Power flushing in Bromley

Ours start at £450 including VAT for up to six radiators, £520 for seven or eight, £620 for nine to eleven and £750 for twelve to fifteen, with £35 for each radiator above that. Chemicals, inhibitor, a magnetic filter and the certificate are all in that price. The national directory guides quote £350 to £800 ex VAT while the same directory’s Bromley page quotes £745 to £1,728, which tells you more about lead fees and VAT presentation than about the job.

Three reasons. It is a full day of skilled labour for one or two engineers, not an hour. The machine itself is a real capital cost, around a thousand pounds and upwards for a Kamco, Norstrom or Fernox unit that an engineer has to buy and maintain. And the consumables are not trivial: cleanser, descaler for hard-water systems, neutraliser, inhibitor and a magnetic filter. Where a quote looks unusually cheap, it is usually because it is a chemical flush being described as a power flush, or because the filter and inhibitor are billed as extras afterwards.

Yes, and this is the single most common practical problem. A proper flush isolates and cleans each radiator individually with the flow reversed, so every radiator needs to be reachable, including any boxed in, sitting behind a fitted wardrobe, in a loft conversion or in a locked room. On shared circuits in converted flats around Penge and Beckenham, one radiator sometimes sits in a neighbour’s property, and that access has to be arranged in advance. Where we genuinely cannot reach a radiator we tell you on the quote and note it on the certificate rather than flushing round it.

It is if the diagnosis is right, and it is not if the diagnosis is lazy. On a system with multiple radiators cold at the bottom, black bleed water and a kettling boiler, a flush restores circulation, cuts warm-up time and usually takes a noticeable amount off the gas bill, as well as keeping a new boiler warranty intact. On a system where one radiator is cold because a thermostatic valve pin has seized, a flush is several hundred pounds spent on the wrong problem. We test before recommending, and we regularly tell people they do not need one.

Most manufacturer warranties are conditional on the system being cleaned to BS7593 and protected with inhibitor. Worcester Bosch, Vaillant, Ideal, Baxi and Glow-worm all include wording of that kind, and Worcester and Vaillant additionally require a filter for their longest warranty terms. The practical risk is not that you never had a cleanse — it is that you cannot prove it. A flush with no certificate, no recorded inhibitor dose and no filter fitted is a flush that will not defend a warranty claim on a blocked heat exchanger. That is why we issue the paperwork as standard.

A compliant one records the property and date, the machine make and model, the chemicals used with batch numbers, the dwell and circulation times, the water clarity and TDS readings before and after, the volume of inhibitor dosed and the make of filter fitted, and the engineer’s name and Gas Safe number — ours is 919881. A certificate that says only "power flush carried out" with a signature is not evidence of anything. If you are having a flush done specifically to satisfy a warranty condition or a home cover provider, ask what the certificate will record before you book.

BS7593:2019 is the British Standard for treating water in domestic hot water central heating systems. It applies to any system being cleaned, filled or refilled. Three parts of it are routinely ignored: it requires the system to be cleaned, dosed with inhibitor and protected with an in-line filter, and it requires the system water to be tested at least every five years thereafter, with the result given to the householder. A flush carried out without dosing inhibitor and fitting a filter does not meet the standard, whatever the invoice calls it.

It is a full day with the heating off and some disruption, and there is a real risk on old systems. High flow through corroded steel pipework, or through radiators that have been quietly thinning from the inside, can turn a weeping joint into a leak and can find a pin-hole that was going to appear anyway. It is more common on gravity-fed open-vented systems and on microbore where a valve has not been moved in decades. We survey for that first, and on genuinely fragile systems we recommend a gentler chemical cleanse rather than taking the money.

Rarely, and much less often than on open-vented systems. A sealed combi system already runs at pressure, usually 1 to 1.5 bar, and a power flush machine works at around 2 bar with high flow rather than high pressure, so it is not applying anything dramatic. The genuine risks on a combi are elsewhere: dislodged debris finding its way into the plate heat exchanger, and old rubber-sealed compression joints that have gone hard. We isolate the boiler from the circuit during the flush for exactly that reason, and fit the filter before recommissioning.

They price per job after their own assessment rather than publishing a table, and reported figures sit well above the local market — commonly £600 to over £1,000 for a typical three-bedroom house, with HomeCare policies sometimes requiring a flush before cover is granted. We publish our prices by radiator count so you can compare directly. If a cover provider has told you a flush is needed before they will insure the boiler, ask them in writing whether they accept a third-party BS7593 certificate, because most do and it is usually cheaper.

Four to eight hours for a normal Bromley house, so plan for a full day with the heating off. Small flats with four to six radiators can finish in a morning. Larger properties with twelve or more radiators, heavy sludging, or microbore needing valve conversions can run into a second day, and we will say that at quote stage rather than on the day.

You can hire the machine, but it is a poor idea for most people. The machine is the easy part. Knowing which radiator to isolate, when to reverse flow, how long to dwell a descaler on a hard-water system, how to neutralise properly so nothing acidic is left in a heat exchanger, and how much inhibitor a given system volume needs, is the actual work. A badly run flush pushes loosened debris into the boiler rather than out of the system, and self-flushing produces no certificate, which means it will not support a warranty claim later.

Yes, in practice. An air source heat pump runs at much lower flow temperatures than a gas boiler and is far less tolerant of restricted circulation, so the system has to be genuinely clean before it goes on. Installations funded through the Boiler Upgrade Scheme require the system to be cleansed to BS7593, and the certificate forms part of the handover paperwork. If a heat pump is on your horizon in the next year or two, it makes sense to time the flush with that work rather than paying for it twice.

A properly inhibited system with a magnetic filter that is cleaned at every annual service should not need flushing again for a decade or more, and many never do. What it does need is the five-yearly water test BS7593 asks for, which we carry out during a normal service and takes minutes. Where a system is being flushed every three or four years, something is wrong — usually a leak drawing in fresh oxygenated water, or inhibitor that was never topped up after a radiator change.