Short answer
Lochinvar EcoSword water heaters show a letter-and-number error code: C codes are control errors, E codes temperature errors, F codes fan, air proving, ignition, flame and ionisation errors, and S codes temperature sensor faults. Lockout errors flash and need a reset. Blocking errors clear themselves once the cause is fixed. Src and Ano are warnings.
Lockout vs blocking
Lochinvar's manual splits displayed errors into two groups. Lockout errors (the code and backlight flash) need a manual reset once the cause is removed. Blocking errors (code shown steadily) reset automatically. A blocking error that lasts 20 hours or more becomes lockout C02.
Ignition and flame codes
F04 (ignition), F05 (flame) and F19 (three unsuccessful ignition attempts) are the codes we see most often. Usual causes are a closed gas valve, low inlet pressure, the wrong CO₂ setting, a damaged flame probe or a problem with the flue or air supply. F07, F08 and F11 mean a flame signal was detected when there should be none. These faults involve the gas valve and must be investigated, not just reset.
Other Lochinvar models
This table covers the EcoSword only. Lochinvar's Charger and EcoCharger manuals use their own code lists. We have not published those because we could not confirm them line by line. Call us with the code on screen and we'll check it against the manual for your unit.
Before you reset
A single reset after a power cut or a known one-off event is reasonable. Repeated resets are not: many commercial controls count resets and lock out further (for example a 'too many resets' code), and resetting a flame or gas valve fault over and over can mask a dangerous condition. If a lockout returns, isolate the appliance and call a Gas Safe registered engineer with the relevant commercial competence.
Lochinvar EcoSword error and warning codes
| Code | Meaning | What to check |
|---|---|---|
| C02 | Control error — error message from the controller (lockout) | — |
| C03 | Control error (blocking) | — |
| C04 | Control error (blocking) | — |
| C05 | Control error (blocking) | — |
| E01 | Temperature error (blocking) | — |
| E03 | Temperature error (lockout) | — |
| E05 | Control error (lockout) | — |
| F01 | Control error (blocking) | — |
| F02 | Fan error — fan does not run at correct speed (lockout) | — |
| F03 | Air proving switch error — switch closed when fan is not running (lockout) | — |
| F04 | Ignition error (lockout) | — |
| F05 | Flame error (lockout) | — |
| F07 | Ionisation error — ionisation measured after the gas control valve was closed (lockout) | — |
| F08 | Ionisation error — ionisation measured before the gas control valve was opened (lockout) | — |
| F09 | Temperature error (lockout) | — |
| F11 | Ionisation error — ionisation after the gas control valve has closed (blocking) | — |
| F19 | Supply voltage error — three unsuccessful ignition attempts (blocking) | — |
| F21 | Air proving switch error — switch not closed while fan runs during post purge (lockout) | — |
| S02 | Sensor error — open circuit, sensor 1 of the temperature sensor (blocking) | — |
| S03 | Sensor error — open circuit, sensor 2 of the temperature sensor (blocking) | — |
| S12 | Sensor error — short circuit, sensor 1 of the temperature sensor (blocking) | — |
| S13 | Sensor error — short circuit, sensor 2 of the temperature sensor (blocking) | — |
| Src | Warning — service is required (pre-set service interval exceeded) | — |
| Ano | Warning — anode protection is not working | — |
Source: Lochinvar EcoSword installation, commissioning, user & maintenance instructions (section 12.1). Codes and meanings can differ between versions and control software — always check the manual for your exact appliance.
Figures are typical for UK natural gas. The current edition of the relevant IGEM standard and the manufacturer's instructions always take precedence on site.
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