What is a power flush and does my heating system need one?

A power flush is a high-velocity rinse of your central heating system that removes the sludge, rust and scale that build up over years of use. If your radiators have cold spots, your boiler is noisy, or you are installing a new boiler onto an old system, a power flush is usually recommended.

What happens during a power flush

• ◆An engineer connects a pump unit to your system - usually via the drain point or a radiator connection
• ◆A chemical cleaner is introduced and circulated at high speed, dislodging deposits from the pipework and radiators
• ◆Each radiator is flushed in turn until the water runs clear
• ◆A scale inhibitor and corrosion protector are added to the clean system before reconnection
• ◆A magnetic filter is fitted if one is not already present

How long does a power flush take?

A typical domestic system with 8 to 12 radiators takes four to six hours. Larger or more heavily contaminated systems may take a full day. We will give you a time estimate after looking at your system.

Signs your system needs a power flush

• ◆Multiple radiators with cold spots at the bottom
• ◆A boiler that makes banging, kettling or gurgling noises
• ◆You are fitting a new boiler and the existing system is more than 10 years old
• ◆Your boiler pressure drops frequently without an obvious external leak
• ◆Discoloured water when radiators are drained

Does a new boiler need a power flush?

Most boiler manufacturers recommend flushing the system before fitting a new boiler. Fitting a new boiler onto a contaminated system shortens the heat exchanger life and can void the warranty. Vaillant specifically require system cleansing as a condition of their extended warranty.

Power flush cost in Surrey

In Surrey and South London a power flush for a standard domestic system typically costs £300 to £500 depending on size and condition. This is a one-off cost that extends boiler life, improves efficiency and protects the warranty.

Frequently asked