1 L FAN High voltage 2 N FAN 3 4 N FUSED 5 L FUSED 6 N FUSED
The A5 error code on Warmhaus boilers indicates 1 l fan high voltage 2 n fan 3 4 n fused 5 l fused 6 n fused.
Warmhaus A5 means: 1 l fan high voltage 2 n fan 3 4 n fused 5 l fused 6 n fused. The usual causes are fan motor failure (seized bearings or burned windings), fan speed sensor fault or wiring fault between fan and pcb. You can safely reset the boiler once — if A5 returns, do not keep resetting. A qualified heating engineer should diagnose the root cause.
What Does A5 Mean
The A5 code is shown by the boiler’s control board when it detects 1 l fan high voltage 2 n fan 3 4 n fused 5 l fused 6 n fused. The boiler then stops instead of continuing to run in that condition: the code is the appliance reporting a problem, not proof that the boiler is broken.
| What you see on the boiler |
|---|
| The display shows A5 and the boiler stops until the fault is cleared |
Common Causes
Causes documented in 1 technical sources.
| Cause |
|---|
| Fan motor failure (seized bearings or burned windings) |
| fan speed sensor fault |
| wiring fault between fan and PCB |
| air pressure switch fault (stuck open or closed) |
| blocked flue or air intake restricting airflow |
| condensate blocking the siphon or trap |
Safety Warning
A5 involves electrical or pressure-related components. Do not attempt repairs without proper qualifications. Ensure the boiler is electrically isolated before any inspection. If you notice water leaks, unusual sounds, or pressure anomalies, contact a qualified heating engineer immediately.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
Step-by-Step Diagnosis
1. Listen for the fan — it should start before ignition. If silent, check power supply to the fan motor. 2. Spin the fan manually (with power off) — if it feels stiff or gritty, the bearings are worn. 3. Check the wiring connections between the fan and PCB. 4. Test the air pressure switch — with the fan running, the switch should close. Disconnect and test with a multimeter for continuity. 5. Check the flue for blockages — inspect the full length including the terminal. 6. Verify the condensate trap is clear. 7. Measure the fan speed signal at the PCB (Hall sensor output)
How to Fix It
Restore mains power supply
replace blown fuse
repair or replace damaged wiring
ensure proper earth bonding
if voltage is unstable, fit a voltage stabiliser or investigate the mains supply
Refer to the Warmhaus service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
Diagnostic Tools
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Affected Models
Warmhaus models that can display fault code A5:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Warmhaus models | — | Possible |
Frequently Asked Questions
Restore mains power supply. According to the technical documentation, this is the first check on the list for A5.
A5 is not classified as a high-severity fault, so the boiler can be reset once. If A5 comes back, stop resetting: the underlying cause is still there and needs a qualified heating engineer.