How do I know if my system needs a power flush?

The reliable signs are cold at the bottom of radiators rather than the top, black water when you bleed one, a magnetic filter that refills within weeks of cleaning, and a boiler kettling or short cycling. One cold room with everything else fine is usually balancing or a valve, and a flush will not change it.

Will a power flush damage old pipework?

It is a high volume, low pressure process, and the pressure used is below what the system runs at in normal operation, which is the opposite of what the name suggests. The real risk is not pressure but disturbance: in a system already leaking, or with corroded radiators thinned from the inside, the fix for the leak comes first.

How long does it take?

Most of a day for a typical London house. Heavier contamination, a lot of radiators or a large property takes longer, because each radiator is isolated and agitated individually rather than the machine simply being left running on the circuit. We give you a realistic figure after seeing the system.

Is a chemical flush the same thing?

No. A chemical flush circulates a cleaner using the system's own pump and then drains it, which helps a mildly dirty system and is much cheaper. A power flush uses an external pump at high flow with reversals and individual radiator agitation, which is what shifts settled magnetite. The choice depends on how bad it actually is.

Will it fix my cold radiator?

If that radiator is cold along the bottom and the water out of it is black, very likely. If it is cold at the top, bleeding it is the answer. If it is cold all over while the pipes at the valves are hot, the valve is the problem. A flush fixes a sludge problem and nothing else, which is why the diagnosis comes before the quote.

Power Flushing
In London

Power flushing is sold far more often than it is needed. So this page starts with how to tell, because a flush on a system that is not sludged is several hundred pounds that changes nothing.

Sludge tested for before selling a flush
Told when a flush is the wrong fix
Filter fitted to keep it clean

Quick Quote Online Call 07401 062636

Excellent5.07 reviews

Reviews

What Customers Say About The Work

Excellent5.07 reviews

Really pleased with the service from Drain Plumb Contractors. The work was carried out professionally, everything was explained clearly, and the area was left clean and tidy afterwards. Would happily recommend them to anyone looking for a reliable plumber.
Google reviewer
Had an urgent plumbing problem and needed someone to help. Drain Plumb Contractors were professional and helpful throughout, and the issue was dealt with efficiently. A stressful situation made much easier. Thank you for the great service.
Google reviewer
Great service for a drainage problem that needed sorting. The team were helpful, explained what needed doing and handled the job professionally. Everything was left in good order afterwards. I'd definitely consider using Drain Plumb Contractors again.
Google reviewer
Really good experience from start to finish. Friendly, professional and easy to deal with, with clear communication throughout. It's reassuring to find tradespeople who take the time to explain the work and treat your property with care. Would recommend.
Google reviewer
Very happy with the service provided. Communication was clear, the work was explained before getting started, and the whole process was straightforward. Good workmanship and a professional approach. I'd be happy to use Drain Plumb Contractors for future work.
Google reviewer
Very pleased with the plumbing work. The job was completed to a good standard, and the attention to detail was appreciated. Everything was left neat and tidy, and the service was professional throughout. Would happily recommend them.
Google reviewer
I've been very happy with the service from Drain Plumb Contractors. They're professional, approachable and take the time to explain things properly. It's good to have a company you can contact when plumbing or drainage work is needed. Would recommend them to others.
Google reviewer

Prove The Sludge
Cold radiator bottoms and a dark water sample are tested first.
Wrong Purchase Cases
If balancing or a valve fixes it, you are told before paying for a flush.
What The Machine Does
High flow and cleaning chemicals, radiator by radiator.
Keeping It Clean
Inhibitor and a magnetic filter so the sludge does not return.

A jar of black sludged system water beside a magnetic filter canister on a dust sheet

Power Flushing

The tests that say yes or no

Cold spots at the bottom of radiators rather than the top: sludge, not air. Several radiators cold at the far end of the circuit with the near ones scalding: that might be sludge or it might be balancing, and the two are told apart by setting the lockshields and seeing what changes. Black water out of a bled radiator: iron oxide, and plenty of it. A boiler short cycling or making kettling noises: restricted flow. A magnetic filter that fills within weeks of being cleaned: an active, circulating problem.

If none of those is true and the complaint is one cold room, a flush is not the answer and we will say so.

Power Flushing is priced after the job has been seen, anywhere in the areas we cover. Send the postcode and a few lines about what it is doing when you contact us, and the answer comes back in writing.

Quick Quote Online

The Job In Detail

What Power Flushing Involves

What the machine does

A pump is connected across the system, usually at a radiator or the circulating pump position, and pushes a high volume of water at low pressure through the circuit, reversing the direction repeatedly. Chemicals go in to break the magnetite loose, each radiator is isolated in turn and agitated so the debris lifts rather than being pushed round, and a magnet in the flow catches what comes out. At the end the system is flushed to clear water, neutralised, refilled and dosed with inhibitor.

High volume and low pressure is the important part. The pressure is lower than the system normally runs at, which is why it does not blow weak joints, contrary to the common worry.

How long, and what we record

A typical London house takes most of a day, and more with a lot of radiators or heavy contamination. What gets recorded is the water clarity at the start and the finish, the inhibitor added, and the before and after flow temperature difference across the boiler, which is the measurement that actually demonstrates it worked.

When a flush is the wrong purchase

Microbore pipework that is already blocked solid will not clear, and in bad cases needs replacing. A system with a leak should not be flushed until the leak is fixed, because fresh water and air are what made the sludge in the first place. An unbalanced system needs balancing. And a single cold radiator with a seized valve needs that valve. In all four cases we would rather tell you than take the booking.

Quick Quote Online

How It Works

How A Power Flushing Job Runs

Describe the radiators

Which are cold at the bottom, and how old the system is.

Tested first

Water sample and temperatures checked to confirm sludge is the cause.

Flush priced

Number of radiators, filter and inhibitor, all in writing.

Radiators cold at the bottom? Tell us how many and how old the system is.

Check My System

FAQs

Power Flushing Questions

The reliable signs are cold at the bottom of radiators rather than the top, black water when you bleed one, a magnetic filter that refills within weeks of cleaning, and a boiler kettling or short cycling. One cold room with everything else fine is usually balancing or a valve, and a flush will not change it.
It is a high volume, low pressure process, and the pressure used is below what the system runs at in normal operation, which is the opposite of what the name suggests. The real risk is not pressure but disturbance: in a system already leaking, or with corroded radiators thinned from the inside, the fix for the leak comes first.
Most of a day for a typical London house. Heavier contamination, a lot of radiators or a large property takes longer, because each radiator is isolated and agitated individually rather than the machine simply being left running on the circuit. We give you a realistic figure after seeing the system.
No. A chemical flush circulates a cleaner using the system's own pump and then drains it, which helps a mildly dirty system and is much cheaper. A power flush uses an external pump at high flow with reversals and individual radiator agitation, which is what shifts settled magnetite. The choice depends on how bad it actually is.
If that radiator is cold along the bottom and the water out of it is black, very likely. If it is cold at the top, bleeding it is the answer. If it is cold all over while the pipes at the valves are hot, the valve is the problem. A flush fixes a sludge problem and nothing else, which is why the diagnosis comes before the quote.

Power Flushing

Is It Sludge?
Let Us Check

How many radiators, which ones are cold and where, and roughly how old the system is. We will tell you if a flush is not the answer.

Excellent5.07 reviews

07401 062636

info@drainplumbcontractors.co.uk

Greater London

This form is secure. Your details are only used to send your quote, never shared.

Power Flushing
In London

Reviews

What Customers Say About The Work

Prove The Sludge

Wrong Purchase Cases

What The Machine Does

Keeping It Clean

Power Flushing

The tests that say yes or no

The Job In Detail