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Heat pumps · Error codes · Alpha Heating Innovation
E188Alpha Heating Innovation · Alpha Hydro 5/8/12/16 R32 monobloc (with Pre-Plumb 200)

E188 on an Alpha Heating Innovation Alpha Hydro 5/8/12/16 R32 monobloc: Request with temperature out of range: A request is made with the outdoor temperature exceeding the operating limits; system does not start until within limits

Short answer

On an Alpha Heating Innovation heat pump, E188 means: Request with temperature out of range: A request is made with the outdoor temperature exceeding the operating limits; system does not start until within limits. The heat pump stops until the fault clears or is reset.

Reviewed 23 September 2026 · 1 source

What it means

The manual says: Request with temperature out of range: A request is made with the outdoor temperature exceeding the operating limits; system does not start until within limits.

Part involved: outdoor temperature.

Likely causes:

  • A request is made with the outdoor temperature exceeding the operating limits; system does not start until within limits.

Is it safe?

Does the heat pump stop?Yes
SeverityFault — clears by itself when the condition goes

The heat pump stops until the fault clears or is reset.

What you can check

  • Note the code and any text shown on the display/controller.
  • Check the heat pump isolator and consumer-unit breaker are on.
  • Wait for outdoor temperature to return within operating limits.

What the engineer will check

Who to ask for: heat pump engineer.

Sources

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026