System cleaning
It is the most over-sold job in heating. Most systems do not need it and we will say so. Here is how to tell whether yours is one of the ones that does.
Get my fixed priceWhat we are actually removing
Every steel radiator sheds a little iron into the water. Over twenty years that becomes a black sludge that settles in the bottom of panels and coats the heat exchanger.
The detail
A chemical flush is included with every boiler we fit, along with an inhibitor and a magnetic filter. For a system in reasonable condition, that combination is genuinely sufficient and anybody telling you otherwise is selling.
A power flush is a real job with a real machine and it costs us most of a day. We charge £265 for it and we suggest it when the answers you gave point that way — a regular or back boiler system, or an old circuit you are keeping. We never tick it for you.
Turn the heating on and let it run for twenty minutes. Then put a hand at the top of each radiator and at the bottom.
A power flush does not make a boiler more efficient in any way you will see on a bill. It protects the new heat exchanger and it gets the bottom third of your radiators working again. Both are worth having. Neither is a fuel saving, and we are not going to pretend otherwise.
Questions
Probably not. A chemical flush and an inhibitor are included with every boiler we fit and that is enough for the large majority of systems.
You need a power flush if radiators are cold at the bottom, if the water from a bleed valve runs black, if the system is over about twenty-five years old and has never been cleaned, or if you are keeping old radiators and fitting a new boiler onto them.
A chemical flush circulates a cleaner around the system using your own pump, then drains and refills it. It removes what is loose. It is included as standard.
A power flush connects a separate high-flow pump across the system and drives water hard in both directions, radiator by radiator, usually with a magnet on the return. It lifts what has settled. That is the £265 upgrade.
No — and it can reveal one. Old radiators are sometimes held together as much by the sludge inside them as by the metal. Clearing that occasionally exposes a pinhole that was already there.
We will tell you before we start if your system looks like that. It is rare, but it is honest to mention it.
The manufacturer's warranty usually requires the system to be cleaned and inhibited, and a magnetic filter fitted. We do all three as standard, so a straightforward system is compliant without a power flush.
If your system is genuinely dirty, skipping the flush risks the new heat exchanger. That is the one case where we will push you.
Three to five hours for a typical eight to ten radiator house, done on the same visit as your boiler. A very dirty system can take a full day.
Answer the quote questions and we will suggest a flush only if your answers actually warrant one.
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