Pro Boiler Repairs London

Pro Boiler Repair London

Gas Safe engineers in London with honest advice on Pro boilers – including when replacement is the smarter investment.

Jump to:
Quick Checks ·
Common Faults ·
Parts Reality ·
Replacement Option ·
Repair vs Replace ·
Landlords

Quick Checks (60 Seconds)

Before calling anyone, these basic checks resolve many apparent boiler failures:

1. Check your fuse box: a tripped breaker mimics a dead boiler.
2. Check thermostat and timer: power cuts reset schedules; wireless stats need fresh batteries.
3. Check the pilot light (if fitted): older Pro boilers may have a standing pilot. If out, relight once using panel instructions. If it won’t stay lit, stop and call us.
4. Check system pressure (sealed systems only): if your gauge shows below 1 bar, see our pressure guide before topping up.
5. Reset once only: if the boiler locks out again after one reset, do not keep trying. Call a Gas Safe engineer.

Common Pro Boiler Problems

Pro boilers still in service are typically 20-30+ years old. At that age, certain failures become inevitable:

• Ignition failure: worn electrodes, degraded ignition leads, or a failing gas valve prevent the boiler lighting. On older units with a pilot, thermocouple wear is common.
• Pilot light problems: pilot won’t stay lit, often due to thermocouple failure, blocked pilot jet, or intermittent gas valve.
• No heating or hot water: could be a seized pump, failed motorised valve, or (on combis) a stuck diverter.
• Low pressure / pressure loss: indicates a leak in the pipework, a faulty expansion vessel, or a weeping pressure relief valve.
• Leaking from boiler: internal seals, heat exchanger corrosion, or pump gland failure. Water and gas appliances don’t mix – call an engineer promptly.
• Strange noises: banging, kettling, or gurgling point to sludge buildup, limescale, trapped air, or pump wear. More detail in our guide to boiler noises.
• PCB or control faults: random lockouts, display failures, or erratic behaviour. On obsolete boilers, replacement PCBs are often unavailable.
• Overheat lockouts: usually circulation-related – blocked pump, sludged system, or failed overheat stat.

Fault codes vary by Pro model. If your display shows a code, note it exactly (or photograph it) and tell us when you call.

What We Check on Arrival

If we visit a Pro boiler, our Gas Safe engineer will typically:

• Confirm the exact model and check the data plate for any manufacturer cross-references
• Inspect for visible leaks, corrosion, scorch marks, or flue issues
• Test gas pressure and burner operation (where safe to do so)
• Check system pressure, pump operation, and controls
• Assess parts availability realistically before quoting

The Parts Reality for Pro Boilers

Pro boilers have been out of production for many years. That creates a practical problem: when something fails, sourcing the right part can be difficult, slow, or impossible.

• Generic parts (pumps, valves, thermostats) may still be available if they’re shared with other brands.
• Brand-specific parts (PCBs, gas valves, heat exchangers) are often discontinued and unavailable.
• Even when parts exist, the cost and delay can exceed the value of the repair on a boiler this old.

We won’t waste your money chasing parts that don’t exist. If repair isn’t viable, we’ll tell you straight.

Why These Problems Are Common in London

London’s housing stock and water supply contribute to boiler wear:

• Hard water: limescale builds up in heat exchangers, reducing efficiency and causing overheating.
• Older pipework: Victorian and Edwardian properties often have corroded pipes that shed debris into the system.
• External condensate routing: on any condensing boiler, externally routed condensate pipes freeze in cold snaps (see our frozen condensate guide).
• System sludge: years of circulation without a power flush leaves black oxide sludge that blocks pumps and heat exchangers.

Repair vs Replace: A Straightforward Comparison

When an obsolete boiler fails, the repair vs replace maths usually points one way.

Example repair scenario (illustration only): Diagnosis plus a component repair on an older Pro boiler might cost around £350-£450 depending on fault, parts availability, and access.

• Afterwards, you still have a 20-30 year old boiler with no warranty.
• If another part fails in 6-12 months (common at end-of-life), you pay again.
• Efficiency stays the same – you can’t repair an old boiler into a modern efficient one.

Compare that to a new installation from £1,899:

• Warranty-backed for years, not months.
• Parts readily available for future servicing.
• Typically more efficient than older units (exact savings vary).
• One planned cost vs repeated emergency repairs.

We give the same advice we’d give family: if the boiler is at end-of-life, replacing it is usually the better investment. More detail in our repair vs replace guide.

Landlords: Plan Ahead

If you’re a landlord with a Pro boiler in a rental property, proactive replacement makes business sense:

• Tenant retention: heating breakdowns drive complaints, bad reviews, and void periods.
• Predictable costs: a planned installation costs less disruption than emergency call-outs.
• Compliance simplicity: modern boilers pass annual Gas Safety Certificates more reliably.
• EPC improvement: an efficient boiler can lift your Energy Performance Certificate rating (property-specific).

See our London landlord checklist for more guidance.

Still Want a Repair Assessment?

Understood. We can diagnose the fault and confirm whether parts exist before you commit to anything. Our diagnostic visit fee is deducted from any work you proceed with.

Just be prepared for the honest answer – sometimes the kindest thing we can say is “this isn’t worth fixing”.

Brands We Install

When it’s time to upgrade, we’ll recommend a boiler that fits your property, budget, and hot water demand:

London Wide Coverage

We install and service boilers across all London boroughs. See our London coverage page for service areas.

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