Get quotes to powerflush a central heating system

HaMuch is Excellent
By Emily Rivers
Last updated 12th August 2022

If you have noticed that your radiators take a long time to heat up, or are riddled with cold spots then it might be time for your central heating system to be powerflushed.

Common symptoms of needing a powerflush include;

  • Noisey banging boiler called “kettling”
  • Boiler cutting out due to slow circulation
  • Cold spots at the bottom of a radiator clogged up from sludge
  • Cold spots at the top of a radiator from air
  • Radiators very slow to heat or stone cold from blocked circulation
  • Hot water in taps from a combi boiler fluctuating from hot to cold

What is powerflushing?

Powerflushing is the use of chemicals and high flow rate to break down the build-up of rust debris, also known as black sludge, and penetrate through stubborn blockages in the central heating system. Powerflushing involves using a powerflush machine. This machine has a high flow rate and is able to reverse the flow of the system, to push the water in both directions to really force out stubborn debris. 

This vigorous flow coupled with the chemicals can remove the iron oxide sludge debris out of the pipework and radiators. The powerflush engineer will also create a back and forth motion of water with his machine to agitate the inside of the pipework to help loosen any build-up of sludge (they may also agitate the outside of the radiators depending on the fragility of the system). Where some people think that fitting a magnet filter near the boiler to catch debris is enough, this will only catch loose debris travelling around the system with the flow of water but will not remove any build-up of sludge trapped in radiators or pipework, only the power flush will do that.

Cost to powerflush a central heating system

Why do British Gas say I need a power flush?

If you have a homecare agreement with British Gas and they maintain your boiler, before British Gas replaces any parts on the central heating system, they want the new part being plumbed into a clean sludge-free system to avoid the new part being destroyed by debris. This is why British Gas usually insists on a powerflush before they replace parts. The good news is even when on a British Gas service contract, check with them but you are usually completely in your rights to shop around for the best quote and get the powerflush completed by someone else, as long as you have an invoice or some form of documentation to prove that you have paid for a powerflush on your central heating system.

System flush vs power flush vs chemical flush

Sometimes it can get tricky understanding what it is that your system requires to get it back to optimal working performance. Especially when tradespeople might use different jargon to advise on the same course of action. 

If a heating engineer has told you to get a system flush and you got a second opinion from another heating engineer mentioning a power flush… yes, they are both referring to the same chemical clean.

A power flush, also referred to as a system flush or a system power flush, just means cleaning out the entire central heating circuit with the use of the powerflush machine and chemicals. Do not bother with doing a partial flush, paying someone to come in and not flush out all of the radiators because once the circuit is back on in winter, the sludge debris that was sitting in a different part of pipework will just contaminate the cleaned out radiators.

When told you need a chemical flush, best to get clarity from the gas engineer, are they referring to a powerflush, or are they meaning using chemicals to dose the system, travel around by turning the heating on, and then draining down the system. This can work if the system is not badly blocked. If you are already paying out a lot of money, then best to just do a more intense version with better results and powerflush. There is no draining down for a powerflush, but rather keeping the system pressurised and pushing out the dirty water while constantly topping up with clean water, this way is to prevent any further blockages in elbows of pipework that draining down can cause.

How much will it cost to powerflush?

The total cost of the powerflush can be from a man-in-van offering to do it for just a few hours labour and the cost of hiring a powerflushing machine (from £300) to paying a specialised company, who own the equipment and more familiar with different scenarios they may come across on different heating systems (from £400). Most often, a powerflush is completed in a day. Smaller systems require just half of the day. Time taken to powerflush will depend on how often the engineer carries out a powerflush, as someone hiring the equipment and not too familiar or confident with its operating, may take longer than someone who does this daily.

Other factors affecting the cost are;

  • how many floors are involved in your property as some companies will charge per floor
  • how many radiators / towel rails / loops of underfloor heating are in the home
  • what size pump you might have (large homes might run on a commercial sized pump)
  • If the system requires a first visit of a pre-treatment of the cleaning chemicals before the day of power flushing

How much labour costs to power flush

Per

Average total labour cost

Powerflush 7 radiators

Per day

£400 

Powerflush 12 radiators

Per day

£560 

Pre-treat a blocked system and then powerflush 10 radiators

Per day

£620

Powerflush 12 radiators and change a circulatory pump

Per day

£660

Is my system too old to powerflush?

A big concern is whether a system is too old to handle a powerflush or if the powerflush will result in leaks, with high pressure bursting through old pipework. As long as your central heating system has water running through the boiler, and a circuit of pipework, it is suitable to be powerflushed.

Powerflush cleaner chemicals are mostly non-acidic therefore are safe and do not cause any damage to copper or plastic pipes (there is an acid option for a more vigorous clean and heating engineers will then neutralise the system with neutralising crystals afterwards but if your system is fragile they will not use this option).

A boiler, for safety reasons, is designed to handle water pressure of up to 4.5 bar. The maximum pressure of a power flushing pump will never exceed much more than 2 bar of pressure, therefore it is not putting the central heating system under any unnecessary stress. Worst case, is removing the sludge, the sludge might be eating its way through radiators and the debris acting as a cork, so once the debris has been removed, this may expose existing pin-holes in radiators. These would eventually become apparent, with or without a powerflush, as eventually the rust eating through would be too big a hole to ‘self-seal’.

How often should I get a powerflush?

It is suggested that a powerflush is carried out on a system every 5 - 6 years. This will prolong the life of the boiler. During this time span, it means that any build up of sludge that starts after an initial powerflush will be flushed out again to avoid solid blockages forming over the years. 

A powerflush is also needed when a new boiler is being installed. A new boiler’s components, like a heat exchanger, diverter valve, pump… will be protected by not having  sludge debris running through the boiler. If a brand new boiler is installed into a dirty system, within two years you might need to replace a burnt-out pump or damaged heat exchanger, ruined from sludge.

Systems that are prone to debris, perhaps badly plumbed in pipework that draws in air, microbore systems where the pipework is so thin that it only takes a tiny bit of debris to block the system or single pipe systems where there is no real control of where to send the chemical water during the powerflush but more on only where the system will allow the flow, these types of systems may need a powerflush more frequently than standard systems to maintain the boilers and keep heat reaching radiators. Microbore systems can be effectively powerflushed but might just need a bit more attention and time of the day from the heating engineer carrying out the flush. For best results with microbore, single pipe or badly blocked systems is to actually put the chemical cleaner in a few weeks before the intended powerflush to really give the chemicals a chance to circulate and start breaking down debris blockages.

However often your system is powerflushed, it is good practice to yearly top the system up with a corrosion inhibitor. This will not prevent corrosion but will slow down the pace of it re-building.


Estimates for common heating engineer jobs;

Rates for other trades

Powerflush cost in the UK
Powerflush cost in the UK (excluding VAT or callout charges)
Location in UKPowerflush cost
Powerflush near Aberdeen£580
Powerflush near Amber Valley£488
Powerflush near Angus£540
Powerflush near Arun£552
Powerflush near Ashfield£482
Powerflush near Aylesbury Vale£554
Powerflush near Barnsley£470
Powerflush near Basildon£528
Powerflush near Basingstoke & Deane£570
Powerflush near Bassetlaw£492
Powerflush near Bath & North East Somerset£534
Powerflush near Bedford£570
Powerflush near Belfast£456
Powerflush near Birmingham£476
Powerflush near Blackburn£468
Powerflush near Blackpool£498
Powerflush near Bolton£496
Powerflush near Bournemouth£546
Powerflush near Bracknell Forest£588
Powerflush near Bradford£472
Powerflush near Braintree£524
Powerflush near Breckland£484
Powerflush near Bridgend£460
Powerflush near Brighton£540
Powerflush near Bristol£518
Powerflush near Broadland£538
Powerflush near Broxtowe£478
Powerflush near Bury£490
Powerflush near Caerphilly£464
Powerflush near Calderdale£464
Powerflush near Cambridge£556
Powerflush near Canterbury£506
Powerflush near Cardiff£476
Powerflush near Carmarthenshire£400
Powerflush near Charnwood£454
Powerflush near Chelmsford£520
Powerflush near Cheltenham£620
Powerflush near Cherwell£576
Powerflush near Chester£456
Powerflush near Colchester£512
Powerflush near Conway£434
Powerflush near Coventry£470
Powerflush near Crewe & Nantwich£482
Powerflush near Dacorum£572
Powerflush near Derby£458
Powerflush near Doncaster£496
Powerflush near Dover£476
Powerflush near Dudley£478
Powerflush near Dumfries & Galloway£496
Powerflush near Dundee£544
Powerflush near East Ayrshire£426
Powerflush near East Devon£490
Powerflush near East Dunbartonshire£568
Powerflush near East Hampshire£550
Powerflush near East Hertfordshire£566
Powerflush near East Lindsey£440
Powerflush near East Riding£418
Powerflush near Eastleigh£562
Powerflush near Edinburgh£534
Powerflush near Elmbridge£588
Powerflush near Epping Forest£588
Powerflush near Erewash£462
Powerflush near Exeter£508
Powerflush near Falkirk£564
Powerflush near Fife£538
Powerflush near Flintshire£450
Powerflush near Gateshead£520
Powerflush near Gedling£472
Powerflush near Glasgow£560
Powerflush near Gloucester£644
Powerflush near Guildford£594
Powerflush near Gwynedd£448
Powerflush near Halton£484
Powerflush near Harrogate£460
Powerflush near Havant & Waterloo£532
Powerflush near Highland£640
Powerflush near Horsham£544
Powerflush near Huntingdonshire£558
Powerflush near Ipswich£620
Powerflush near Isle of Wight£526
Powerflush near Kings Lynn & West Norfolk£520
Powerflush near Kingston-upon-Hull£420
Powerflush near Kirklees£470
Powerflush near Knowsley£478
Powerflush near Lancaster£526
Powerflush near Leeds£464
Powerflush near Leicester£456
Powerflush near Lisburn£444
Powerflush near Liverpool£474
Powerflush near London£582
Powerflush near Luton£578
Powerflush near Macclesfield£488
Powerflush near Maidstone£520
Powerflush near Manchester£486
Powerflush near Mid Bedfordshire£558
Powerflush near Mid Sussex£556
Powerflush near Middlesbrough£508
Powerflush near Milton Keynes£560
Powerflush near Neath Port Talbot£476
Powerflush near New Forest£552
Powerflush near Newbury£560
Powerflush near Newcastle-under-Lyme£474
Powerflush near Newcastle-upon-Tyne£522
Powerflush near Newport£480
Powerflush near North Ayrshire£466
Powerflush near North East Lincolnshire£490
Powerflush near North Hertfordshire£568
Powerflush near North Lanarkshire£564
Powerflush near North Lincolnshire£444
Powerflush near North Somerset£510
Powerflush near North Tyneside£516
Powerflush near North Wiltshire£608
Powerflush near Northampton£552
Powerflush near Norwich£526
Powerflush near Nottingham£464
Powerflush near Nuneaton & Bedworth£468
Powerflush near Oldham£490
Powerflush near Oxford£578
Powerflush near Pembrokeshire£402
Powerflush near Perth & Kinross£542
Powerflush near Peterborough£570
Powerflush near Plymouth£492
Powerflush near Poole£544
Powerflush near Portsmouth£530
Powerflush near Powys£600
Powerflush near Preston£492
Powerflush near Reading£598
Powerflush near Redcar & Cleveland£498
Powerflush near Reigate & Banstead£582
Powerflush near Renfrewshire£546
Powerflush near Rhondda, Cynon, Taff£460
Powerflush near Rochdale£494
Powerflush near Rochester-upon-Medway£560
Powerflush near Rotherham£482
Powerflush near Salford£486
Powerflush near Salisbury£514
Powerflush near Sandwell£474
Powerflush near Scarborough£528
Powerflush near Scottish Borders£760
Powerflush near Sefton£480
Powerflush near Sevenoaks£542
Powerflush near Sheffield£490
Powerflush near Slough£588
Powerflush near Solihull£474
Powerflush near South Ayrshire£472
Powerflush near South Bedfordshire£570
Powerflush near South Cambridgeshire£534
Powerflush near South Gloucestershire£524
Powerflush near South Kesteven£540
Powerflush near South Lanarkshire£532
Powerflush near South Oxfordshire£580
Powerflush near South Somerset£524
Powerflush near South Tyneside£520
Powerflush near Southampton£558
Powerflush near Southend-on-Sea£510
Powerflush near St Albans£582
Powerflush near St Helens£476
Powerflush near Stafford£492
Powerflush near Stockport£492
Powerflush near Stockton-on-Tees£510
Powerflush near Stoke-on-Trent£472
Powerflush near Stratford-on-Avon£490
Powerflush near Stroud£586
Powerflush near Suffolk Coastal£668
Powerflush near Sunderland£520
Powerflush near Swale£502
Powerflush near Swansea£464
Powerflush near Tameside£488
Powerflush near Teignbridge£500
Powerflush near Tendring£582
Powerflush near Test Valley£536
Powerflush near Thamesdown£622
Powerflush near Thanet£524
Powerflush near The Wrekin£500
Powerflush near Thurrock£536
Powerflush near Torbay£496
Powerflush near Trafford£494
Powerflush near Vale of Glamorgan£472
Powerflush near Vale of White Horse£590
Powerflush near Vale Royal£446
Powerflush near Wakefield£472
Powerflush near Walsall£476
Powerflush near Warrington£492
Powerflush near Warwick£482
Powerflush near Waveney£506
Powerflush near Waverley£584
Powerflush near Wealden£536
Powerflush near West Lancashire£482
Powerflush near West Lothian£558
Powerflush near West Wiltshire£608
Powerflush near Wigan£480
Powerflush near Windsor & Maidenhead£588
Powerflush near Wirral£470
Powerflush near Wokingham£586
Powerflush near Wolverhampton£476
Powerflush near Wrexham Maelor£536
Powerflush near Wychavon£530
Powerflush near Wycombe£606
Powerflush near York£454