Pre Heat switch off temperature ATMO & PREMIX 30 - 75 55
The P27 error code on Warmhaus boilers indicates pre heat switch off temperature atmo & premix 30 - 75 55.
Warmhaus P27 means: pre heat switch off temperature atmo & premix 30 - 75 55. The usual causes are faulty or worn ignition electrode, cracked or dirty ignition lead or gas supply interruption or low gas pressure. You can safely reset the boiler once — if P27 returns, do not keep resetting. A qualified heating engineer should diagnose the root cause.
What Does P27 Mean
The P27 code is shown by the boiler’s control board when it detects pre heat switch off temperature atmo & premix 30 - 75 55. 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 P27 and the boiler stops until the fault is cleared |
Common Causes
Causes documented in 1 technical sources.
| Cause |
|---|
| Faulty or worn ignition electrode |
| cracked or dirty ignition lead |
| gas supply interruption or low gas pressure |
| blocked condensate drain preventing ignition |
| defective gas valve not opening |
| faulty PCB (printed circuit board) not sending ignition signal |
Safety Warning
P27 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. Note the exact error code and check the manufacturer's installation and service manual for specific guidance. 2. Check all visible wiring connections for security and condition. 3. Power cycle the boiler — switch off at the mains for 30 seconds, then switch back on. 4. If the fault recurs, check the fault history for related or recurring codes. 5. Inspect the boiler for any obvious signs of damage, leaks, or unusual sounds
How to Fix It
Clean or replace the ignition electrode and lead
clear any condensate blockage (pour warm water over frozen external pipe in winter)
reset the boiler after checking all components
if the gas valve is not opening, replace the gas valve (Gas Safe registered engineer required)
if the PCB is not sending ignition signal, replace the PCB. Important: all gas work must be carried out by a Gas Safe registered engineer
Refer to the Warmhaus service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
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Affected Models
Warmhaus models that can display fault code P27:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Warmhaus models | — | Possible |
Frequently Asked Questions
Clean or replace the ignition electrode and lead. According to the technical documentation, this is the first check on the list for P27.
P27 is not classified as a high-severity fault, so the boiler can be reset once. If P27 comes back, stop resetting: the underlying cause is still there and needs a qualified heating engineer.