Worcester
The Worcester Greenstar 29 CDI Classic ErP is a 29 kW condensing combi boiler with 92% seasonal efficiency and ErP A/A ratings for heating and hot water.
The Worcester Greenstar 29 CDI Classic ErP is a wall-hung condensing combi boiler designed for domestic heating and hot water provision in the UK. This appliance operates on both natural gas and LPG, offering a versatile solution for various property types. It is part of the Greenstar CDi Classic range, known for its robust design and comprehensive feature set. This page provides technical specifications, fault codes, and maintenance guidance for heating professionals and homeowners.
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Full technical specifications extracted from the manufacturer brochure. Empty sections are hidden.
Pipes can be run below the boiler or alternatively up behind the boiler.
Artificially softened water must not be used to fill the central heating system.
The Worcester Greenstar 29 CDI Classic ErP (GC number 47-406-65) is a condensing combi boiler providing a maximum central heating output of 30 kW and a domestic hot water output of 30.9 kW. This appliance achieves a seasonal efficiency of 92% and holds an ErP A-rating for both heating and domestic hot water, with an XL hot water profile. It features a preheat function for domestic hot water, maintaining a temperature range of 40-60°C. Physical dimensions are 760 mm high, 440 mm wide, and 360 mm deep, with a dry weight of 47.5 kg. The unit incorporates safety features such as overheat and frost protection, flame failure detection, and a pressure relief valve. Control compatibility extends to FX/Greenstar Sense controls and the FW 100, supporting weather and load compensation strategies.
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/worcester/42cdi-classic-erp#fault-a1 to jump straight to the entry.
| Code | Meaning | Details |
|---|---|---|
| A1 | Pump has run dry or pump has stalled/seized. Show causes & actionsEngineer action Check for water leaks. Free the pump or replace. | Details |
| A7 | Hot water NTC sensor defective. Show causes & actionsEngineer action Check: - hot water NTC sensor - connecting lead for circuit breaks/short circuits. | Details |
| A8 | Break in communication to FX/Sense controls. Show causes & actionsEngineer action Check electrical connections. | Details |
| b1 | Code plug not detected. Show causes & actionsEngineer action Insert code plug correctly, test and replace if necessary. | Details |
| C6 | Fan speed too low. Show causes & actionsEngineer action Check: fan lead and connector, and fan; replace as necessary. | Details |
| E2 | CH flow NTC sensor defective. Show causes & actionsEngineer action Check CH flow NTC sensor and connecting lead. | Details |
| E9 | Safety temp. limiter in CH flow has tripped. Show causes & actionsEngineer action Check: - system pressure, - safety temp. limiters, - pump operation, - fuse on pcb, bleed appliance. | Details |
| EA | Flame not detected. Show causes & actionsEngineer action Is gas cock turned on? Check: - gas supply pressure, power supply, - igniter electrode and lead, - ionisation sensing electrode and lead, - flue duct and CO2 level. | Details |
| F0 | Internal error. Show causes & actionsEngineer action Check electrical connector contacts, programmer interface module ignition leads are not loose; replace pcb if necessary. | Details |
| F7 | Flame detected even though appliance switched off. Show causes & actionsEngineer action Check: - electrode assembly, - dry pcb. - Flue clear? | Details |
| FA | Flame detected after gas shut off. Show causes & actionsEngineer action Check: - gas valve; resistance, coil 1 = 190 Ω, coil 2 = 390 Ω - wiring to gas valve. Clean condensation trap and check electrode assembly. Flue clear? | Details |
| Fd | Reset button pressed by mistake. Show causes & actionsEngineer action Press reset button again. | Details |
Patterns that group across the manufacturer's fault-code table. Each entry links to the full code listing further down the page.
Engineer: Check for water leaks. Free the pump or replace.
Triggered by fault code A1.
Engineer: Check: - hot water NTC sensor - connecting lead for circuit breaks/short circuits.
Triggered by fault code A7.
Engineer: Check electrical connections.
Triggered by fault code A8.
Engineer: Insert code plug correctly, test and replace if necessary.
Triggered by fault code b1.
Engineer: Check: fan lead and connector, and fan; replace as necessary.
Triggered by fault code C6.
Diagnostic checklists from engineer-submitted Worcester faults, with step-by-step checks and safety notes.
Frequent pressure drops on a Worcester Bosch Greenstar boiler typically indicate a leak within the sealed system, a faulty pressure relief…
The Worcester Greenstar CDi is a condensing combination boiler.
The Worcester Greenstar 12i System displaying a "Heat exchanger overheat" fault code indicates the boiler's safety systems have activated…
The Worcester Greenstar 12i System displaying an 'Ignition lockout' fault indicates that the boiler has attempted to ignite but failed to…
Common questions from engineers and homeowners about the Worcester 42CDi Classic ErP.
Parts referenced in the manufacturer brochure for routine service and repair.
8716 116 067 08718 006 658 08711 004 168 08718 221 347 08722 963 858 08716 771 932 08716 107 044 08716 141 061 08716 107 887 08716 141 031 08718 221 728 08718 224 344 08716 115 754 08714 500 081 08716 106 685 08716 108 212 08737 703 196 08715 505 883 08716 106 845 08716 106 847 08714 500 087 08710 103 153 08716 106 431 08716 106 445 08710 506 267 08716 111 253 08716 111 252 08716 771 932 0We hold the Worcester 42CDi Classic ErP manual — and every other UK boiler and heat pump brochure. Sign up and pull any model up from your phone, on the job.
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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.