Vaillant Boiler Repairs

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Vaillant Boiler Repairs London

Gas Safe registered engineers • 24/7 call handling • London wide

Call Now: 0203 868 6251

Tell us the fault code and model. We will advise the safest next step.

Common Vaillant models we repair include ecoTEC Plus, ecoTEC Pro, ecoTEC Exclusive, and ecoFIT Pure, with frequent calls for codes F28, F22, F75, and F29.

We fix Vaillant boiler fault codes, no heating, no hot water, lockout, leaking, and low pressure across London.

We also offer boiler servicing and boiler installation across London.

Quick Navigation

• Safety First
• Quick Checks Before You Call
• Fault Code Table
• Most Searched Problems
• Why Vaillant Boilers Fail
• Models We Repair
• Repair or Replace

Safety First

Smell gas? Turn off the gas supply at the meter if it is safe to do so. Open windows. Leave the property. Call the National Gas Emergency Service on 0800 111 999. Do not use switches, and do not use naked flames.

CO alarm sounding? Open windows immediately. Leave the property. Call 999. Do not re-enter until cleared by emergency services.

Boiler leaking heavily? Turn off the boiler at the controls. If safe, turn off the water supply. Call an engineer.

Quick Checks Before You Call

Before calling an engineer, these safe checks may resolve simple issues with your Vaillant boiler.

Check the gas supply
Is gas working at other appliances in your home? If not, check your meter and any prepayment credit.

Check the pressure gauge
Pressure should read around 1.0 to 1.5 bar when cold. If below 1 bar, you may need to repressurise using the filling loop.

Check the thermostat
Is the room thermostat set above current room temperature? Are the batteries working?

Check the timer or programmer
Is the heating scheduled to be on? Check the clock is set correctly.

Try a single reset
Locate the reset button on your Vaillant boiler. Press once and wait. If the fault returns, do not keep resetting. Call an engineer.

Check the condensate pipe
In cold weather, the external condensate pipe can freeze. Look for a white plastic pipe exiting through an outside wall. If frozen, pour warm water over it gently.

Vaillant Fault Codes

Note: Vaillant fault codes vary by model. If unsure, call us with your model and code and we will advise the safest next step.

Common Vaillant fault codes and what to do

Most Searched Vaillant Problems

If you are seeing a lockout, loss of hot water, or your Vaillant boiler keeps resetting, tell us the fault code and model and we will confirm the safest next step.

F28 – ignition failure

F28 is the most common Vaillant fault code. The boiler tries to ignite but no flame is established. Common causes include gas supply issues, a faulty ignition electrode, or a blocked condensate pipe in winter. Check gas is on elsewhere in the home. Try one reset. If the lockout returns, stop and call an engineer.

F22 – low pressure

If your Vaillant shows F22, system pressure has dropped below the minimum threshold. Top up via the filling loop to around 1.0 to 1.5 bar when cold. If pressure drops again within days, there may be a leak in the system or a failing expansion vessel. Call an engineer to find the cause.

F75 – pump or pressure sensor fault

F75 indicates the boiler cannot detect a pressure change when the pump starts. This can be caused by a faulty pump, a stuck pump, or a failed pressure sensor. Check the pressure gauge first. If pressure is normal, call an engineer to diagnose whether the pump or sensor needs attention.

No hot water but heating works

On Vaillant combi boilers, you may get heating but no hot water, or the reverse. This often points to a diverter valve issue. The diverter valve directs hot water between taps and radiators. When it wears or sticks, hot water delivery becomes unreliable. Call an engineer for diagnosis.

Why Vaillant Boilers Develop Faults

Vaillant is one of the most popular boiler brands in the UK, known for reliability. Here is what we commonly see.

Ignition electrode wear

Ignition faults (F28, F29) can occur when the ignition electrode wears or becomes coated with carbon. Condensate blockages in winter can also contribute to repeated lockouts.

Pump and pressure sensor issues (F75)

The F75 fault is common on Vaillant ecoTEC boilers. It can indicate a seized pump, air in the pump, or a failed pressure sensor. Sometimes the pump just needs freeing off; other times it needs replacing.

Low pressure and expansion vessel faults (F22)

Low pressure faults often point to a failing expansion vessel or a weeping pressure relief valve. The expansion vessel absorbs pressure changes as water heats and cools. If the diaphragm fails or the air charge is lost, pressure drops can occur.

Fan and flue faults (F32, F33)

Fan faults prevent safe combustion and flue gas extraction. The boiler will lock out for safety. Causes include fan motor failure, wiring faults, or flue blockages.

Diverter valve on combi boilers

The diverter valve directs hot water between your taps and radiators. When it wears or sticks, you may get heating but no hot water, or the reverse.

Vaillant Models We Repair

We repair Vaillant combi, system, and regular boilers in London, including:

ecoTEC Plus range: ecoTEC Plus 824, ecoTEC Plus 831, ecoTEC Plus 832, ecoTEC Plus 835, ecoTEC Plus 838
ecoTEC Pro range: ecoTEC Pro 24, ecoTEC Pro 28, ecoTEC Pro 30
ecoTEC Exclusive range: ecoTEC Exclusive with Green iQ
ecoFIT Pure range: ecoFIT Pure 825, ecoFIT Pure 830, ecoFIT Pure 835
Other models: Turbomax, ecoMAX, and older Vaillant units

Vaillant parts are widely available through their UK network. We check availability before attending and advise honestly if repair is not viable or cost effective.

Repair or Replace Your Vaillant Boiler?

We help you decide based on age, reliability, and parts availability.

Repair makes sense when

• Boiler is under 10 years old
• This is the first major fault
• Parts are readily available
• Boiler has been regularly serviced

Replacement may be better when

• Boiler is 12 to 15 years old or more
• You have had multiple breakdowns recently
• Parts are obsolete or hard to source
• The boiler is undersized for the property
• Energy bills are higher than expected for the property size

Our engineers give honest assessments. We focus on safety and reliability, not pushing unnecessary replacements.

Vaillant Boiler Servicing

Annual servicing reduces breakdown risk and keeps your Vaillant boiler running efficiently. See Boiler servicing London.

Landlords and Letting Agents

We provide boiler repairs and gas safety certification for landlords across London. See Landlord gas safety certificate (CP12).

Vaillant Repairs Across London

London wide coverage for Vaillant boiler repairs. Book an engineer or view our London areas we cover.

Have your postcode and fault code ready and we will confirm the quickest appointment slot.

Other Boiler Brands We Repair

Worcester • Ideal • Baxi • Glow-worm • Viessmann • Potterton • Main • Vokera • Alpha • Ferroli

View all brands

Vaillant Boiler Repair FAQs

How quickly can you attend for a Vaillant breakdown?

We offer same day attendance where slots are available. For no heating or hot water, we prioritise urgent breakdowns. Call our 24/7 line and we will advise availability.

Do you carry Vaillant parts?

We stock common Vaillant parts including diverter valves, pumps, pressure sensors, ignition electrodes, fans, and PCBs. Vaillant parts are widely available.

Is it safe to reset my Vaillant boiler?

Try one reset. If the fault returns after resetting, stop and call an engineer. Do not reset at all for F27 faults.

How much does a Vaillant boiler repair cost?

Costs vary depending on the fault and parts required. We diagnose first and quote before any repair work begins.

Related Services

• Emergency boiler repairs
• Boiler servicing London
• Boiler installation London
• Power flush London
• Landlord gas safety certificate (CP12)
• London areas we cover

Speak to Our Team

For safe next steps, call now.

Call 0203 868 6251 | Book an Engineer

Gas Safe registered • 24/7 call handling • Quote before work