A boiler repair starts by identifying why the boiler or heating system is no longer operating correctly, rather than simply replacing parts based on the symptoms.
We diagnose and repair common problems affecting combi, system and heat-only gas boilers, including:
- no heating or no hot water
- boiler lockouts and fault codes
- leaking boilers
- repeated pressure loss
- ignition and flame faults
- circulation and pump problems
- diverter valve and control faults
- unusual boiler noises
- thermostat, programmer and sensor faults
- breakdowns affecting the wider central-heating system
Where possible, the fault can be repaired during the visit. If specialist parts are required, we will explain what has failed, what is needed and the likely cost before additional work proceeds.
Gas Safe Boiler Repair by Qualified Heating Engineers
A boiler can stop working for many different reasons, and the symptoms do not always identify the failed component.
For example, a boiler that repeatedly loses pressure could have an external heating-system leak, a pressure-relief issue, an expansion-vessel fault or another internal problem. A boiler displaying an ignition fault may be responding to a gas-supply problem, ignition component failure, flame-detection issue or another safety-related condition.
That is why our repair process starts with fault diagnosis.
Our engineer assesses the boiler, its controls and the relevant parts of the heating system before recommending replacement components or further work. The objective is to establish the cause of the fault, restore safe operation where repair is appropriate and give you enough information to make an informed decision.
Why Professional Boiler Diagnosis Matters
Gas Safe Registered Engineers
Gas boiler work is carried out by appropriately qualified Gas Safe registered engineers.
Diagnosis Before Parts
We investigate the fault before recommending component replacement wherever practicable.
Clear Repair Recommendations
You are told what we have found, what work is recommended and whether further parts or labour are required.
Written Service Reports
Repair and diagnostic visits can be documented for your maintenance, landlord or property-management records.
What Counts as an Emergency Boiler Repair?
Not every boiler fault is a gas emergency, but some breakdowns need faster attention because they leave a property without essential heating or hot water, create an active water leak or could lead to further damage.
Examples of faults that commonly justify an urgent boiler-repair booking include a complete loss of heating during cold weather, no hot water, an active boiler leak, repeated lockouts, rapidly falling system pressure, failure to ignite or a boiler that cannot be restored to normal operation.
The level of urgency can also depend on the property. A heating failure may require greater priority where there are elderly people, young children, vulnerable occupants, tenants or premises where heating and hot water are operationally important.
Gas Smell or Carbon Monoxide Is Different
If you smell gas, suspect a gas escape or a carbon-monoxide alarm sounds, do not wait for an ordinary boiler-repair appointment.
Stop using the appliance, avoid naked flames and operating electrical switches, ventilate the property where it is safe to do so and call the National Gas Emergency Service on 0800 111 999.
Common Boiler Faults We Diagnose and Repair
No Heating or No Hot Water
A complete or partial loss of heating or domestic hot water is one of the most common reasons for a boiler call-out. Possible causes range from controls, sensors and valves to circulation, ignition or internal boiler faults. On combi boilers, telling us whether heating, hot water or both have stopped working helps narrow the initial diagnosis.
Boiler Losing Pressure
If boiler pressure drops occasionally, the cause may differ from a system that needs topping up every few days. Persistent pressure loss should be investigated because it can be associated with a leak, expansion-vessel problem, pressure-relief valve or another heating-system fault. See our boiler pressure guide for more detail.
Boiler Leaking Water
Water dripping from beneath the boiler, around pipework or from an internal component should not simply be ignored. Leaks can originate from seals, valves, pipe connections, heat-exchanger components or excess system pressure. See our guide to water dripping from a boiler for more information.
Boiler Lockout or Fault Code
Modern boilers monitor their own operation and may shut down when a safety or performance problem is detected. The code displayed is useful diagnostic information, but does not always identify the exact failed component. Record it and provide it when booking. For Vaillant owners, see our Vaillant boiler problems and fault codes guide.
Ignition and Flame Faults
A boiler that clicks but will not ignite, repeatedly attempts to start, loses its flame or enters lockout needs proper diagnosis. Gas-supply, ignition, electrode, flame-detection, valve and combustion-related faults should only be assessed by an appropriately qualified Gas Safe registered engineer.
Pump and Circulation Problems
Poor circulation can result in overheating, noise, cold radiators, uneven heating or boiler shutdown. A failed or sticking pump is one possible cause, but restrictions, air, valves, controls and system condition may produce similar symptoms.
Diverter Valve and Hot-Water Problems
On combi boilers, the diverter valve directs heat between the central-heating circuit and domestic hot water. A valve that is sticking or failing can cause heating to work with no hot water, hot water to work while radiators stay cold, or inconsistent temperatures.
PCB, Sensor and Control Faults
The printed circuit board coordinates many boiler functions, while temperature sensors, thermostats and other controls provide the information the boiler needs to operate correctly. Because several components can produce similar symptoms, electrical and control faults should be tested rather than diagnosed from a fault code alone.
Noisy Boiler
Banging, kettling, humming, whistling or unusual vibration can indicate circulation issues, scale, air, pump problems or other faults. See our noisy boiler guide for the common causes and when professional investigation is appropriate.
Central-Heating System Faults
Sometimes the boiler itself is functioning but the wider system is preventing heat from reaching parts of the property. Radiator cold spots, circulation problems, hidden heating leaks, sludge and restrictions may require central-heating diagnosis, leak detection or power flushing rather than simply replacing boiler components.
Boiler Types We Repair
Our heating engineers work on many commonly installed gas boiler configurations, including:
- combi boilers, which provide heating and hot water directly from the boiler
- system boilers, typically connected to a separate hot-water cylinder
- heat-only or regular boilers, used with separate hot-water storage and associated system components
- modern condensing gas boilers from major UK and European manufacturers
Boiler Brands We Support
We diagnose and repair boilers from many established manufacturers, subject to the model, age of the appliance and availability of suitable parts.
Common brands we attend include Vaillant, Worcester Bosch, Baxi, Ideal, Glow-worm, Viessmann, Keston, Biasi, Alpha, Ariston, Potterton, Ferroli, Intergas and Remeha.
We also have dedicated service and repair information for several major manufacturers:
What Happens During a Boiler Repair Visit?
Tell Us What the Boiler Is Doing
When booking, provide your postcode, boiler make and model if known, the fault code displayed and a short description of the symptoms. Useful information includes whether you have lost heating, hot water or both; whether the pressure is dropping; whether there is a leak; and whether the fault is intermittent or permanent.
We Allocate the Appropriate Engineer
Gas boiler repairs are allocated to a suitably qualified Gas Safe registered heating engineer. Your postcode, appliance type and the information you provide about the fault help us plan the visit appropriately.
The Fault Is Diagnosed
The engineer inspects the boiler and relevant heating controls, carries out appropriate diagnostic checks and identifies the likely reason the appliance is not operating correctly. If an unsafe condition is identified, safety takes priority over keeping the boiler operational.
We Explain the Repair and Cost
Our current Diagnostic Fee & Packages are published on our rates page. The diagnostic visit establishes what is wrong. If further labour or replacement components are needed, the engineer explains the recommended work and associated costs before additional work proceeds. Parts are not replaced simply on the assumption that a fault code identifies the failed component.
Repair, Testing and Reporting
Where the required repair can be completed during the visit, the engineer carries out the work and checks operation afterwards. Where a particular component has to be sourced, we explain the next step and arrange the return repair where appropriate. A written record of the visit can be provided to support property, landlord or maintenance documentation.
Should I Repair or Replace My Boiler?
A boiler breakdown does not automatically mean that the appliance needs replacing.
Repair will often be the sensible option where the fault is identifiable, appropriate replacement parts remain available and the rest of the boiler is in serviceable condition.
Replacement becomes more relevant when the boiler has significant deterioration, important parts are obsolete, repair costs are disproportionate to the condition of the appliance or there is a history of repeated major failures.
There is no single boiler age at which replacement is automatically the right answer. Boiler condition, repair history, parts support, efficiency and the cost of the proposed repair all matter.
Where the choice is not straightforward, we can explain what has failed and whether repairing the existing boiler remains technically and economically reasonable.
Boiler Repair for Homeowners, Landlords and Businesses
Homeowners
Whether you have suddenly lost hot water, your heating will not start or an existing boiler fault is becoming more frequent, we can provide diagnosis and repair without requiring an ongoing service contract.
Landlords and Letting Agents
Boiler failures in rented property often require fast coordination between the tenant, landlord and engineer. We can provide repair reporting and clear information about the fault and work completed. Gas appliances supplied by landlords also need to be maintained safely, with statutory gas-safety requirements remaining separate from an individual breakdown repair.
Property and Facilities Managers
For managed properties, blocks and business premises, we can support individual boiler breakdowns as well as planned heating maintenance. For larger non-domestic boiler plant, see our commercial boiler services rather than this domestic/light-commercial boiler-repair service.
Why Choose Fix & Repair Engineers?
Fix & Repair Engineers is a family-run engineering business supporting heating and catering-equipment customers across London and the Home Counties.
Our approach to boiler repair is based on competent diagnosis and accountable engineering rather than simply changing parts until a fault disappears.
Gas Safe Registered
Gas work is undertaken by engineers appropriately registered for the work involved.
Diagnosis First
We aim to establish the cause of the problem before recommending further repair work.
Transparent Pricing
Our diagnostic pricing is published, and further repairs or parts are discussed before additional chargeable work is undertaken.
Written Reporting
Service and repair records help homeowners, landlords, businesses and facilities teams retain a clear maintenance history.
Fully Insured
Our engineers operate as a professional engineering service rather than an informal handyman call-out.
Boiler Repair Across London and the Home Counties
Fix & Repair Engineers provides boiler-repair services across London and a wide area of the South East. Dedicated local service information is available for:
Boiler Repair in London
Emergency and scheduled boiler fault diagnosis across Greater London.
Boiler Repair in Essex
Boiler breakdown and repair support throughout Essex.
Boiler Repair in Kent
Gas boiler fault diagnosis and emergency repair bookings across Kent.
Boiler Repair in Suffolk
Boiler repair and heating-engineer support across Suffolk.
We also attend properties in Hertfordshire, Berkshire, Oxfordshire, Hampshire, Buckinghamshire, Cambridgeshire, Surrey and Sussex, subject to engineer availability and the type of work required.
If you are searching for a boiler repair engineer near you, send us your postcode and fault details and we can confirm coverage and the earliest suitable appointment.