Welcome to Quotation Check – Your guide to building costs in the UK. This page is part of our series into costs/prices charged by gas engineers and plumbers. You can see all of our prices here. We last updated this page on the
. This page tries to answer the question: How much does it cost to power flush a central heating system?
Power flushing is a technique used to clear sludge from central heating system pipes, radiators, coils and heat exchangers. These are areas where scale and corrosion can collect, the symptoms are usually:
- Cold spots on radiators, even after bleeding
- Takes a long time for radiators to warm up
- Noisy boiler
- Radiators needing regular bleeding
- Inefficient central heating system
Once a power flush is complete, you can expect the following benefits:
- Pipes and radiators will get hotter quicker
- More cost efficient system
- Less stress on the boiler
- Increased life of the boiler
- Heat will be distributed more evenly throughout the home
Central heating boilers can fail early if there is excessive sludge in the system, modern condensing boilers are much more sensitive so it’s recommended to have a full system flush before installing a new boiler. There is no point in paying for an expensive piece of kit that may fail early because of excessive sludge build up in the system!
You should also check the guarantee on any new boiler as most manufacturers will not accept a claim if the system hasn’t been recently power flushed.
Cost to Power Flush Central Heating Radiators and Pipes
How much does it cost to power flush a heating system? What is a fair price to pay and will you save money in the long-term?
It wasn’t difficult to gather a large pool of quotes from various plumbers and heating engineers up and down the country, many of our chosen businesses were happy to provide a price/cost without visiting the property, some such as British Gas insisted on a visit.
We would advise homeowners to have this work carried out if a new boiler is being installed and/or if the system hasn’t been cleaned for a long time. Once complete, the system should run more efficiently, saving you money. Although it is impossible to predict a return on investment.
Our quotes were all for 2-bed houses with a boiler less than 20 years old.
As you can see from our table below, the average cost of a powerflush is £410.00. This is based on our research into quotes from companies based in the United Kingdom.
|Location||Small Business /Trader||Larger Business (5+ employees)|
|Need a Custom Price? >|
|South, SW and Midlands||£400.00||£500.00|
|Outer Region and North||£325.00||£500.00|
Get a Personalised Power Flushing Quote Here
Your next step? Get a customised power flushing price (only takes a few minutes)
- Send in details of your heating system
- Check ratings from previous customers
- Over 3million jobs completed to date
- 500,000 reviews
- It’s a FREE service
- No commitment
Just fill in the form now to start the process.
See What Other Prices We Discovered:
Can You Rely on Our Price Guides?
Our prices are based on real quotations given to us by plumbers and heating engineers in the United Kingdom.
We then calculate an average cost and publish the figures on this site.
Our hope is that you can avoid traders who overcharge and budget your finances accordingly.
Don’t forget that every project is different and the quotes we gather may be different to the ones you are given. If you need a firm price, we suggest you contact three local plumbers and compare prices yourself.
See exactly how we gather quotes from tradespeople here.
How Trustworthy Are Plumbers in The UK?
Check out the results and cast your own vote. See how trustworthy plumbers are compared to other tradespeople.
What You Get For Your Money – How Power Flushing Works
During the initial consultation, your chosen contractor should explain the work involved and the expected cost savings.
Before commencing with the actual work your trades-person should start the boiler and check all the radiators for cold spots, ideally taking the temperature of each rad. A sample of the water should also be taken – for comparison.
Once all radiator valves have been removed or opened, dust sheets placed over carpets etc, the power flushing machine can be connected.
The first flush will involve a chemical power flush of the entire system including a reverse flow, this usually takes around 20 minutes. Each individual rad is then isolated and flushed, starting with the coldest rads. A rubber mallet can be used to loosen up any scale/sludge. This process is then duplicated across all the radiators.
A second flush takes place across all radiators individually, the fluid is reversed periodically until the water is clear and free from sludge. This is repeated with all radiators.
A final full system flush is then undertaken, this is continued until the water being dumped is clear and free of sludge.
Finally, an inhibitor is added to the water and circulated through the system for 15 minutes. A sample is then taken and tested, more inhibitor can be added if required. The TRVs (radiator valves are then refitted and set to their original settings)
Rough Checklist for Power Flushing Radiators/Central Heating System
- Record temperature of radiators (so we know which are heavily clogged)
- Record TRV settings on each radiator
- Take water sample
- Open all valves and remove TRVs
- Bridge any valves or equipment that may prevent reverse flow i.e pump
- Isolate boiler
- Take precautions to protect carpets etc
- Connect power flushing unit
- Carry out primary and secondary flushes dislodge stubborn sludge with rubber mallet or vibrating tool
- Remove any stubborn radiators and manually clean with hose. refit rads.
- Take temperature of individual rads and compare to original radiators
- Test water
- Add inhibitor (also neutralizer depending on system) and test
- Re install TRV’s and any other valves and apply original settings
How Long Does a Power Flush Take?
This depends on how may radiators there are and also how much sludge is inside them. For a typical two bed house assume 4-6 hours. If your trades-person has to remove lots of radiators and manually flush each one with a power washer and then refit them then assume longer!
Q: Do radiators need to be removed?
A: In some cases, compacted sludge can only be removed by removing the rads and manually cleaning them with a powered pressure washer/hose.
Q: Instead of having the system flushed can I not just install a permanent magnetic filter?
A: Sludge caught in the rads will not circulate so won’t be caught in a magnetic filter unless a power flush is completed. These filters only catch loose sludge, not sludge which is compacted.
Q: I have had my rads repeatedly flushed but they keep blocking up with sludge, what gives?
A: If your heating system is allowing oxygen into the pipework, this will accelerate the corrosion of the pipes/rads leading to frequent and excess development of rustic sludge. We suggest you have your heating system checked by a qualified engineer before you flush the system again.
Q: How often should I have the system power flushed
A: If done correctly you shouldn’t need to have the system flushed for 10+ years but if the rads/pipework are corroding and producing fresh sludge then it need to be flushed sooner. Having the correct levels of inhibitor in the system and having this checked/topped up yearly will help. Make sure you make a note of which brand of inhibitor has been used, otherwise testing will be inconclusive (some installers leave the empty bottle behind)
Q: Can all types of central heating systems be flushed?
A: Yes, all types of heating systems can be flushed.
Q: Are TRV (rad valves) an issue?
A: No, the pins can get stuck as a result of the sludge but this is easily checked and remedied.
Q: I have received a quote for £150, is this a fair price/cost?
A: For this price we would not expect a complete and thorough power flush, although water may run clear after a power flush it may be because the water is flowing over compacted sludge. Removing this compacted material takes time as it often involves tapping the rads or removing them and manually cleaning them. We would suggest £300-£450 for a two bed house as a guide price, depending on location. Prices do vary obviously, some smaller firms may charge below £300 while large companies like British Gas have been known to charge well above £600.
Q: Should I have the central heating system drained and refilled every year?
A: No. This will only add oxygen and other impurities to the water, this will accelerate the corrosion.
Q: What is the sludge actually made from?
A: It is mostly rust that corrodes from the metal pipes and radiators, but also contains contaminants from the water.
This video is publicly available via David Gaylard’s YouTube channel.
Compare Quotes For Your Plumbing Job Today
We are affiliated with Rated People – the UK’s leading website for sourcing plumbing quotes.
You can obtain written quotations from reputable and qualified plumbers, read their customer reviews and make an informed choice without obligation.
Rated People have appeared in:
- Keep an eye out for the Trustmark logo, displayed next to traders who are part of this scheme
- Rated People helps you avoid cowboys – customer feedback is published on the site
- Avoid time wasters – only those plumbers actively seeking work are listed
- Over 3million jobs posted – all by customers just like you
- 500,000 reviews and ratings left by genuine customers