cost of repairs, additional labour and the replacement parts. 

The cost of a power flush may sound high, but, in the long-term, it's worth it's weight in sludge.

Would you buy a brand new car, and top it up with gravy? Exactly.

Can you do a power flush yourself?

DIY Power Flush

While there are no rules that restrict who can carry out a power flush, it's always recommended that you use a professional Gas Safe engineer. 

Although there are 'do it yourself' kits and you can buy the equipment yourself, the reality is that a power flush is an incredibly dirty job. Moreover, if you experience any issues along the way, you will likely need the assistance of an engineer anyway.

It's the kind of job you'd have a crack at, and mid-way through think "what on earth was I thinking?"

Far more importantly, however, is that your boiler manufacturers warranty may be invalid if the power flush is not carried out by a professional who provides you with official certification that it was completed by an actual engineer and not a Nutty Professor.

If you do have a crack at it by yourself, and it all goes horribly wrong, we can fit you a new boiler within 24 hours. Get a quote online in 60 seconds.

Interested in paying for your boiler monthly? Check our boilers on finance guide, for the full run down. 

Power flushing FAQ's

1) Can you power flush a combi boiler? AKA a boiler powerflush 

If you are installing a brand-new boiler, then it is advised that you carry out the power flush before installation (if your existing system is very old), since you risk contaminating the new boiler with dirty water and debris that may cause damage. 

However, if you intend on power flushing an existing combi boiler, it is fine to do, since the boiler likely has its own debris that needs to be cleared. 

If your existing system isn't too old, and in a generally good state, then a standard chemical flush will suffice.

2) Can a power flush cause a leak? 

It is a myth that a power flush can cause leaks, the water is passed through the system at a high velocity but at low pressure (2 bars). 

Yet if there is any debris that is cleared from the system during the process, then it is possible that a leak could be exposed. However, it is far better for an engineer to be present and ready to fix the leak immediately. 

Want to know which boiler power is right for your home? Check out our "what size boiler do I need" guide.

3) What's a central heating powerflush? 

During a powerflush, your entire central heating system is cleansed. This includes both a boiler powerflush and a central heating powerflush, as well as the associated pipework. The chemicals will circulate through the whole system, so there's no need to be concerned about this slight difference in terminology. 

4) Can you power flush a microbore system?

As the name suggests, microbore systems are composed of pipework that has an extremely small diameter – typically just 8 mm, which can cause issues for power flushing, although it is still possible. 

In general, manufacturers advise that a chemical cleanse is carried out on these systems before a power flush. The reason for this is to ensure as many tough deposits are loosened and removed before the main flush. 

Power Flush vs MagnaCleanse

What is the difference between a power flush, chemical flush, and a Magna cleanse? 

What is a power flush? 

As previously discussed, a power flush is a deep clean of your central heating system using various chemicals and high pressure in order in to remove dirt, debris, and rust to improve the quality of your heating water. 

What is a chemical flush? 

A chemical flush is different from a power flush and is essentially a more basic cleanse. Unlike a power flush, it does not require high pressure and is instead delivered through the system using the natural water flow and gravity. 

The chemicals are then left to circulate within the system, helping to remove debris, dirt, and rust. After a while, the system is then flushed, replacing the system with new, clean water, a rust inhibitor is also added to the water to help protect your boiler and metallic components from the formation of rust. 

What is a Magna cleanse? 

A Magnaclense is a high-tech cleansing method that is used to give your central heating system a thorough clean, working to remove even the most stubborn residues and magnetites. In fact, it can remove more sludge within 20 seconds than can be extracted within 30 minutes without it. 

Want to have your boiler moved to a different location? Check out our "cost of moving boiler" guide.


A Magnacleanse filter can also be installed onto your system to provide long term protection. This continually helps to collect sludge and debris as water flows through your system. 

Power flush conclusion

A power flush is an effective way to give your central heating system a deep clean and maintain the quality of your heating water.

In turn, this prevents harmful debris, sludge, and crud from wreaking havoc in your system and absolutely wrecking it.

At Heatable, we offer you the ability to add a power flush (or Magna Cleanse) service onto any of our boiler installs, allowing you to ensure your system is clean and that your new boiler is free from potential contaminants from day one. 

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