Andrews E22 Fault Code: Causes, Fixes & Repair Costs
What does the Andrews E22 fault code mean?
The E22 code on an Andrews water heater most likely indicates an ignition or flame detection fault — part of the E2x family of error codes used across the Andrews range (ClassicFlo, HiFlo EVO, EcoFlo, FastFlo and similar models). When the appliance attempts to light, the integrated Honeywell control board either fails to confirm that a flame has been established, or detects a problem with the flame-sensing signal. After a set number of failed ignition attempts, the unit enters a safe lockout and holds the code on the display. Because Andrews does not publish full fault-code lists publicly, always cross-reference with your model's installation manual or Andrews technical support if the description below does not match your symptoms exactly.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Dirty or degraded flame-sensing electrode Common
The flame sensor rod sits in the burner flame and passes a tiny current back to the control board to confirm ignition. Over time the rod accumulates carbon deposits or the tip degrades, making the signal too weak for the board to accept. This is one of the single most common reasons an Andrews unit enters ignition lockout.
- Faulty or incorrectly gapped ignition electrode Common
If the spark electrode is cracked, heavily worn, or the gap to the burner head has changed through vibration or heat cycling, the unit may produce a weak or absent spark. The board then sees repeated failed ignition attempts and locks out with E22.
- Gas supply issue or gas valve not opening Common
If other gas appliances in the property are also losing supply, the meter may be in credit or the emergency control valve may be partly closed. Even with gas present, a gas valve that sticks or fails to open fully will starve the burner of fuel, causing every ignition attempt to fail.
- Restricted flue or blocked air intake Sometimes
Andrews water heaters need unobstructed airflow through the air intake and flue. Debris, bird nesting material, or a collapsed flue terminal can reduce combustion air or prevent safe exhaust extraction, both of which cause ignition failure or immediate flame dropout after lighting.
- Fan fault or air-proving switch failure Sometimes
The combustion fan must reach its correct speed before the control board will allow the gas valve to open. A worn fan motor, a failed Hall-effect sensor on the fan, or a faulty air-proving (differential pressure) switch can all prevent the ignition sequence from progressing, producing an E2x lockout.
- Faulty PCB or ignition lead Rare
If the control board is not generating the correct spark trigger signal, or a cracked ignition lead is losing the high-voltage pulse to earth, no spark will be produced even though all other components are sound. PCB faults can also cause the board to misread a good flame signal and lock out unnecessarily.
How to fix it
- Check that gas is available to other appliances DIY safe
Turn on a gas hob ring or check another gas appliance. If nothing lights, the problem is with the gas supply rather than the Andrews unit itself. Check your meter is in credit and that the emergency control valve on the gas meter is fully open (handle in line with the pipe).
- Check and restore boiler system pressure if applicable DIY safe
If your Andrews unit is part of a sealed heating system, look at the pressure gauge. It should read between 1 and 1.5 bar when cold. If it is below 1 bar, top it up using the filling loop and refer to the user guide for your specific model. Note: many Andrews water heaters are open-vented or direct-fired and do not have a filling loop — skip this step if yours has no pressure gauge.
- Check for a frozen condensate pipe in cold weather DIY safe
In temperatures below 0 °C, a plastic condensate pipe running outside the building can freeze solid, causing the appliance to lock out. If you can safely reach the pipe, thaw it by pouring warm (not boiling) water along its length or by applying a heat wrap. Once clear, attempt a reset.
- Reset the appliance once DIY safe
Press and hold the reset button (or turn the reset knob, depending on your Andrews model) as described in your user guide. Allow the unit a full ignition cycle — typically 30 to 60 seconds — before deciding whether it has lit successfully. If it locks out again immediately or within a short time, do not keep resetting; repeated resets without fixing the underlying fault can damage components and mask the true problem.
- Have a Gas Safe engineer clean or replace the flame-sensing electrode Gas Safe engineer
An engineer will remove the burner assembly, inspect the sensor rod for carbon fouling or tip erosion, and either clean it with a fine abrasive or replace it. This is one of the most cost-effective fixes for E2x lockouts and is often carried out during an annual service visit.
- Have a Gas Safe engineer inspect and test the ignition electrode and lead Gas Safe engineer
The engineer will check the electrode gap, look for cracks in the ceramic body, and test the ignition lead for continuity and insulation breakdown. Worn electrodes and cracked leads are straightforward, relatively inexpensive parts to replace.
- Have a Gas Safe engineer test the gas valve Gas Safe engineer
Using a gas analyser and pressure gauge, the engineer will verify that the valve opens correctly and delivers the right gas rate to the burner. A valve that is stuck, slow to open, or passing insufficient gas will require replacement — this is a notifiable gas-safety repair that must be carried out by a Gas Safe registered person.
- Have a Gas Safe engineer inspect the fan and air-proving switch Gas Safe engineer
The engineer will check fan speed, look for worn bearings, and test the differential pressure switch that signals the board when airflow is established. A faulty fan or switch that prevents the pre-purge cycle completing will cause repeated lockouts.
- Have a Gas Safe engineer test the PCB and consider replacement if all other components pass Gas Safe engineer
If electrodes, gas valve, fan, and flue all check out, the control board itself may be generating a false lockout or failing to produce a spark trigger. PCB diagnosis requires specialist test equipment; replacement is the usual outcome if the board is confirmed faulty.
- Call a Gas Safe registered engineer with Andrews commercial water heater experience Gas Safe engineer
If you have not already done so, book a Gas Safe registered engineer — ideally one familiar with Andrews or Honeywell-controlled commercial water heaters. Note down the full code as it appears on the display, the model number (usually on a data plate inside the front panel), and any pattern to when the fault occurs (e.g. first thing in the morning, after a period of inactivity). This information helps the engineer diagnose quickly and arrive with the right parts.
Parts you may need
- Flame-sensing electrode (Andrews compatible) · from £25
- Ignition electrode assembly · from £35
- Ignition lead / HT lead · from £20
- Gas valve (Honeywell or OEM equivalent) · from £220
- Combustion fan assembly · from £130
- PCB / Honeywell integrated control board · from £290
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £120–£380, depending on the underlying cause.
Frequently asked questions
Is E22 definitely an ignition fault on my Andrews water heater?
Andrews does not publish its full fault-code list openly, so E22 cannot be confirmed without consulting the manual for your specific model. That said, the E2x range of codes on Andrews appliances running Honeywell integrated controls is consistently associated with ignition and flame-detection faults. Check the data plate inside the front panel for your exact model, then call Andrews technical support (andrewswaterheaters.co.uk) or a Gas Safe engineer experienced with Andrews units if the description on this page does not match what your appliance is doing.
Can I fix Andrews E22 myself?
A handful of preliminary checks are safe for a homeowner: confirming gas reaches other appliances, topping up system pressure if the unit is on a sealed system and pressure is low, thawing a frozen condensate pipe in winter, and pressing reset once. Beyond that, every internal repair — cleaning or replacing electrodes, testing the gas valve, inspecting the flue or fan — must be done by a Gas Safe registered engineer. Andrews explicitly requires that all service work is carried out by qualified personnel.
How much will it cost to repair Andrews E22?
For the most common causes — electrode cleaning or replacement and related labour — most people pay in the region of £120 to £250 all in. If the gas valve needs replacing, expect £280 to £380 once parts and labour are combined. A PCB replacement is at the top of the typical range and can exceed £400 to £500 depending on the specific board and engineer's call-out fee, though this is a less common outcome. Getting an annual service (roughly £80 to £150) is the best way to catch electrode wear before it causes a lockout.
How do I stop Andrews E22 from coming back?
The most effective prevention is an annual service by a Gas Safe engineer familiar with Andrews units. During a service the engineer will clean or replace the flame sensor and ignition electrode, check gas pressure and combustion quality, and inspect the flue — addressing the root causes of E2x lockouts before they put the unit into lockout. Keeping the area around the air intake clear of debris and ensuring the flue terminal outside is unobstructed also reduces the risk of airflow-related ignition failures.