1 on a Haier heat pump: In water temp.sensor (Twi) failure
Short answer
On a Haier heat pump, 1 means: In water temp.sensor (Twi) failure. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the Super Aqua Monobloc (R32, AU..FYCRA(HW))
The manual says: In water temp.sensor (Twi) failure.
Part involved: temperature/pressure sensor.
On the Super Aqua Split (R32, AW..SSCHA/SNCHA + HU..WAMNA)
The manual says: in water temp.sensor (Twi) failure.
Part involved: temperature/pressure sensor.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: yes.
What you can check
- Note the code shown on the controller and the unit model numbers (on the rating plate label) before contacting your installer.
- Check the heat pump's breaker/isolator at the consumer unit is on; do not open any casing.
- Check the controller display is lit; a single power cycle at the isolator may be tried only if your installer or manual allows it.
What the engineer will check
- Follow the manufacturer's troubleshooting flowchart for this code.
- Check sensor connector and wiring.
- Measure sensor resistance against the manual's sensor table.
- Replace sensor or PCB as indicated by the troubleshooting flowchart.
Who to ask for: Heat pump engineer.
Certification: Heat pump installer competence; F-gas / flammable-refrigerant (R290/R32) handling competence for any refrigerant-circuit work.
What you might notice
Sources
- ATW Service Manual (Super Aqua monobloc) SYJS-03-2019 REV.A ↗ · SYJS-03-2019 REV.A · page p.73 (printed; PDF p.75) · Reviewed 23 September 2026
- Operation & Installation Manual - Air-to-Water Heat Pump Indoor Unit HU062WAMNA / HU102WAMNA (No. 0150554179) ↗ · 0150554179 · page p.17 (printed; PDF p.19) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026