Powerflush questions, answered

A deep clean of your central heating system. A machine pushes water and cleaning chemicals through the boiler, pipes and every radiator at high flow but low pressure, washing out the sludge, rust and debris that build up over time.

Common signs are radiators that are cold at the bottom, rooms that are slow to warm up, dirty water when you bleed a radiator, a noisy boiler or pipes, and repeated boiler breakdowns. It’s also recommended when a new boiler or new radiators are fitted.

If your radiators have cold spots, the water is black when you bleed them, or the boiler is noisy or keeps breaking down, yes: it deals with the cause rather than the symptoms. If your heating works evenly and the water runs clear, you probably don’t need one, and we’ll tell you so.

We use top-of-the-line professional powerflushing equipment, the best in the industry. That means we can complete a full home powerflush in a single day, leaving your system clean and clear. You’ll need to be in, and the heating and hot water will be off for part of the day.

It depends on the system. What keeps it clean afterwards is the inhibitor we add (it slows corrosion), a magnetic filter to catch any new debris, and having the filter cleaned and inhibitor checked at each annual boiler service.

There’s no set schedule. Do it when the signs appear, and when a new boiler or radiators are fitted.

A chemical flush helps, but a powerflush machine moves water much faster, reverses the flow and flushes each radiator in turn, so it shifts far more of the sludge that has settled.

Most powerflushes cost £500–£1,000, depending on how many radiators you have and the size of your system. We give you a free, fixed price before any work starts. Ask about our current winter offer, or use the quote form for a price for your home. More in our guide: how much does a powerflush cost?

Powerflushing uses low pressure, so it’s gentle on pipework. On very old systems a flush can sometimes show up a weak joint or radiator that was already close to leaking. That’s why we ask about leaks first and check everything before we start.

Often, yes, with care. Microbore pipes are narrow, so they clog more easily and need checking first. Tell us when you ask for a quote and we’ll advise.

Cleaning the system before a new boiler goes in stops old sludge from flowing straight into it, and boiler manufacturers expect the system to be clean. Check your new boiler’s warranty terms.

Sludge has settled in the bottom of the radiator and blocks the hot water. Bleeding won’t fix it; a powerflush will. Read the guide.

Air or gas is trapped at the top. Bleed it. If it keeps coming back, corrosion inside the system is making gas, which is a sign the water needs cleaning and protecting. Read the guide.

Black water is magnetite: rust from the inside of your radiators and pipes. It’s the same stuff that turns into sludge. Read the guide.

The hot water is going round the pipes but not through the radiator. That’s usually a blockage of sludge in the radiator or its valves, or a stuck valve. We check the valves before flushing.

If some radiators are slow or patchy, sludge is often restricting the flow, so the boiler runs longer to reach temperature. Thermostat settings, insulation and the boiler itself matter too, and we’ll look at the whole picture.

A rumbling or kettle-like noise from the boiler. It’s usually caused by sludge or limescale restricting the water flow over the heat exchanger, so the water overheats in spots. A flush often helps, and we’ll check whether scale is also involved.

Kettling is a warning sign, not something to live with. Book a Gas Safe engineer to look at it. If you ever smell gas, turn off the gas at the meter and call the National Gas Emergency line on 0800 111 999.

Yes. Inhibitor slows corrosion inside the system, and a magnetic filter catches new sludge before it can build up. With a powerflush, inhibitor is always added, and a magnetic filter is fitted if your system doesn’t already have one.

No. We protect floors, run hoses tidily and clean up before we leave. Customers regularly mention how tidy Pete and Riley are.

Yes. Kent Powerflush is Gas Safe registered, number 660156. You can check any engineer on the Gas Safe Register.

Yes. We’re fully insured, and every job is guaranteed: if any work we’ve done or any part we’ve fitted isn’t right, we’ll come back and put it right.

Yes. As well as powerflushing we fit, service and repair boilers and central heating. Powerflush customers get a discount on a future boiler or system upgrade.

Yes, through our sister company Addisons Plumbing & Heating. It’s the same engineer, Pete, and the same phone number. Kent Powerflush is the dedicated powerflushing side; for repairs, boiler installs, bathrooms and kitchens, visit addisonsplumbing.co.uk or just call us.

East Kent: Faversham, Canterbury, Whitstable, Herne Bay, Thanet (Margate, Broadstairs, Ramsgate), Sandwich, Deal, Dover, Folkestone, Ashford, Sittingbourne and the villages around them. Not sure? Just ask.

Yes. Someone needs to be in for the day, and the heating and hot water will be off for part of it.

Yes. Between tenancies is a good time, as the property is empty and the heating is ready for the next tenant.