LED-11-forward on an Ideal Heating Logic Air: Serial communication error (serial forward transfer error) - outdoor unit cannot receive hydraulic unit signal
Short answer
On an Ideal Heating heat pump, LED-11-forward means: Serial communication error (serial forward transfer error) - outdoor unit cannot receive hydraulic unit signal. 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: Serial communication error (serial forward transfer error) - outdoor unit cannot receive hydraulic unit signal.
Part involved: hydraulic unit interface PCB / interconnection.
When it shows: Outdoor unit cannot properly receive serial signal from hydraulic unit for 10 s or more.
Likely causes:
- 1. Connection failure 2. External cause (noise).
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 or fault message shown on the controller/Halo and when it appeared; check the heat pump's isolator and consumer-unit breaker are on. If the fault clears after the installer-approved restart via the controller and does not return, note it for the next service; if it returns, call an engineer.
What the engineer will check
- Reset power; check wiring/connectors in control unit; check L-N 198-264 V; check terminal 2-3 signal swings AC30-130 V; replace controller (interface) PCB if abnormal.
Who to ask for: Heat pump engineer; casing removal only by persons competent with R32 (A2L); refrigerant-circuit work requires Cat I/II F-gas certification (I&M p.75 warning).
Certification: F-gas Cat I/II for refrigerant work; electrical work by competent person.
Sources
- Maintenance Manual LOGIC AIR 8-10 Air/water heat pump Monobloc system (U0753484_2451_EN_1) ↗ · U0753484_2451_EN_1 · page 11 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026