Baxi
The Baxi Duo-tec 24 Combi ErP is a 24 kW natural gas condensing combi boiler with a 92% seasonal efficiency and a domestic hot water flow rate of 11.43 litres per minute at a 30°C rise.
The Baxi Duo-tec 24 Combi ErP is a natural gas condensing combi boiler designed for wall-hung installation in UK domestic properties. This model, identified by GC number 47 075 96, provides both central heating and domestic hot water. It is part of the wider Duo-tec Combi family, which includes variants up to 40 kW. This page details specific technical specifications, fault codes, and installation requirements for heating engineers and homeowners.
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Full technical specifications extracted from the manufacturer brochure. Empty sections are hidden.
Heating Flow (22mm), Domestic Hot Water Outlet (15mm), Gas Inlet (22mm), Cold Water Inlet (15mm), Heating Return (22mm), Pressure Relief Valve (15mm)
All systems must be thoroughly flushed and treated with inhibitor (see section 6.2). System additives - corrosion inhibitors and flushing agents/descalers should comply to BS7593 requirements.
For full terms and conditions, visit www.baxi.co.uk/terms. Failure to adhere to terms and conditions will void your manufacturer's warranty.
The Baxi Duo-tec 24 Combi ErP is a natural gas condensing combi boiler, providing a maximum central heating output of 21 kW and a domestic hot water output of 24 kW. It achieves a seasonal efficiency of 92% and is rated NOx Class 5, with emissions of 20 mg/kWh. The boiler delivers a domestic hot water flow rate of 11.43 litres per minute at a 30°C temperature rise, suitable for standard domestic requirements. Physical dimensions are 780mm high, 450mm wide, and 345mm deep, with a dry weight of 40.2 kg. Installation requires specific clearances and adherence to water quality standards, including thorough flushing and inhibitor treatment. Electrical consumption is 85W maximum, with a standby power of 3W. Flue options include horizontal and concentric types, with diameters of 60/100mm and 80/125mm, supporting maximum horizontal lengths of 10 metres.
Every fault code listed in the manufacturer brochure, with likely causes and engineer actions. Each code has a permalink — paste a URL like https://www.boilertag.com/boilers/baxi/baxi-duo-tec-40-combi-erp#fault-e20 to jump straight to the entry.
| Code | Meaning | Details |
|---|---|---|
| E20 | Central Heating NTC Fault Show causes & actionsE20, E28 & E50 indicate faulty components. Likely causes
Engineer action Go to section 'E' (Temperature sensors faulty. Replace sensor). | Details |
| E28 | Flue NTC Fault Show causes & actionsE20, E28 & E50 indicate faulty components. Likely causes
Engineer action Go to section 'E' (Temperature sensors faulty. Replace sensor). | Details |
| E50 | Hot Water NTC Fault Show causes & actionsE20, E28 & E50 indicate faulty components. Likely causes
Engineer action Go to section 'E' (Temperature sensors faulty. Replace sensor). | Details |
| E110Lockout | Safety Thermostat Operated Show causes & actionsshows overheat of the primary water Likely causes
User action Turn the selector switch to reset position for 5 seconds Engineer action Allow to cool. Continuity across thermostat terminals more than 1.5 ohm. Replace safety thermostat. Reset procedure Turn the selector switch to the 'Reset' position for a minimum of 5 seconds | Details |
| E119 | Water Pressure Switch Not Operated Show causes & actionsdisplayed when the primary water pressure is less than 0.5 bar. Likely causes
Engineer action Re-pressurise system. Check connection water pressure switch terminal COM - NO and PCB connector X400 terminals 3,4. Replace water pressure switch. | Details |
| E125 | Circulation Fault (Primary Circuit) Show causes & actionsi) If within 15 seconds of the burner lighting the boiler temperature has not changed by I°. ii) If within 10 minutes of the burner lighting the boiler temperature twice exceeds the selected temperature by 30°. In these instances poor primary circulation is indicated. Likely causes
Engineer action Ensure that primary circulation is OK & that there is no blockage. | Details |
| E130Lockout | Flue NTC Operated Show causes & actionsoverheat of the flue system. Likely causes
User action Turn the selector switch to reset position for 5 seconds Engineer action Check the Central Heating NTC sensor. Go to section 'E' (Temperature sensors faulty. Replace sensor). Reset procedure Turn the selector switch to the 'Reset' position for a minimum of 5 seconds | Details |
| E133Lockout | Interruption Of Gas Supply or Flame Failure Show causes & actionsindicates that the gas supply has been interrupted, ignition has failed or the flame has not been detected. Likely causes
User action Turn the selector switch to reset position for 5 seconds Engineer action Check supply pressure at the gas valve. Check and correct if necessary: The mechanical set of the gas valve (CO2 values - see instruction), Flame sensing electrode and lead connections, Flame sensing electrode position. Flame current should be more than 0.5 μA. Replace flame sensing electrode. Reset procedure Turn the selector switch to the 'Reset' position for a minimum of 5 seconds | Details |
| E160 | Fan or Fan Wiring Fault Show causes & actionsLikely causes
Engineer action Fan connections correct at fan. PCB - X2 connector, is 230V AC across terminals 3 & 4. Fan jammed or faulty winding. Replace fan. Replace PCB. | Details |
| E193 | Pre-Circulation Fault Show causes & actionsLikely causes
Engineer action Ensure that primary circulation is OK & that there is no blockage. | Details |
Patterns that group across the manufacturer's fault-code table. Each entry links to the full code listing further down the page.
User: Turn the selector switch to reset position for 5 seconds
Engineer: Allow to cool. Continuity across thermostat terminals more than 1.5 ohm. Replace safety thermostat.
Triggered by fault code E110.
User: Turn the selector switch to reset position for 5 seconds
Engineer: Check the Central Heating NTC sensor. Go to section 'E' (Temperature sensors faulty. Replace sensor).
Triggered by fault code E130.
User: Turn the selector switch to reset position for 5 seconds
Engineer: Check supply pressure at the gas valve. Check and correct if necessary: The mechanical set of the gas valve (CO2 values - see instruction), Flame sensing electrode and lead connections, Flame sensing electrode position. Flame current should be more than 0.5 μA. Replace flame sensing electrode.
Triggered by fault code E133.
Engineer: Go to section 'E' (Temperature sensors faulty. Replace sensor).
Triggered by fault code E20.
Engineer: Go to section 'E' (Temperature sensors faulty. Replace sensor).
Triggered by fault code E28.
Diagnostic checklists from engineer-submitted Baxi faults, with step-by-step checks and safety notes.
The Baxi 800 boiler intermittently heating without a fault code can be attributed to several common issues, including low system pressure,…
The Baxi 100HE displaying an 'Ignition Lockout' fault, with no heating or hot water and no noises, indicates the boiler has failed to…
The Baxi 824 Combi 2 displaying fault code E.04.10 indicates that the burner has failed to ignite after four attempts.
Common questions from engineers and homeowners about the Baxi Duo-tec 40 Combi ErP.
Parts referenced in the manufacturer brochure for routine service and repair.
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Specifications on this page are extracted from the manufacturer brochure. Always cross-check against the latest datasheet before commissioning or quoting. Last updated 28 June 2026.