Heat pumps · Error codes · Alpha Heating Innovation
A109Alpha Heating Innovation · Alpha Hydro 5/8/12/16 R32 monobloc (with Pre-Plumb 200)
A109 on an Alpha Heating Innovation Alpha Hydro 5/8/12/16 R32 monobloc: Communication error due to incorrect address of interface board
Short answer
On an Alpha Heating Innovation heat pump, A109 means: Communication error due to incorrect address of interface board. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Communication error due to incorrect address of interface board.
Part involved: outdoor unit.
Likely causes:
- Check the address on the interface board.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
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.
What the engineer will check
- Check the address on the interface board.
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 38 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026