What should I do if I see F.28 or F.29 on a Vaillant boiler?

Both are ignition faults. F.28 means the boiler failed to ignite; F.29 means the flame was lost during operation. In winter, a frozen condensate pipe is the most common cause — pour warm, not boiling, water over the pipe, then press Reset for 3–5 seconds. If that doesn't resolve it, a Gas Safe engineer needs to check the gas valve and spark electrode.

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Vaillant Advance Partner across Wokingham · Arborfield · Earley · Shinfield · Woodley · Finchampstead · Winnersh · RG40 · RG41

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Vaillant Advance Partner · Gas Safe 599015 · RG40

Vaillant boiler support · Wokingham & RG40

Vaillant Boiler Support & Fault Codes — Wokingham

ecoTEC Plus, ecoTEC Pro, ecoTEC Exclusive & ecoFIT Pure — fault codes, servicing & repairs from Wokingham’s Vaillant Advance Partner

Whether your Vaillant boiler is showing an F.22, F.75 or F.28 fault code, needs its annual warranty service, or has broken down entirely — Thermotec is Wokingham’s Vaillant Advance Partner. The highest tier of Vaillant accreditation. Fixed prices, exact arrival times, 90% first-time fix rate. Calls answered 24/7.

Book Online 24/7 Call 07850 116944

Advance

Vaillant
Partner

£96

Service &
diagnostic

90%

First-time
fix rate

130+

5★ Google
reviews

Need Vaillant help today?

Repairs · Servicing · Fault codes · RG40

Calls answered 24/7 · Stuart follows up first thing

Annual serviceFrom £96

Diagnostic fee£96 fixed

First-time fix90%

Google reviews130+ ★

Book Online 24/7 07850 116944

★★★★★

130+ five-star Google reviews from homeowners across Wokingham, Earley, Shinfield and RG40

Vaillant Advance Partner Gas Safe 599015 £96 fixed diagnostic 90% first-time fix Calls answered 24/7

★

Vaillant Advance Partner

The highest tier of Vaillant accreditation — factory-trained on the full ecoTEC range

What do you need?

Fault codes or annual servicing?

Fault code guide

Vaillant Fault Codes

F.22, F.28, F.29, F.75 and more — full ecoTEC fault code index with severity ratings, DIY fixes and step-by-step guidance for all models.

F.22, F.75, F.28 — full index → Reset guide for all ecoTEC models → When to call an engineer →

Diagnostic from £96

Annual servicing

Vaillant Boiler Service

Annual service by a Vaillant Advance Partner — the highest accreditation tier. Digital Benchmark record same day. Warranty-compliant. From £96 fixed price.

What’s included in the service → Advance Partner accreditation explained → Book your exact time online →

From £96 · Fixed price

Quick fault lookup

Most common Vaillant fault codes

These are the codes Wokingham homeowners report most often on ecoTEC Plus, Pro and Exclusive models. See the full fault code guide for the complete index.

F.22

Low water pressure

Repressurise to 1.5 bar using the filling loop. If pressure keeps dropping, hidden leak or failing expansion vessel — engineer required.

F.75

Pump / pressure sensor fault

Pump not detected on startup or pressure sensor blocked with magnetite sludge. Common in Wokingham’s hard water area. Engineer needed.

F.28

Ignition failure

Gas supply issue, frozen condensate pipe in winter, or faulty spark electrode. Check gas supply and condensate pipe before calling.

F.29

Flame loss lockout

Flame established then lost. Gas valve or ionisation sensor fault. Press Reset once — if it returns immediately, engineer required.

F.27

Flame without demand

Gas valve fault. Turn off at wall immediately. Do not restart. Safety-critical — Gas Safe engineer required before use.

F.32

Fan fault

Fan not operating correctly — prevents safe venting. Do not reset repeatedly. Gas Safe engineer required immediately.

View full fault code guide →

Models we support

Vaillant ecoTEC range — all models covered

As a Vaillant Advance Partner, Thermotec is trained and equipped to service, repair and diagnose all current ecoTEC and ecoFIT models across Wokingham and RG40.

ecoTEC Plus

Most common in RG40

The UK’s most popular Vaillant combi. Award-winning reliability, ErP A-rated, weather compensation capable. F.22 and F.75 are the most common codes.

Fault code guide → Download manual (PDF) →

ecoTEC Pro

Mid-range combi

Compact and efficient combi. F.28 ignition and F.22 pressure faults are the most reported. Identical reset procedure to the ecoTEC Plus.

Fault code guide → Download manual (PDF) →

ecoTEC Exclusive

Premium combi & system

Vaillant’s premium flagship. Integrated VR900 controls, weather compensation and Vaillant Sense compatible. Advanced diagnostics via engineer mode.

Fault code guide → Download manual (PDF) →

ecoFIT Pure

System boiler

System boiler for properties with hot water cylinders. Clean installation design. F.22 and circulation faults are the most common on this model.

Fault code guide → Download manual (PDF) →

ecoTEC Plus / Pro Combi

Combi variant

Combined Plus/Pro combi variant. Same fault code structure as the standard ecoTEC range. F.75 pump fault common where system sludge is present.

Fault code guide → Download manual (PDF) →

PDF manuals

Download Vaillant manuals

User, installation and servicing manuals for all major Vaillant ecoTEC models. Click to download direct.

PDF

ecoTEC Plus

Installation & user manual

PDF

ecoTEC Pro

Installation & user manual

ecoTEC Plus / Pro Combi

Installation & user manual

Why choose Thermotec

Wokingham’s Vaillant Advance Partner

Advance Partner is Vaillant’s highest tier of accreditation. It means Stuart has completed Vaillant’s own training programme and is recognised by the manufacturer as a trusted specialist for the full ecoTEC range.

Vaillant Advance Partner

The highest tier of Vaillant accreditation. Factory-trained on the full ecoTEC and ecoFIT range. Services and repairs recognised by Vaillant to protect your manufacturer warranty.

Advanced diagnostics

Expert troubleshooting for all F codes — F.22, F.28, F.75, F.32. We use Vaillant’s own diagnostic protocols, not trial and error parts-swapping.

Genuine parts

Only manufacturer-approved Vaillant parts used. Common items — pressure sensors, electrodes, diverter valves — carried on the van for same-visit fixes.

Exact arrival times

Book online 24/7 and Stuart arrives when he says he will — not a 6-hour window. 130+ five-star Google reviews from Wokingham homeowners confirm it.

Transparent pricing

£96 fixed diagnostic, annual service from £96. Price confirmed before work begins — no hidden hourly rates or national-company markups.

Local & family-run

Based in Arborfield, 10 minutes from Wokingham town centre. You speak directly to Stuart — the engineer who arrives, not a call centre. Gas Safe Reg. 599015.

Common questions

Vaillant boiler FAQ

What does the F.22 fault code mean on my Vaillant?

F.22 indicates low water pressure. This is one of the most common Vaillant faults — often caused by a leak, or by recently bleeding radiators. You can usually resolve it by topping up the system pressure to 1.5 bar using the filling loop (usually a small lever handle under the boiler). If the pressure drops repeatedly, you likely have a failing expansion vessel or a hidden leak — book a diagnostic to find the cause.

Why is my Vaillant showing F.75?

F.75 means the boiler is trying to start the pump but isn’t detecting a pressure rise — either the pump has seized or the pressure sensor is blocked with magnetite sludge. It’s very common in Wokingham’s hard water area. Resetting may work temporarily but the underlying cause needs addressing. We carry genuine Vaillant pressure sensors on the van. A powerflush and a magnetic filter prevent recurrence.

What should I do if I see F.28 or F.29?

Both are ignition faults. F.28 means the boiler failed to ignite; F.29 means the flame was lost during operation. In winter, a frozen condensate pipe is the most common cause — locate the white plastic pipe exiting the wall, pour warm (not boiling) water over it, then press Reset for 3–5 seconds. If the fault isn’t caused by the condensate pipe, a Gas Safe engineer needs to check the gas valve and spark electrode.

How do I reset my Vaillant ecoTEC boiler?

Look for the button with a flame symbol with a cross through it, or a button labelled ‘Reset.’ Press and hold for 3–5 seconds. If the fault code returns immediately after a reset, stop — do not keep pressing. This indicates a persistent safety issue requiring a professional diagnostic. See the full fault code guide for model-specific reset instructions.

My Vaillant boiler is kettling — is this dangerous?

Not immediately dangerous, but it’s a serious warning sign. Kettling is caused by limescale or sludge on the heat exchanger restricting water flow, making water boil locally. Left untreated it causes the heat exchanger to crack — an expensive repair. A professional powerflush clears the debris. Adding a magnetic filter prevents it recurring. Common in Wokingham’s hard water area.

How often should I service my Vaillant boiler?

Annually. Vaillant warranties require an annual Gas Safe service to remain valid. As a Vaillant Advance Partner, Thermotec issues the digital Benchmark record Vaillant requires as proof. See the Vaillant boiler service page and the annual boiler servicing page for full detail.

Coverage