E29 Boiler Fault Code: What It Means on Every Brand

The E29 fault code appears on 3 boiler brands — Alpha, Andrews and Ravenheat — and on all of them it points to the same kind of problem. The details still differ by brand (thresholds, sub-codes, reset procedure), so use the table below to jump to the page for your boiler.

Lockout — engineer likely 3 brands use this code

Which brand is your boiler?

The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.

Brand	What E29 means	Severity	DIY?
AAlpha	The E29 code on an Alpha boiler indicates a flue sensor fault. Full guide →	Lockout — engineer likely	No
AAndrews	The E29 code on an Andrews boiler indicates a flame-loss lockout. Full guide →	Lockout — engineer likely	No
RRavenheat	The E29 code on a Ravenheat boiler signals that the domestic hot water or central heating circuit has reached a dangerously high temperature. Full guide →	Lockout — engineer likely	No

E29 brand by brand

Alpha E29

The E29 code on an Alpha boiler indicates a flue sensor fault. The boiler's control board is unable to receive a valid signal from the sensor that monitors conditions in the flue — the pipe that carries combustion gases safely out of your home. Because this sensor is a key safety component, the boiler locks out rather than risk operating without reliable flue monitoring. Note that the closely related E28 code points to a problem with the flue itself (such as a blockage or installation issue), whereas E29 specifically flags a fault with the sensor or its electrical circuit.

Causes, fixes & costs for Alpha E29 → · All Alpha codes

Andrews E29

The E29 code on an Andrews boiler indicates a flame-loss lockout. Unlike a fault where the boiler fails to ignite in the first place, E29 means the boiler successfully established a flame but then lost it during operation — and has shut itself down as a safety measure. The control system detected that a safe, stable flame could not be maintained, so it locked out rather than continuing to attempt ignition. This is normal protective behaviour; the boiler is doing exactly what it should. The fault needs to be investigated and resolved before the boiler will fire again. Note that the precise trigger can vary between Andrews models (including commercial water heater ranges), so always cross-reference with your specific model's service manual or contact Andrews directly if you are unsure.

Causes, fixes & costs for Andrews E29 → · All Andrews codes

Ravenheat E29

The E29 code on a Ravenheat boiler signals that the domestic hot water or central heating circuit has reached a dangerously high temperature. The boiler's built-in safety system detects that water temperatures have climbed beyond their safe operating limit and triggers a lockout to protect the appliance and your home. The boiler will not restart until the underlying cause is identified and resolved — resetting without fixing the root problem will simply bring the fault back.

Causes, fixes & costs for Ravenheat E29 → · All Ravenheat codes

Frequently asked questions

Is the E29 fault code the same on every boiler?

Broadly, yes — on Alpha, Andrews and Ravenheat the E29 code points to the same class of fault, and the recommended response is similar. Model-specific details such as sub-codes and reset procedures still vary, so follow the page for your own brand.

Can I fix a E29 fault myself?

Not usually. On every brand listed, E29 points to a fault that needs a suitably registered engineer to diagnose and repair. A single reset to rule out a transient glitch is reasonable; repeated resets are not.

Who should I call about a E29 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.

General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.