By property size
Radiator count is the main driver, because each one is isolated and flushed individually. These are UK market rates as of mid-2026.
| Property | Radiators | Typical cost | Time |
|---|---|---|---|
| 2 bed flat | 4 | £350 | 1 day |
| 2 bed house | 6 | £450 | 1 day |
| 3 bed flat | 8 | £450 | 1 day |
| 3 bed house | 10 | £550 | 1 day |
| 4 bed flat | 11 | £600 | 1–2 days |
| 4 bed house | 15 | £800 | 1–2 days |
Some engineers price by the hour instead, around £50 an hour. On a straightforward job that lands in a similar place; on a bad one it does not, which is why a fixed quote after an inspection is usually the safer arrangement for you.
Why London costs more
Partly labour rates, but mostly the housing stock. London jobs run high because:
- Microbore pipework. 8mm and 10mm pipe from 1970s and 80s retrofits takes longer to clear and sometimes needs individual radiator tails disconnected.
- Converted flats. Access to pipework that runs through another property turns a one-day job into a negotiation.
- Period property. Cast iron radiators hold more water and more debris, and need lower pressure and more patience.
- Parking and access. Not glamorous, but a genuine cost on a van-based job in a controlled parking zone.
Expect the top of the range, or a little above it, in central and inner London. More on London specifically.
Price the alternatives first
| Job | Typical cost | When it is the right spend |
|---|---|---|
| Inhibitor level test | £0–£30 | Always. Cheapest diagnostic there is. |
| Bleed radiators | Free | Cold at the top. Do it yourself. |
| Valve free-up or replacement | £80–£150 | One radiator cold all over |
| System rebalance | £90–£180 | Far radiators lukewarm, post-extension |
| Inhibitor dose | £60–£100 | System healthy, inhibitor depleted |
| Magnetic filter fitted | £150–£250 | Almost always worth it on a steel system |
| Chemical flush | £150–£250 | Light to moderate sludging |
| Power flush | £350–£800 | Genuine, established sludging |
| New radiators | £150–£400 each fitted | Individual radiators beyond saving |
Working down that table in order is how you avoid spending £600 on a problem a £120 valve job would have fixed. The diagnostic checklist is here.
What should be in the price
A complete quote covers the flush itself, the cleaning chemicals, the correct dose of inhibitor afterwards, and a written record of what was done. A magnetic filter, if you do not already have one, is usually quoted separately at £150 to £250 — that is reasonable, as long as it is stated rather than discovered later.
Ask specifically whether the price is fixed or an estimate, and what happens if the system turns out worse than expected. The answer to that second question tells you a lot.
Will it save me money on heating?
Possibly, and nobody can tell you how much in advance. A badly restricted system running long cycles to heat cold rooms will use noticeably less gas once circulation is restored. A system with mild sludging will barely change.
The previous owner of this website advertised a flat 25% saving on fuel bills. That figure had no basis. Treat any specific percentage quoted to you before an engineer has seen your system the same way.
Common questions
How much does a power flush cost in 2026?
Between roughly £350 and £800 for most UK homes, driven mainly by the number of radiators — around £350 for a four-radiator flat and around £800 for a fifteen-radiator house. London and the South East sit at the upper end of that range.
How long does a power flush take?
Most domestic jobs are a single day. Larger properties with twelve or more radiators, or systems with microbore pipework or cast iron radiators, can run into a second day.
Is a power flush worth the money?
On a genuinely sludged system, yes — it is considerably cheaper than replacing radiators or a heat exchanger damaged by debris. On a system that is not actually sludged it is money wasted, which is why diagnosing the symptom properly first matters more than the price you are quoted.