In this article, you’ll find the five most common fault codes for the Rendamax R3456 EVO commercial boiler, what each code means and the steps required to resolve the issue.
Please note that any work carried out on a commercial boiler must only be undertaken by a qualified Gas Safe registered engineer. If you require an experienced engineer who specialises in Rendamax boilers, please contact us to arrange a site visit. Our team is also available to provide technical support and advice whenever you need assistance.
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Common Rendamax R3456 EVO Fault Codes
| Fault Code | Definition | Quick Checks | Causes | Solutions |
| 110 | Flow Temperature Sensor Safety Lockout | Reset boiler, Inspect flow temperature sensor connection, Check wiring for damage or loose plugs, Check sensor is properly fitted, Verify system pressure & circulation | Faulty flow NTC sensor, Loose/damaged wiring, Corroded connector, Poor circulation causing false readings, PCB input fault | Reconnect or repair wiring, Replace faulty flow temperature sensor, Restore proper water circulation, Replace PCB is sensor circuit faulty |
| 128 | Flue Gas Temperature Too High | Reset boiler, Check flow sensor connection, Inspect wiring/plug for damage or corrosion, Verify sensor is firmly seated in pocket/pipe, Check system pressure is correct, Confirm circulation pump is running | Faulty flow temp sensor, Loose or damaged wiring, Corroded or wet connector, Poor water circulation/airlock, Blocked filter or valve restricting flow, PCB input fault | Reconnect/repair sensor wiring, Replace faulty flow sensor, Restore proper system circulation, Clean filters/strainers, Replace PCB if sensor circuit is defective |
| 217 | Fan Speed/Fan Proving Fault | Reset boiler, Check fan starts during ignition sequence, Inspect fan wiring & connectors, Check flue & air intake for blockages, Check condensate drain is not blocked, Listen for unusual fan noises | Faulty fan motor or speed sensor, Loose or damaged wiring/plug, Blocked flue or air intake, Condensation restriction affecting airflow, PCB fan control fault | Repair or reconnect wiring, Clear flue/air intake restrictions, Replace faulty fan assembly, Replace PCB if fan control signal is faulty |
| 160 | Air Pressure Switch/Fan Proving Fault | Reset boiler, Check fan starts & runs normally, Inspect air pressure switch tubes, Check flue or air intake for obstructions, Inspect condensate trap/drain for blockages, Check wiring to air pressure switch & fan | Faulty air pressure switch, Blocked or water-filled pressure tubes, Fan not operating correctly, Flue/air intake restriction, Condensate blockage affecting air flow, Wiring/connector fault | Clear or replace pressure tubes, Repair wiring/connectors, Replace faulty air pressure switch, Clear flue/condensate restrictions, Replace fan if not running correctly |
| 131 | Gas Pressure/Gas Safety Circuit Fault | Reset boiler, Check gas supply is on, Confirm other gas appliances work, Check boiler gas isolation valve is open, Inspect gas pressure switch wiring/connector, Check condensate & air intake are clear | Low or no gas supply pressure, Gas isolation valve closed or partially closed, Faulty gas pressure switch, Loose/damaged wiring to safety circuit, Gas valve not operating correctly, External gas supply issue | Restore gas supply and open valves fully, Repair wiring/connector issues, Replace faulty gas pressure switch, Gas pressure test & adjustment by engineer, Replace gas valve is not operating correctly |
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