Andrews E64 Fault Code: Causes, Fixes & Repair Costs
What does the Andrews E64 fault code mean?
The E64 code appearing on an Andrews water heater or boiler display is not a fault code that features in any publicly available Andrews Water Heaters documentation or widely recognised third-party fault code database. Andrews is primarily a commercial and industrial water heater manufacturer, and their fault codes are buried within model-specific IOM (Installation, Operation and Maintenance) manuals rather than general consumer guides. Because of this, the precise meaning of E64 depends entirely on your specific Andrews model. Based on how comparable commercial boiler systems use the E6x code range, E64 most likely relates to a temperature sensor fault, a flue or combustion sensor issue, or a fan-related problem — but this must be confirmed against your own unit's manual before any action is taken. Do not attempt any internal repairs: contact Andrews Technical Support or a Gas Safe registered engineer to get a verified diagnosis for your model.
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
- NTC temperature sensor fault Common
On comparable commercial boiler systems, codes in the E6x range most frequently point to a failed or out-of-range NTC thermistor — either on the flow, return, or flue circuit. A degraded sensor sends incorrect temperature readings to the PCB, which then triggers a protective lockout. This is the most probable interpretation of E64 if it follows the same convention as similar systems.
- Fan or flue pressure fault Common
Some E6x codes on commercial heating equipment relate to the fan assembly or the air-pressure differential switch that monitors flue draught. If the fan is running slowly, has failed, or the pressure switch is stuck or blocked, the control board may log this type of fault to prevent unsafe flue conditions.
- PCB or wiring fault Sometimes
A fault code can sometimes be triggered not by the component it nominally describes but by a wiring fault, corroded connector, or a failing PCB misreading a sensor signal. On older or heavily used commercial units this becomes increasingly likely and can cause intermittent or spurious fault codes.
- High-limit thermostat trip Sometimes
Andrews commercial systems include high-limit safety thermostats that cut the unit off if temperatures exceed safe thresholds. A sustained overheat event — caused by scale build-up, a failing pump, or restricted flow — can trigger sensor-range fault codes including codes in the E6x series.
- Unverified or model-specific code definition Rare
Because E64 does not appear in any publicly available Andrews documentation found at the time of writing, there remains a genuine possibility that on your specific model the code carries a unique meaning not covered by general E6x conventions. Until confirmed against your unit's IOM manual or via Andrews Technical Support, the true cause cannot be stated with certainty.
How to fix it
- Locate your Andrews model number and check the IOM manual DIY safe
Your model number is usually on a data plate on the front or side of the unit. Visit andrewswaterheaters.co.uk to download the correct IOM manual for your exact model. Search the fault code section for E64 — this is the only way to get a verified definition for your specific appliance.
- Contact Andrews Water Heaters Technical Support DIY safe
If you cannot find a manual or the code is not listed, call Andrews Technical Support directly. Have your model number and serial number to hand. They can confirm exactly what E64 means on your unit and advise on the appropriate response.
- Check that the gas supply to the building is on DIY safe
Before assuming an internal fault, confirm that the gas supply is live — check that other gas appliances in the building work normally. If there is a wider gas supply issue, contact your gas supplier rather than an engineer.
- Reset the unit once and observe DIY safe
If your Andrews unit has a reset button or procedure (described in your manual), you may attempt a single reset. Watch whether the fault returns immediately or after a short period of operation. Do not reset more than once or twice — repeated resets on a genuine fault can cause further damage or mask a safety issue.
- Do not open the casing or attempt internal inspection Gas Safe engineer
Any internal inspection — checking sensors, fan connections, the PCB, or wiring — must only be carried out by a Gas Safe registered engineer familiar with commercial Andrews equipment. Opening the casing yourself is unsafe and may invalidate any remaining warranty or service contract.
- Call a Gas Safe registered engineer with commercial boiler experience Gas Safe engineer
Given that E64 is likely a sensor, fan, or flue-related fault on a commercial unit, a Gas Safe engineer should attend to carry out a proper diagnosis. Make sure the engineer has experience with commercial water heaters and, ideally, Andrews or Rendamax equipment. Provide them with your model number and the fault code so they can prepare appropriately.
Parts you may need
- NTC flow or return temperature sensor · from £35
- Flue NTC sensor · from £45
- Fan assembly · from £150
- Air pressure differential switch · from £55
- PCB (model-specific) · 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 £150–£420, depending on the underlying cause.
Frequently asked questions
Why can't I find the Andrews E64 fault code listed anywhere online?
Andrews Water Heaters is primarily a commercial and industrial manufacturer, and their fault code definitions are published within model-specific IOM manuals rather than in general consumer boiler-fault databases. Unlike mainstream domestic brands such as Worcester Bosch or Vaillant, Andrews codes rarely appear on consumer-facing websites. Your best sources are the official Andrews website (andrewswaterheaters.co.uk) and their Technical Support team — both can give you a verified answer for your exact model.
Could E64 on my Andrews unit be a sensor fault?
Quite possibly. On comparable commercial heating systems, codes in the E60–E69 range frequently relate to NTC temperature sensors (flow, return, or flue), fan operation, or air-pressure monitoring. However, because E64 is not documented in any publicly available Andrews manual, this is informed reasoning rather than a confirmed fact. A Gas Safe engineer familiar with Andrews equipment will be able to read live diagnostic data and identify the faulty component precisely.
Is it safe to keep using my Andrews water heater while E64 is showing?
No — you should not continue to run the unit while a fault code is active. Andrews commercial systems are designed to lock out or reduce operation when a fault is detected, precisely to prevent unsafe conditions. Continuing to use the appliance risks further component damage and, depending on the underlying fault, could create a safety hazard. Switch the unit off and arrange for an engineer to attend.
How much will it cost to fix an Andrews E64 fault?
Once a Gas Safe engineer has diagnosed the fault, most repairs for sensor, fan, or pressure-switch issues on commercial Andrews units fall in the range of £150–£420 including labour and parts. Labour rates for commercial heating engineers typically run £55–£80 per hour on weekdays and £80–£100 on weekends or for emergency call-outs. If the fault turns out to involve the PCB or heat exchanger, costs can rise significantly — a PCB alone may be £180–£400 and a heat exchanger £400–£600 or more — at which point a full unit replacement may be worth considering.