Keston Boiler Repairs London

Keston Boiler Repair Help Centre

Common Keston faults, fault codes, safe checks, and when to call a Gas Safe engineer.

We specialise in Keston boiler repairs across London.

Gas Safe registered engineers for safe diagnosis, repair and testing.

24/7 availability with London wide call handling and booking.

Jump to: Fault Codes · E01 Ignition · Pressure · Frozen Condensate · Repair or Replace

Quick Checks Before You Call Anyone

These take 60 seconds and solve a surprising number of lockouts:

1. Check the pressure gauge: If below 1 bar, top up to 1.0 to 1.5 bar. More detail in our complete pressure guide.
2. Note the fault code: Keston displays may show codes like E01, E03, E05 or L2 depending on model. Write it down before calling.
3. Check your fuse box: Boilers need electricity, a tripped switch is an easy fix.
4. Check thermostat and timer: Settings can change after power cuts or dead batteries.
5. Freezing weather? The condensate pipe may be frozen (see winter section below).
6. Reset once only: Use the reset button on the front panel once, then wait 60 seconds. If it locks out again, stop and call an engineer.

Keston Fault Codes

Note: Keston fault codes vary by model and generation. If your code is not listed here, call us with the exact code and model and we will advise the safest next step.

E01: Ignition Failure

What is happening: The boiler is trying to light but cannot establish a stable flame after multiple attempts.

Common causes: Gas supply interruption, frozen condensate pipe (winter), ignition components, flue or airflow issues, gas valve or PCB related faults.

What to try: Check your gas hob or other gas appliances work. In freezing weather, check the condensate pipe for ice. Reset once only. If the boiler will not ignite, call an engineer.

Low Pressure Symptoms

What is happening: If the pressure drops below the minimum operating level, the boiler may lock out to protect itself.

What to try: Top up to 1.0 to 1.5 bar using the filling loop. If you need to top up frequently, there is likely a leak or a component issue. Use our pressure guide for step by step help.

How to Top Up Pressure (Keston)

If you are not comfortable using the filling loop, stop and call a Gas Safe engineer.

Do not remove the boiler casing. If you cannot locate the filling loop easily, call an engineer.

1. Locate the filling loop (often underneath the boiler, a braided silver hose with one or two valves).
2. Ensure the boiler is off and cool.
3. Open the valves slowly, a quarter turn at a time.
4. Watch the pressure rise to between 1.0 and 1.5 bar.
5. Close both valves fully.
6. Switch the boiler back on.

Do not exceed 2.0 bar. If you overfill, stop and call an engineer.

Frozen Condensate Pipe (Winter)

In freezing weather, a frozen condensate pipe can cause ignition related lockouts on condensing boilers. This is often safe to resolve with the steps below. If you are unsure, or the boiler will not restart, call an engineer.

Signs: Lockout during freezing temperatures, gurgling when the boiler tries to start, repeated ignition failures.

What to do:

1. Locate the condensate pipe (white or grey plastic pipe running to an outside drain).
2. Pour warm water (not boiling) over the frozen section.
3. Reset the boiler once thawed.

Full instructions: Frozen condensate pipe guide.

Why These Faults Are Common in London Homes

Hard water, older pipework, and winter weather make certain faults more likely in London properties:

• Ignition lockouts: Winter condensate freezing and inconsistent gas supply symptoms can trigger repeated lockouts.
• Circulation and overheating: Sludge and limescale can restrict flow, raising temperatures and triggering safety shut downs.
• Pressure drops: Older systems can lose pressure after radiator bleeding or due to small leaks.

Keston Models We Repair

We repair Keston boiler models including:

• Combi models: Combi 2 and other domestic combi ranges
• System and heat only: Domestic system models and older installations
• Older ranges: C series boilers and legacy Keston models still common in London properties

Keston boilers are often chosen for challenging flue routes. We work on both domestic and light commercial style installations across London.

Common Keston Problems

Ignition lockouts: Repeated failed ignition attempts, often linked to gas supply, condensate freezing, ignition components, or airflow issues.

Fan and airflow faults: Fan proving errors or airflow related safety shut downs.

Overheating or poor circulation: Restricted flow caused by sludge, limescale, stuck valves, or pump issues.

PCB and sensor faults: Intermittent lockouts or inconsistent readings that need safe testing.

Kettling and noise: Scale and debris can cause overheating and noises. See our guide to boiler noises.

Repair or Replace?

Keston boilers typically last 10 to 15 years with proper maintenance. If yours is approaching that age and needs a major repair (PCB, fan assembly, heat exchanger), replacement may be more cost effective.

We give honest advice either way. Read more: Repair or replace? An engineer’s guide.

If you decide on a new boiler: New boiler installation.

Keston Servicing

Annual servicing helps keep your Keston running safely and efficiently. We service Keston models and provide a clear report after each visit.

We recommend servicing in late summer or early autumn, before the heating season. Book your boiler service.

Renting? Landlords: Check This

Tenants: Your landlord is usually responsible for boiler repairs. Contact them first and keep written records, especially if you have no heating or hot water.

Landlords: Stay compliant with our Gas Safety Certificate (CP12) service. See our full London landlord checklist covering gas safety, EPCs, and boiler maintenance.

London Wide Coverage

We repair Keston boilers across all London boroughs. See our London coverage area or find your local page:

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