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Central Heating Repair in London

Cold radiators with a hot boiler is a circulation problem, air, sludge, a stuck valve or a tired pump.

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No call-out feeNo night or weekend surchargeFixed price before we start12-month workmanship guarantee

The pattern of which radiators are cold tells most of the story before we even arrive.

Central heating repair in London: what the price includes

  • 01
    Diagnosis by pattern

    Cold at the top: air. Cold at the bottom: sludge. Cold at the far end: balancing or pump. Random: motorised valve. We read the system, then fix it.

  • 02
    Pumps and valves

    Circulators, zone valves and actuators carried for same-visit replacement.

  • 03
    Balancing done properly

    Whole-system balancing so the far bedroom finally warms without cooking the hallway.

  • 04
    Controls upgrades

    Failed programmers and thermostats replaced, smart controls fitted where they genuinely help.

  • 05
    Central heating service: the whole system, not just the boiler

    A boiler service looks after the boiler. A central heating service looks at everything the boiler feeds. We bleed the radiators and check each one heats evenly. We test the radiator valves, the pump and the motorised valves. We check the programmer and thermostats actually switch the heating on and off. We take a sample of the system water to see if sludge or corrosion is building up, and check the inhibitor level that protects the pipes. If you have a magnetic filter, we clean it. Then we balance the radiators so every room warms up. You get a short written note of what we found. It pairs well with an £89 gas boiler service on the same visit.

  • 06
    Diagnosed as a system, not as a symptom

    One cold radiator is a balancing or valve problem. Cold at the bottom across several is sludge. Cold at the top is air. Everything cold is a pump, a valve or a control. We establish which pattern yours is before anyone starts bleeding radiators at random.

Local conditions we work around

Cold spots at the bottom of London radiators are usually sludge; cold at the top is air; and a system that needs repressurising every few weeks has a leak rather than a habit. Hard water complicates all three, because scale in the boiler and deposits through the system reduce circulation and make balancing harder to hold. Where a system has been extended over decades, very common in London's subdivided housing, the original pipe sizing is frequently the real limit rather than any single faulty component.

Covered across London

Same price and the same guarantee in every area below. Each has its own page with the streets we cover.

HertfordHarlowBrentwoodUpminsterDartfordGravesendOrpingtonSevenoaksEpsomSuttonKingstonSurbiton All London areas →

Central heating repair in London, your questions

What is a central heating service?
It is a check of the whole heating system: radiators, valves, pump, controls and the water inside the pipes. It finds small problems, like sludge or a sticking valve, before they leave rooms cold. It is priced at our standard rate and agreed with you before we start.
Is a central heating service the same as a boiler service?
Not quite. A boiler service cleans and tests the boiler itself. A central heating service covers the rest of the system. If radiators are patchy or some rooms never warm up, the heating service is the one that helps.
Some radiators are hot and some cold, why?
If the cold ones are furthest from the boiler, the system needs balancing or the pump is tiring. If they're cold at the bottom, sludge has settled, that's a flush. Top-cold is just air: bleed them first, it's free.
What does a typical circulation repair cost?
Standard rate card: £110 first hour, most valve/pump swaps completed within it plus parts. Balancing a whole system is usually one visit.
Is banging or kettling serious?
Kettling (a boiling-kettle rumble) means scale on the heat exchanger working as insulation, it shortens boiler life meaningfully. A cleanse now beats an exchanger later.
Why is one radiator always cold?
Cold at the top means air, and bleeding it fixes it. Cold at the bottom means sludge sitting in the panel and needs flushing. Cold all over usually means a seized thermostatic valve pin, which is a five-minute fix once identified.
My upstairs is hot and downstairs is cold.
That is a balancing problem, and it is very common after a boiler change. The lockshield valves need setting so flow is shared correctly rather than taking the path of least resistance. It is an adjustment, not a repair, and no parts are involved.
Do I need a magnetic filter?
In London we would say yes on any system over ten years old. It catches the iron oxide that causes cold spots and eventually kills pumps and heat exchangers, and it is cheap next to what it prevents. In soft-water areas it matters more than a scale reducer.

Central Heating Repair? Call.

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