How long does a power flush take?

A typical 8–12 radiator system takes a full working day. Larger or heavily sludged systems can spill into a second day, we'll tell you at survey, not on the day.

Do I really need one before a new boiler?

Nearly always, on a system more than 8–10 years old. Every mainstream manufacturer specifies a flush or thorough chemical clean before installation as a warranty condition.

Will it damage my old radiators?

A properly conducted power flush uses low pressure and high flow, it doesn't stress the system. Where a very old radiator is on its last legs the flush can occasionally expose an underlying leak, which is better found now than after a new boiler is fitted.

How do I know it worked?

Radiators run hot top to bottom evenly. Water samples before and after are photographed. Boiler runs quieter, uses less fuel. We hand you a written report.

Do you fit a filter as part of the flush?

Yes: a magnetic system filter and fresh inhibitor are included as standard. That's what protects the value of the flush for years afterwards.

Do you cover my area?

Swindon, Royal Wootton Bassett, Broad Town, Broad Hinton, Wroughton, Lyneham, Marlborough, Yatesbury, Calne and surrounding villages.

How often should a system be flushed?

With a filter and correct inhibitor concentration, most systems only need a flush at boiler-replacement intervals (10–15 years). Without those, sooner.

Can you flush the system without changing the boiler?

Yes: it's often the right call on systems 8+ years old with cold radiators, even if the boiler is fine.

Is there a guarantee?

Workmanship is guaranteed and any parts (filter, inhibitor) carry their manufacturer's warranty. Full written report on completion.

Power-flushing machine connected via red hoses to a wall-hung boiler for a full central heating system flush

Radiators cold at the bottom?

Power flushing thatactually restores a sludged system

A proper, chemical-and-mechanical power flush that removes years of magnetite sludge, restores full flow to every radiator, and protects new boilers from the warranty-voiding fouling that follows a rushed install.

Request a Free Quote 07920 042880

18 years' experience · Manufacturer-approved procedure · Written before-and-after report

18 years

Experience
£2m cover

Public liability
Included

Filter fitted
Correct dose

Inhibitor
Free

Written quote

Overview

A straight explanation of what we do, and why it matters

Central heating systems collect black magnetite sludge silently, year after year. Left long enough it blocks radiators, wrecks pumps, damages new boilers and quietly voids the warranty on your last install.

Back to home

What it is: A full power flush using a high-flow, low-pressure pumping unit, targeted chemical cleaner and heat, individually flushing each radiator until the return water runs clear, followed by a magnetic filter, correct inhibitor dose and a written report.
Who it's for: Homeowners across Swindon, Royal Wootton Bassett, Marlborough, Calne, Broad Town and the wider Wiltshire area with radiators running cold at the bottom, noisy boilers, repeat pump failures, black-water bleeding or a new boiler booked in for installation on a system older than ten years.
When you need it: Before every new boiler goes on an existing system, every reputable manufacturer now requires it. Also whenever radiators are cold at the bottom despite bleeding, pumps have failed repeatedly, or system water bleeds out black.
Why professional matters: Modern condensing boilers have narrow, precise heat-exchanger waterways. A modest amount of sludge from an old system can foul a new heat exchanger within a heating season. Skipping the flush is one of the most common reasons a five-figure boiler installation ends up with a rejected warranty claim.

The cost of leaving it

What happens when it's ignored

A £700 power flush before a new install saves the £2,500 heat-exchanger replacement two winters later.

Risks & escalations

Cold spots at the bottom of radiators mean sludge, not air, bleeding will never fix it.
Sludge blocks strainers, wears pumps prematurely and cracks pump seals.
Fouled heat exchangers reduce efficiency and force the boiler to run at higher flow temperatures; the exact opposite of what a condensing boiler is designed for.
Manufacturers routinely reject warranty claims where system water testing shows uninhibited or heavily contaminated water.
Left long enough, sludge causes internal corrosion, pinhole leaks in radiators and pipework are the end-game.

Common mistakes

Assuming a 'chemical flush' with a bottle of cleaner and a drain is the same as a power flush. It isn't.
Adding inhibitor to a system that hasn't been flushed. It doesn't remove the sludge that's already there.
Skipping the magnetic filter after the flush. Nine tenths of the value of the flush is protected by the filter.
Doing it during a new-boiler install with the cheapest quote in the pile. Corners get cut, and it's your warranty at risk.

A power flush isn't glamorous. It just quietly saves the next boiler and the last twenty years' worth of radiators.

Our process

A clear, five-step system, no surprises

Step 1

System condition test

Sample the system water. Test for inhibitor concentration, iron content and pH. Confirm whether a full flush, chemical clean or top-up is what the system actually needs.
Step 2

Connect the flushing unit

High-flow, low-pressure pumping unit connected in place of the circulation pump or via a tapped point on the flow and return.
Step 3

Circulate, agitate, drain

Cleaner and heat circulated through the system. Each radiator flushed individually | pipes agitated to lift the sludge | dirty water drained until return runs clear.
Step 4

Fit filter and inhibitor

Magnetic filter installed on the return pipework, fresh inhibitor dosed to correct concentration, system pressure-tested.
Step 5

Written report and handover

Before-and-after water samples photographed, filter position and inhibitor product listed, warranty-safe paperwork left with you.

The benefits

Concrete outcomes, not vague promises

Full radiator heat restored

Every radiator hot top to bottom again | no more cold spots that bleeding can't fix.

Fuel savings

A clean, unrestricted system lets the boiler run at lower flow temperatures | real, measurable fuel savings.

Warranty protected

A properly flushed system, filter fitted and inhibitor dosed | exactly what manufacturers require after installation.

Longer boiler life

New heat exchangers stay clean. Pumps last. Valves keep sealing.

Quieter running

No more kettling and banging from restricted flow through the heat exchanger.

Documented before-and-after

Water samples photographed, filter fitted and shown to you, inhibitor product and concentration recorded.

In detail

The technical stuff, explained straight

Where the theory meets the van. Materials, methods, brand differences and the specific situations we deal with week in, week out across Wiltshire.

What magnetite is and why it wrecks systems

Magnetite is the black iron oxide sludge that forms when untreated water reacts with the internal steel of radiators and pipework. It's magnetic, hence the black paste that sticks to a magnetic filter or a pen magnet on the pipework. Over years, without proper inhibitor, magnetite settles at the low points of the system: the bottom of radiators, the base of vertical drops, the strainers on pumps and diverter valves. It blocks flow, wears pumps and, in modern condensing boilers, fouls the tight waterways of the heat exchanger. A power flush is the only reliable way to remove it once it's built up.

When power flushing is (and isn't) the right answer

Right answer: cold radiators at the bottom, repeat pump failures, black-water bleeding, sludge visible on a magnetic filter, new-boiler install on a system 10+ years old. Wrong answer: air-locked radiators (a different problem, solved by bleeding and repressuring), leaks (need to be found and fixed first), or a system that's fundamentally undersized (needs radiator changes, not a flush). We test the system water first, if a full flush isn't needed, we'll say so.

What separates a good power flush from a poor one

A proper flush uses a purpose-built high-flow, low-pressure pumping unit, not the boiler's own pump, and each radiator is isolated and flushed individually, one at a time, with the flush pump agitating the pipework and radiator to lift settled sludge. Chemical cleaner is used at the correct concentration and dwell time, with heat applied where possible. Post-flush, the system is drained and refilled with clean water, dosed with fresh corrosion inhibitor at the correct concentration and, critically, a magnetic filter is installed on the return so future magnetite is captured, not recirculated.

Filters and inhibitors | the invisible half of the job

A magnetic system filter (Fernox TF1, MagnaClean Professional 2, Sentinel Eliminator or similar) catches magnetite before it can settle in the boiler heat exchanger. It's a five-minute annual check on a service. Combined with a correctly dosed inhibitor, 1–2% concentration, Fernox F1, Sentinel X100 or the manufacturer's specified product; the system stays clean for the boiler's warranty life. Skipping either turns a good flush into a temporary fix.

Chemical clean vs full power flush

On systems where sludge is modest and the customer wants to minimise cost, a hot chemical clean (circulating cleaner through the system for a period, then draining and refilling) can be adequate, especially at the same time as a boiler swap. It's cheaper than a full flush but less effective on heavily fouled systems. We'll be honest about which is appropriate for your system after water testing.

FAQs