Heat pumps · Error codes · Alpha Heating Innovation
A466Alpha Heating Innovation · Alpha Hydro 5/8/12/16 R32 monobloc (with Pre-Plumb 200)
A466 on an Alpha Heating Innovation Alpha Hydro 5/8/12/16 R32 monobloc: Low voltage error of DC circuit
Short answer
On an Alpha Heating Innovation heat pump, A466 means: Low voltage error of DC circuit. 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: Low voltage error of DC circuit.
Part involved: outdoor unit.
Likely causes:
- Check input voltage and power connections.
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 input voltage and power connections.
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 40 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026