Verified boiler fault code
Alpha 10 Fault Code (Evoke 28 and 33)
Primary system pressure low.
Safety disclaimer
Fault code summary
- Manufacturer
- Alpha
- Fault code
- 10
- Fault type
- Low pressure, Central heating
- Severity
- Not specified
- Reset
- Not specified
- Applicable models
- Evoke 28, Evoke 33
Quick answer
Primary system pressure low.
What does this fault code mean?
Primary system pressure low.
Common causes
- Primary pressure switch operated.
- Expansion-vessel pressure, system leak or pressure-relief issue.
Symptoms
This information was not provided in the verified manufacturer source.
What can the homeowner safely check?
- Read the pressure gauge; do not remove the casing.
Boiler reset information
Reset information was not provided in the verified manufacturer source. Do not repeatedly reset an unresolved fault.
When should I call an engineer?
Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.
Engineer diagnosis
- Assess system pressure, expansion vessel, leaks and pressure switch.
Applicable boiler models
Related fault codes
- 01 — Evoke 28 and 33
Ignition failure; flame not detected during the ignition sequence.
Read fault code - 02 — Evoke 28 and 33
Overheat boiler lockout.
Read fault code - 03 — Evoke 28 and 33
High flue temperature.
Read fault code - 04 — Evoke 28 and 33
Gas-valve electrical connection fault.
Read fault code - 05 — Evoke 28 and 33
CH flow sensor fault.
Read fault code - 06 — Evoke 28 and 33
DHW sensor fault.
Read fault code - 08 — Evoke 28 and 33
Maximum number of resets reached (five).
Read fault code - 16 — Evoke 28 and 33
Fan fault.
Read fault code
Manufacturer documentation
Alpha Evoke installation and servicing instructions10 | Primary system pressure low | Primary pressure switch has operated | Check expansion vessel pressure (1 bar); leak in system; expansion relief valve operated; primary pressure switch
Last verified
2026-09-12
Frequently asked questions
What does Alpha 10 mean?
Primary system pressure low.