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What is a central heating Powerflush?

A power flush is a cleansing process carried out by a heating engineer which is designed to remove dirt. sludge, rust and debris from the boiler, pipes and radiators that may have accumulated within your system over time. If these substances are left in your heating system, they could cause blockages or corrosion and ultimately reduce the efficiency of your boiler - they could even eventually lead to a breakdown.

A power flushing machine sends water through the heating system at a higher flow rate so as to dislodge any build-up of sludge, rust and other debris in the system and it is used in conjunction with various chemical treatments.

Signs your system needs a Powerflush?

Cold spots on your radiators, particularly if they are hot at the top but cold at the bottom.
Radiators require more bleeding & venting frequently and you find discoloured water when radiators are bled.
Pipework up to the radiator gets hot but the radiators themselves do not.
Some radiators do not heat up to the required temperature even when the radiator valves are turned up fully.
Flow from the boiler or heat pump are hot but the return is cold.
The boiler constantly needs to be restarted.
The central heating takes a long time to heat up.
The system is noisy with gurgling, cracking and banging noises.

The build-up of sludge in your heating system can take years to take effect however, with the introduction of British Standards BS 7593 2019 becoming compulsory on 15 June 2022 under the Building Regulations Part L, you must also comply with the manufacturer's installation instructions which state that you must install and maintain your heating system to comply with this standard.

What is Sludge and more specifically what are the types of sludge inside my central heating system?

Magnetite Sludge
Magnetite, commonly referred to as heating system sludge, is a black substance comprised of dissolved and rusted metal from the radiators of your central heating system. It forms naturally by anaerobic corrosion which is also known as hydrogen corrosion. If you bleed your radiators you sometimes notice a foul smell, that is the hydrogen gas inside your heating system. Inhibitor needs to be added to the system to prevent the build up of hydrogen gas, if not it can have a devasting effect on the boiler and heating system.

Iron Oxide Sludge
Iron oxide sludge which is commonly referred to as heating system sludge is a red/orange colour and is more common in over aerated heating systems. It is caused by the ingress of oxygen into the system. Magnetic sludge and oxide sludge both are heavier than water and tend to deposit themselves at the low flow areas within the system, for example radiators, low lying pipework, hydraulic vale assemblies and plate heat exchangers. In many situations iron oxide sludge is worse than magnetite sludge because of the higher presence of oxygen.
If you have your heating system flushed and inhibitor added and then tested annually for inhibitor and maintain the correct level of inhibitor, you will dramatically reduce the build up of magnetite sludge within the heating system.

Microbiological Contamination
The presence of bacteria specially in poor maintained open vented systems does have a serious cause for concern due to the build-up of legionella bacteria which can build up in open vented feed & expansion cisterns (feed & expansion tanks). Feed & Expansion tanks have been obsolete for over 20 years and should be replaced with sealed system kits, the new configuration will have a significantly lower risk of exposure to the legionella bacteria. Some plastic pipes allow the ingress of oxygen into the system water. Unfortunately some early plastic pipework is now deemed to be unsuitable for the installation of certain heating system pipework, this problem has been overcome by the addition of an oxygen barrier being fitted into the pipework by the manufacturer.

What are the benefits of getting a Powerflush?

Enhanced energy-efficiency.
Improved system reliability.
Potentially lower energy bills.
Reduced likeliness of boiler breakdown.
Could increase system lifespan.
Radiators can warm up quicker.
Better quality of heating and hot water.
Reduced noise from boiler and radiators.

How much does a Powerflush cost?

The price will depend on the size and number of radiators in your home.

For a property of up to 8 radiator's a full system Powerflush would cost £720 Including VAT
For a property of up to 16 radiators a full system Powerfulsh would cost £960 Including VAT
For a property with over 16 radiators an additional charge per extra radiators would apply.

But remember with AOS you can spread your payments over 3, 6 9 or 12 months Interest free!

How long does a Powerflush take?

Most of our Powerflushes take between half to a full-day appointment however this will depend on the size of your home, how many radiators you have and how blocked or dirty your current heating system is.

What's included in the Powerflush?

Each radiator is isolated and flushed individually.
A full Magna cleanse on the system to carried out.
A full system drain down, de-sludge with a chemical inhibitor added afterwards to prevent future build-up.
2 Year Warranty subject to terms & conditions.*
*Please read our terms and conditions for more details.

What is a Magna Cleanse?

Magna cleanse is a method of flushing and cleaning out a heating system by utilising the heating system's standard pump and not the use of a high flow rate pump. Developed by Adey, it is used in conjunction with their magnetic filter and radiator vibrator/agitator tool. AOS only carry out a power flush in conjunction with the Magna Cleanse System, this gives the benefit of reversed flow and very powerful magnets to cleanse the system quickly.

Do i need a Magnetic Filter installed with a Powerflush?

It is essential when carrying out the powerflush that we also install a magnetic filter on completion of the works if one is not already fitted so as to comply with BS 7593;2019 building regulations. A magnetic filter is a device that collects magnetic debris within a heating system. The filter will attract any corroded metals and delay any future build-up of sludge. The filter allows water to continue flowing through the system as normal and can keep a system as cost-efficient as possible for longer and prolong the effects of the Powerflush.

How much does a Magnetic Filter cost?

The Cost to supply and install a Magnetic Filter is £288 Including 20% VAT.

What causes the Corrosion?

Corrosion is generally a process of oxidisation of metals which in a central heating or cooling system is promoted by the following:

Incorrect, unsuitable or poorly applied or maintained water treatment products.

Ingress of air, for example, at the mechanical or poorly soldered joints.

Some plastic pipe allows the ingress of oxygen into the system water, unfortunately some early on plastic pipework is now deemed unsuitable for the installation of certain heating systems, this problem was overcome by the addition of an oxygen barrier being fitted, in modern pipework a vapour barrier layer is fitted.
In some cases you may not be able to identify the substandard pipework but where it is identified it is recommend to be replaced.

Poor system design and installation, examples; oxygenation of the circulating water by replenishment, system pumping over or sucking down on the open vent, incorrect sizing of the cold water feed pipe, inadequate sized or incorrectly installed feed & expansion cistern (F&E Tank), incorrect configuration of feed & expansion tank.

The presence of installation materials in the system water, examples, flux residue jointing compound, this is a residue cleaner foreign matter left over from inadequate cleaning or flushing. Oil greases left over from the manufacturing process of system components.

Certain characteristic of the system supply wate, for example, some naturally soft waters with low alkalinity and low PH are generally more corrosive to system metals. Some water may contain high levels of aggressive irons, example, higher chloride levels can promote pitting of metals.

The presence of bacteria, especially in poorly maintained open vented systems does have a serious cause for concern due to the build-up of legionella bacteria in open vented (F&E tank systems) which are now obsolete and should b replaced with a sealed system confoguation which will significantly lower the risk of exposure to legionella bacteria.

The comments is section 5 are highly unlikely within the South of England as the water is deemed to be hard but it can be a problem if people have had water softeners installed.

Interesting Facts

87% of all system breakdowns are the result of sludge in the heating system water.
A newly installed A+ Energy Efficiency rated Boiler will lose efficiency within 6 days if the system is contaminated.
A healthy clean system will reduce fuel wastage and save money on your bills.
With a sludge free system and magnetic filter fitted you can save as much as 12 to 15% on your energy bills.
Repair bills as a result of sludge in the heating systems across the UK cost on average £700 million per year.

SOURCE; Fernox and Sentinel technical literature and website information