Dimplex Boiler Repairs London

Dimplex Boiler Repair Help Centre

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

Jump to:
Identify Your Display ·
Fault Codes ·
Code 3 Ignition ·
Water/Pressure ·
Frozen Condensate ·
Repair or Replace

Quick Checks Before You Call Anyone

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

1. Note the exact display: Is it showing a single character/number (for example 3, P, A) or a longer code? Write it down exactly and take a photo.
2. Check your fuse box: Boilers need electricity; a tripped switch is an easy fix.
3. Check thermostat and timer/programmer: Settings can change after clock changes or dead batteries.
4. Check gas supply (if safe): Do other gas appliances work (hob/cooker)? If not, it may be a supply issue.
5. Freezing weather? If your boiler is a condensing model, the condensate pipe may be frozen (see winter section below).
6. Reset once only: Use the boiler’s reset (or follow the reset instructions on the control). If it locks out again, stop and call an engineer.

Dimplex Gas Boilers in London: What To Expect

Dimplex is best known for electric heating products, but older UK installations do include Dimplex-branded gas boilers. In London we typically see these in 2000s-era installs, and many are now approaching end of life. The key to fast diagnosis is reading the display correctly and avoiding assumptions about system type (open-vented vs sealed).

Identify Your Display (Very Important)

Before using the fault-code table, check how your boiler shows faults:

• Single character / number on a 7-segment display (for example 1, 3, 0, P, A): common on older Dimplex gas boilers.
• Longer codes or text: different model/platform. Tell us the exact code and we’ll match the right system.

Tip: You can usually find the model name on the front fascia, an underside data label, your Benchmark/installation paperwork, or a service label near the boiler. Please do not remove the boiler casing.

Dimplex Boiler Fault Codes

Use the table that matches what you see. If you’re unsure, send us the model name and a photo of the display.

Code 3: Ignition Lockout / No Flame

What is happening: The boiler has tried to ignite several times but cannot establish a stable flame.

Common causes: Gas supply interruption, ignition/flame sensing components, flue/air issues, or (on condensing models) a frozen condensate pipe in winter.

What to try: Check if your gas hob/cooker works. If freezing outside and your boiler is a condensing model, check the condensate pipe section below. Reset once only. If it returns, call an engineer.

Water, “Pressure”, and System Type (Don’t Guess)

Dimplex gas boilers are found on different system types. Before following any “pressure top up” guidance, confirm what you have:

• Sealed system (often combi/system boilers): usually has a pressure gauge and a filling loop. Normal cold pressure is typically 1.0–1.5 bar.
• Open-vented system (common on older installs): typically does not have a filling loop for topping up pressure in the same way. If you’re unsure, we’ll identify it from photos/model details.

How to Top Up Pressure (Only If You Have a Gauge + Filling Loop)

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

Do not remove the boiler casing to locate a filling loop.

1. Locate the filling loop (often underneath the boiler or near the pipework).
2. Ensure the boiler is off and cool.
3. Open the valve(s) slowly.
4. Watch the gauge rise to between 1.0 and 1.5 bar.
5. Close the valve(s) fully.
6. Switch the boiler back on and reset if required.

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

If you need to top up frequently (more than once a month), there is likely a leak. Call us for a diagnosis. More detail in our complete pressure guide.

Frozen Condensate Pipe (Winter)

If your Dimplex is a condensing boiler and the weather is freezing, a frozen condensate pipe can cause ignition-related lockouts. This is often safe to resolve yourself. If you are unsure, call an engineer.

Signs: Boiler locked out, freezing temperatures outside, gurgling sound when boiler tries to start, and the condensate pipe runs outside.

What to do:

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

Do not use a naked flame or heat gun on plastic pipework.

Full instructions: Frozen condensate pipe guide.

If it keeps happening, we can reroute the pipe internally or add insulation to reduce repeat freezing.

Why These Faults Occur in London Homes

London’s housing stock and water conditions push certain failure patterns:

• Overheat / circulation faults (1 / 0 / 2): Sludge (magnetite) and limescale can restrict flow, especially in older systems and hard-water areas.
• Ignition lockouts (3): Winter condensate freezing (where externally routed) and general age-related wear on ignition/flame sensing components.
• Fan/flue safety faults (7 / 4): Older flue components and airflow proving faults should be treated as engineer-only.

Dimplex Boiler Models We Repair

We repair older Dimplex-branded gas boilers found across London, including model families commonly seen in UK installations such as:

• Dimplex 18 OV / 32 OV: Open-vented condensing boiler range (older installs)
• Dimplex Combi: Dimplex-branded combination boilers (varies by year/platform)
• Dimplex System: System boiler variants used with cylinders

Note: If you have a Dimplex electric boiler, storage heater, electric cylinder, or heat pump, that is a different appliance type and usually requires different specialists. This page focuses on gas boilers.

Dimplex: Parts and Support

Because Dimplex gas boilers are far less common than mainstream brands today, parts can be more variable to source, especially for older models. We’ll give you a clear, practical view on repair viability once we know the model and code.

Common Dimplex Gas Boiler Problems

Ignition lockouts (3): Often linked to gas supply interruptions, ignition/flame sensing wear, or winter condensate freezing on condensing installs.

Circulation/overheat issues (0/1/2): Common on older systems with sludge, restricted flow, or pump issues.

Fan/flue proving faults (7/4): Safety-related faults requiring engineer diagnosis.

Control/PCB faults (A/C/E/h): Intermittent lockouts, display issues, or internal errors on older electronics.

Repair or Replace?

If your Dimplex needs a major repair (heat exchanger, PCB, gas valve) and is older, it’s worth weighing up replacement with a more widely supported modern boiler.

Signs it may be time to replace:

• Multiple faults in the past 12 months
• Parts becoming difficult or expensive to source
• Boiler is older and efficiency has noticeably declined
• Repeated safety lockouts (fan/flue/overheat related)

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.

Dimplex Boiler Servicing

Annual servicing helps keep older boilers running safely and efficiently, and can catch developing faults before they become expensive failures.

We service gas boiler brands across London. 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: Older/less common boilers can become a recurring cost. Stay compliant with our Gas Safety Certificate (CP12) service. See our full London landlord checklist.

London Wide Coverage

We repair boilers across all London boroughs including North, South, East, West, and Central London.

For coverage and service areas, see our London coverage page.

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What We Need From You (To Diagnose Faster)

• Boiler model: the exact name shown on the fascia, underside label, or paperwork (no casing removal)
• Display code: the exact character/number shown (for example 3 / 0 / P / A)
• System type: do you have a pressure gauge + filling loop (sealed), or not sure (we’ll help you identify)
• Postcode: so we can route the closest engineer
• Gas supply check: whether other gas appliances work (hob/cooker)

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