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 |
|---|---|
| Severity | Fault — 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
- Alpha Pre-Plumb 200 - Pre-plumbed cylinder with Hydro heat pump - Installation and Servicing Instructions (06-23) ↗ · Pre-Plumb 200 instructions 06-23 · page 37 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026