Power Flush for Central Heating: How It Works & How Long It Takes
Over time, central heating systems get clogged up.
Power flushing is one of the best ways to fix this.
Read on to learn what it is and how it’s done.
What is power flushing?
A power flush (sometimes written as powerflush) is a popular and effective method of cleaning metallic and corrosive sludge (sometimes called magnetite) that accumulates in your central heating system.
This sludge is generally made up of:
- Rust
- Dirt
- Debris.
Removing this sludge and its associated blockages extends your system’s lifespan and helps it work more efficiently.
Does my central heating system need a powerflush?
It’s not always possible to see the problems caused by build up in your heating system.
In fact, in our experience at YourRepair, build-up of contaminated water in the system is a contributing factor in 87 per cent of boiler breakdowns.
Common signs that you need a power flush include:
- Leaking pipes
- Radiators are cold, have cold spots, or slow to heat up
- A boiler breakdown
- Excessive noise from your boiler or central heating pump
- Discoloured or no water escaping when you bleed radiators
If you’re connecting a new condensing boiler to an old system, you’ll also need to do this before you start up your new boiler.
Otherwise, the internal pipework can become damaged causing the boiler to breakdown.
Sometimes, this damage may even mean it’s more cost-effective to replace the entire system.
Not every system is suitable for a power flush
Electrical heating systems and radiators with twin entry valves are not compatible with power flushing.
And if your pipework is smaller than 15mm in diameter, it will require an alternative approach.
Power flush or chemical flush?
If only one or two radiators are performing poorly, you may be able to have them chemically flushed.
It uses the same combination of chemicals as a power flush, but without the addition of the pump.
This method can help maintain the system or address any localised problems between each power flush.
How power flushing works
Pump connection
During a powerflush, a powerful pump unit is connected directly to your central heating system.
Depending on whether you have a combi or system boiler, the powerflush pump will connect to the pump head or circulation pump.
It can also be connected across the tails of a radiator.
Pumping process
Once connected, the pump flushes a powerful blend of chemicals through the pipework.
It dislodges blockages and build ups.
Next, your heating engineer will force clean water through the pipes.
This removes all the contaminated liquid from the system before it’s properly disposed of.
How long does a powerflush take?
This really depends on the size of your home, and what central heating system you have.
Vented systems
For example, for a 3-bedroom house with a vented system, a power flush may take around 5-6 hours.
It also depends on the severity of the problem and whether any parts of the system need replacing.
However, the entire job should take no longer than a day.
Sealed systems and combination (combi) boilers
All else being equal, powerflushing for sealed systems and combination boilers typically takes less time.
This is because it’s not necessary to cap off the expansion piping or cold feed.
So, a three-bedroom house may take around 4 - 5 hours.
Powerflushes require professionals
Powerflushes should always be conducted by a qualified professional, either a plumber or heating engineer.
They will have the training and level of expertise with handling and combining the chemicals involved.
They’ll also be able to identify problem areas and replace any parts of the system that have become damaged.
Once the power flush is finished, you’ll receive a certificate to prove that the procedure has been carried out by a qualified professional.
Balancing your radiators after a power flush
A power flush changes how water flows through your heating system.
So, immediately after a power flush is when balancing your radiators is strongly recommended.
It provides a recalibration that ensures even heat distribution.
Don’t be tempted try to powerflush yourself
Firstly, you could be putting your health at risk.
Powerflushing requires handling dangerous chemicals in potentially unpredictable heating systems.
Secondly, you could damage your central heating system.
And also invalidate any warranty.
These would leave you out of pocket if something goes wrong during the flush or later on.
How often do central heating systems need a powerflush?
A powerflush should always be performed when a new system is installed or a new boiler or radiator added.
If your system is correctly maintained, then a powerflush should only be necessary once every 3 - 5 years.
The precise timeframe depends on your many factors, including:
- Your system’s age
- Local water hardness
- The type of metals in your pipework and radiators (see below).
However, as part of your annual boiler service, your heating engineer will perform a visual inspection of the system.
They should be able to identify any problem areas where corrosion damage has occurred and inform you of the risk of leaks.
They’ll also be able to tell you whether a powerflush is necessary to remove any blockages.
The importance of metal types
How much build up there is of sludge, rust, etc. in your system is largely dependent on:
- The type of metal used for your heat exchanger
- Whether there are vulnerable spots where different types of metal pipework have been joined together.
For example, a copper heat exchanger won’t corrode as quickly as the steel in your radiators.
Care for your system
Central heating system problems are inconvenient - and potentially expensive.
At YourRepair, we offer home cover plans starting from £9 per month, providing you with access to over 5,000 expert gas safe engineers across the country.
Enjoy the peace of mind of knowing that you are covered from the shock of sudden repair bills.
For immediate cover, simply call our friendly UK-based call centre now on 0330 162 2325 today.