Power flushing clears sludge, rust, and debris from your central heating system. If your radiators are cold at the bottom, your boiler is noisy, or the house takes ages to warm up, a flush is often the fix. We only recommend it where the condition of the system actually justifies it.
Power flushing — Edinburgh & the Lothians
Power flushing that clears the sludge and gets every radiator hot again.
Cold spots, slow warm-ups, and a noisy boiler are usually sludge rather than a dying system. Most Edinburgh homes are flushed in a day, typically for £400–£800, and we will tell you straight if yours does not need it.
Gas Safe registeredMost systems flushed in a dayInhibitor and filter fitted properly
20+
Years' Experience
Yes
Gas Safe
Yes
LPG Certified
Power flushing
Most flushes
Done in a day
Typical cost
£400–£800
Engineers
Gas Safe registered
What It Is
A deep clean for the water inside your heating system.
A power flush is a proper clean-out of your central heating. Over the years, the water inside a system corrodes the inside of the radiators and pipework, and the iron oxide that comes off settles as a thick black sludge — usually along the bottom of the radiators, where the water moves slowest.
That sludge narrows the passages the water has to travel through, including the fine waterways inside the boiler's heat exchanger. The result is the set of symptoms nearly every customer describes the same way: radiators cold at the bottom, rooms that never quite get there, a house that takes an hour longer to warm up than it used to, and a boiler that has started making noises.
A power flush connects a separate high-flow pump to the system — one that moves far more water than your boiler's own pump ever will, and can reverse the direction of flow through each radiator in turn. Combined with a cleaning agent, that is what physically lifts the settled sludge out rather than rinsing past it.
On the equipment
Power-flushing kit is fairly standard across the trade — Kamco is the best-known name for the pumps and chemicals, and plenty of engineers in Edinburgh use it. What actually decides whether a flush works is not the badge on the pump: it is whether the engineer takes the time to isolate and agitate every radiator individually, or just circulates cleaner round the system for an hour and calls it done.
Signs You Need One
Six signs your system is silted up.
You do not need all six. Two or three together, especially cold radiator bottoms plus dark bleed water, is a system telling you fairly clearly what it needs.
Radiators cold at the bottom
The classic one. Hot across the top, cold along the bottom third, because iron oxide has settled where the water sits still. One radiator can be a one-off; three or four means the whole system is silted.
The house takes ages to warm up
If the heating needs an hour longer than it used to before the place feels right, circulation has narrowed. The boiler is working just as hard — the heat is not reaching the rooms.
Kettling, banging, or a noisy boiler
That rumbling kettle noise is debris trapped in the heat exchanger causing the water to boil in patches. It is a warning, not a quirk — left alone it shortens the life of the boiler.
Black water when you bleed a radiator
Clean system water runs clear. Dark grey or black water with grit in it is corrosion product circulating through your boiler, pump, and valves every time the heating fires.
Some rooms hot, others never get there
Upstairs roasting and the back room cold can be a balancing problem — but where the cold rooms are also slow and the water is dirty, sludge is usually blocking the flow.
Repeat pump or valve failures
Pumps and thermostatic valves that keep seizing are usually being killed by what is in the water. Replacing the part without cleaning the system just starts the same clock again.
Worth saying
Not every cold radiator is sludge. Cold at the top is trapped air, and a radiator that is stone cold top to bottom is usually a stuck valve. Our blog post on why one radiator stays cold walks through diagnosing it yourself before you call anyone — including us.
How It Works
What actually happens on the day.
A typical domestic power flush takes four to eight hours, so most jobs are finished in a single day with the heating back on that evening.
01
We look at the water first
Before quoting anything we bleed a radiator and see what comes out, check the radiators for cold spots, and look at the age and type of system. If the water is reasonably clean, we will tell you a flush is not needed.
02
Pump connected, cleaner circulated
The flushing pump connects to the system and circulates a cleaning agent to break down the sludge and loosen scale from radiator panels and the heat exchanger.
03
Every radiator flushed individually
Each radiator is isolated and flushed in turn, with the flow reversed and the panel agitated to lift what has settled at the bottom. This is the part that actually shifts the sludge, and it is why the job scales with radiator count.
04
Refill, inhibitor, and a magnetic filter
The system is flushed until the water runs clear, refilled clean, and dosed with corrosion inhibitor. We will recommend a magnetic filter if there is not one fitted — it is what keeps the system clean afterwards.
05
Balanced, pressure checked, handed over
We balance the radiators so the heat is shared properly, check the system pressure, and run it up before we leave. Most people notice the difference the same evening.
What It Costs
Typical power flush prices in Edinburgh
Most Edinburgh homes land somewhere between £400 and £800. The number of radiators is the main driver — every one has to be isolated and flushed individually, so the job scales with the size of the house rather than with a flat call-out rate.
These are typical ranges, not a quote. What you will get from us is a fixed written price after we have seen the system — never an hourly rate that drifts once the vans are on the drive.
| System size | Typical range |
|---|---|
Up to 6 radiators Flats and small terraces. Usually a morning's work, sometimes into the early afternoon. | £350 – £500 |
7 – 10 radiators The commonest job — most 3-bed semis and terraces across Edinburgh and the Lothians. A full day. | £450 – £700 |
11+ radiators Larger and extended houses. Heavily silted systems at this size occasionally need a second visit. | £650 – £950 |
Magnetic filter fitted at the same time Optional, and nearly always worth it. Catches whatever the system generates from that point on. | £120 – £200 |
Heavily silted systems, old small-bore pipework, and awkward radiator positions all add time. Where a system is only lightly dirty we will often recommend a chemical clean and a magnetic filter instead, which costs considerably less and does the same job on that kind of water.
Why It Matters
Cheaper than the boiler you were about to be sold.
A fair number of the "you need a new boiler" quotes we see are really a silted system. The boiler is fine — it just cannot get heat through pipework that is half blocked.
Comfort
Rooms that heat up properly again
Clearing the sludge restores the flow through radiators that have been running at half capacity for years. The rooms that were always cold start behaving like the rest of the house.
Running cost
The boiler stops working so hard
A clogged system makes the boiler run longer and hotter to reach the same room temperature. Clean water and proper circulation let it condense the way it was designed to, which is where the efficiency lives.
Reliability
Fewer breakdowns, longer-lived parts
Sludge is what kills pumps, seizes valves, and blocks heat exchangers. Getting it out — and keeping it out with inhibitor and a filter — is the cheapest reliability work you can do on a heating system.
With A New Boiler
Never put a new boiler onto a dirty system.
It is the single most expensive shortcut in the trade. All the sludge sitting in the old radiators gets pulled straight into a brand new heat exchanger, and within a couple of winters you have the same cold spots and noises you paid to get rid of — except now it is a new boiler doing it.
Manufacturers know this, which is why nearly all of them require evidence that the system was cleaned and inhibited for the warranty to stand. A flush on install day is not an upsell; it is the condition on the ten-year warranty you are being sold.
See our boiler installation serviceThe heat exchanger is the vulnerable part
Modern condensing boilers have far narrower waterways than the cast-iron units they replaced. It takes much less debris to block one.
Warranty conditions are real
Worcester Bosch, Vaillant, Ideal, and Baxi all set out system-cleanliness requirements. A rejected warranty claim in year six costs far more than the flush did.
A magnetic filter goes on as standard
We fit one on every installation. It catches what the system produces from that day on, and it gets emptied at each annual service.
Where We Work
Power flushing across Edinburgh and the Lothians.
We are based in Danderhall, which puts most of the city and the three Lothians within half an hour. A lot of the housing stock round here — post-war semis, ex-mining terraces, and older tenement systems — is exactly the age where sludge has had time to build up.
Edinburgh
City-wide, including the tenement stock in the centre and the post-war semis out through Gilmerton, Liberton, and Corstorphine.
Midlothian
Our home patch — Danderhall, Dalkeith, Bonnyrigg, Loanhead, Penicuik, Newtongrange, and the old mining villages.
East Lothian
Musselburgh, Tranent, Prestonpans, Haddington, North Berwick, and the surrounding villages.
West Lothian
Livingston, Linlithgow, Bathgate, Broxburn, Kirkliston, and the wider west of the city.
Often booked together
A flush is frequently part of a wider job. If you are already looking at radiator changes, a controls upgrade, or a new boiler, we will scope them together and keep the price straightforward. See the central heating hub for everything else we cover.
Power Flushing FAQs
The questions we get asked about power flushing.
Straight answers on cost, how long it takes, when a chemical clean will do instead, and whether an older system is safe to flush.
What Comes Up Most
What a flush costs and what changes the price
How long the job takes and what happens on the day
Power flush versus a chemical clean
Whether an old system is safe to flush
Not sure whether you need one?
Tell us which radiators are cold, what the water looks like when you bleed one, and roughly how old the system is — we will tell you straight whether a flush is worth your money.
Read the full answer
Ready to book?
Get a fixed price for a power flush.
Free survey, a proper look at the water and the radiators, and a written price before anything starts. If your system does not need a flush, we will say so — that is a shorter conversation but an honest one.