Open 24/7 · 7 days a week info@btdplumbingheating.co.uk 07920 042880 HomeAboutServices Service Areas Our WorkReviewsContact07920 042880 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 - Home - Services - Power Flushing - 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 isA 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 forHomeowners 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 itBefore 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 mattersModern 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 ## The questions we're asked most Can't see yours? Give us a ring; we don't do sales scripts. Call 07920 042880 How much does a power flush cost?Depends on the number of radiators and system condition. We quote in writing after a short site visit. Free, no obligation. How long does a power flush take? Do I really need one before a new boiler? Will it damage my old radiators? How do I know it worked? Do you fit a filter as part of the flush? Do you cover my area? How often should a system be flushed? Can you flush the system without changing the boiler? Is there a guarantee? Free written quote · no pressure ## Radiators cold at the bottom? Get them running properly again. Book a quick site visit, get a written quote and, if a flush is the right call, get it done properly, filter, inhibitor and paperwork included. - Gas Safe 529962 - OFTEC C11108 - 18 years' experience 07920 042880Request a Free Quote Related services ## Often booked alongside Power Flushing All services Central Heating Systems Gas Boiler Installation Oil Boiler Installation Oil-fired heating specialists and fully qualified gas engineers, serving Broad Town and rural Wiltshire since 2007. Leave a review ### Services - Oil Boiler Servicing - Oil Boiler Repairs - Oil Boiler Installation - Gas Boiler Servicing - Gas Boiler Repairs - Gas Boiler Installation - Water Softener Installation - Central Heating Systems - All services → ### Service Areas - Broad Town - Royal Wootton Bassett - Broad Hinton - Lyneham - Wroughton - Marlborough - Yatesbury - Swindon - Calne ### Contact - 07920 042880 - info@btdplumbingheating.co.uk - Pye Lane, Broad Town, Swindon, SN4 7RRGas Safe Reg. 529962 OFTEC Reg. C11108 · Tech. 28212 City & Guilds Qualified Grant UK G1 Approved Installer © 2026 BTD Plumbing & Heating. All rights reserved. AboutContactPrivacyTermsCookiesOpen 24/7 · Mon–Sun Call NowRequest Quote