Vaillant is one of the UK’s most-installed boiler brands, and the ecoTEC range generates some of the highest fault code search volumes of any boiler in the market. The F75 fault code alone attracts over 1,300 searches per month in the UK — homeowners and engineers alike searching for the component behind Vaillant’s most common failure mode.
We stock genuine Vaillant ecoTEC spare parts for the Pro, Plus, and Exclusive ranges — pumps, pressure switches, gas valves, PCBs, fan motors, heat exchangers, and diaphragm kits. Next day delivery on all in-stock lines when ordered before 3pm.
Key Boiler Ranges
ecoTEC Pro
The ecoTEC Pro is Vaillant’s mid-range combi boiler, available in 24kW, 28kW, and 35kW outputs. Widely installed in UK new-builds and replacements from 2009 onwards.
ecoTEC Plus
Premium version with higher output options (up to 48kW) and enhanced modulation range. Parts compatibility with Pro models varies by component — always confirm ecoTEC variant before ordering PCBs, pumps, or gas valves.
ecoTEC Exclusive
Vaillant’s top-tier combi with built-in smart thermostat compatibility and OpenTherm connectivity. PCB and control architecture differs significantly from older ecoTEC models.
Most-Searched Vaillant Parts
Pump Assembly: Directly related to the F75 fault. We stock both the complete pump assembly (Grundfos-based, ecoTEC specific) and the pressure switch separately.
Pressure Switch (Differential Pressure Switch): The most searched Vaillant spare part in the UK. It measures the pressure differential across the pump — if the pump runs but the pressure switch doesn’t confirm it, F75 locks out the boiler.
Gas Valve: Vaillant gas valve failure typically presents as F27 (flame failure) or F28 (ignition failure). Must be replaced by a Gas Safe engineer.
PCB (Control Board): PCB failure on Vaillant ecoTEC produces a range of fault codes and behaviours. OEM PCBs are strongly recommended.
Ignition Lead and Electrode: Vaillant F28 indicates ignition failure — the most common cause is a degraded ignition lead or cracked electrode.
Fan Motor: Vaillant fan faults appear as various fault codes depending on model.
Vaillant Fault Codes
F75 — Pump/Pressure Switch Fault
The most common Vaillant fault. Over 1,300 searches per month in the UK.
F75 triggers when the differential pressure switch does not detect the expected pressure change when the pump starts. Causes:
- Blocked pump — pump motor runs but impeller is blocked by sludge/scale
- Failed pump — motor not running
- Failed pressure switch — pump is running correctly but switch not registering
- Air trapped in pump — common after system draindown
Parts linked to F75: Pump assembly, differential pressure switch, pump capacitor.
F22 — Low System Pressure
Not strictly a component fault — F22 indicates the system pressure has dropped below the operating threshold. If F22 recurs after topping up: Inspect the expansion vessel. If water comes out when you test it with a tyre pump, the bladder has failed.
Parts linked to F22: Expansion vessel, pressure gauge.
F28 — Ignition Failure
Parts linked to F28: Ignition electrode, ignition lead, gas valve, PCB.
F27 — Flame Loss During Operation
The flame has been established but then lost during normal operation. Distinct from F28 (failure to ignite at all).
Parts linked to F27: Gas valve, flame rectification electrode, flue gas thermostat.
Compatible Vaillant Models
ecoTEC Pro 24, 28, 35; ecoTEC Plus 24, 28, 35, 48; ecoTEC Exclusive 35, 38; VC 346 and VC 436 system variants; ecoMAX 613/618/635 (legacy); turboMAX Pro/Plus (legacy).
Need a Vaillant Engineer Near You?
Fault diagnosis on a Vaillant — particularly distinguishing between F75 pump failure and F75 pressure switch failure — requires hands-on testing.
Our Recommended Installers have experience with the full Vaillant ecoTEC range:
- HGB Heating Kent — Gas Safe engineers, Vaillant specialists, Kent and Medway
- Boiler Sense — Certified boiler specialists, ecoTEC fault diagnosis and repair, Kent and South East London