44 on an Atlantic heat pump: Heat pump return temperature sensor error
Short answer
On an Atlantic heat pump, 44 means: Heat pump return temperature sensor error. 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 · 5 sources
What it means
On the Alféa Excellia / Excellia Duo (R410A split, 11-16, pre-A.I.)
The manual says: Heat pump return temperature sensor error.
Part involved: B71.
Likely causes:
- Temperature sensor short-circuit, open circuit, unplugged or faulty.
On the Alféa Excellia A.I. / Excellia Duo A.I. (R410A split, 11-16)
The manual says: Return sensor HP.
Likely causes:
- Short-circuit.
- Unplugged or disconnected sensor.
- Faulty sensor.
- Temperature sensor short-circuit, open circuit, unplugged or faulty.
On the Alféa Extensa A.I. / Extensa Duo A.I. R32 (split, 3-10)
The manual says: Return sensor HP.
Likely causes:
- Short-circuit.
- Unplugged or disconnected sensor.
- Faulty sensor.
- Temperature sensor short-circuit, open circuit, unplugged or faulty.
On the Alféa Extensa + / Extensa Duo + (R410A split, 5-16)
The manual says: Heat pump return temperature sensor error.
Part involved: B71.
Likely causes:
- Temperature sensor short-circuit, open circuit, unplugged or faulty.
On the Alféa Hybrid Duo (heat pump + integrated fuel-oil boiler)
The manual says: Heat pump return temperature sensor error.
Part involved: B71.
Likely causes:
- Temperature sensor short-circuit, open circuit, unplugged or faulty.
Is it safe?
On the Alféa Excellia / Excellia Duo (R410A split, 11-16, pre-A.I.)
| 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: 1.
On the Alféa Excellia A.I. / Excellia Duo A.I. (R410A split, 11-16)
| 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.
On the Alféa Extensa A.I. / Extensa Duo A.I. R32 (split, 3-10)
| 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.
On the Alféa Extensa + / Extensa Duo + (R410A split, 5-16)
| 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: 1.
On the Alféa Hybrid Duo (heat pump + integrated fuel-oil boiler)
| 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.
What you can check
- Note the error number/LED pattern shown and give it to your installer.
What the engineer will check
On the Alféa Excellia / Excellia Duo (R410A split, 11-16, pre-A.I.)
- Check sensor wiring and connector.
- Measure sensor resistance; replace if faulty.
Who to ask for: heat pump / electrical.
On the Alféa Excellia A.I. / Excellia Duo A.I. (R410A split, 11-16)
- Check the sensor's wiring.
- Replace the sensor.
Who to ask for: heat pump / electrical.
On the Alféa Extensa A.I. / Extensa Duo A.I. R32 (split, 3-10)
- Check the sensor's wiring.
- Replace the sensor.
Who to ask for: heat pump / electrical.
On the Alféa Extensa + / Extensa Duo + (R410A split, 5-16)
- Check sensor wiring and connector.
- Measure sensor resistance; replace if faulty.
Who to ask for: heat pump / electrical.
On the Alféa Hybrid Duo (heat pump + integrated fuel-oil boiler)
- Check sensor wiring and connector.
- Measure sensor resistance; replace if faulty.
Who to ask for: heat pump / electrical.
What you might notice
Sources
- alféa excellia duo Maintenance Document (U0546279_1738_EN_16) ↗ · U0546279_1738_EN_16 · page 68 · Reviewed 23 September 2026
- Alféa Excellia A.I. Installation manual (U0611757_1876_EN_14) ↗ · U0611757_1876_EN_14 · page 76 · Reviewed 23 September 2026
- Alfea Extensa A.I. R32 Installation manual (U0671217_2114_EN_11) ↗ · U0671217_2114_EN_11 · page 70 · Reviewed 23 September 2026
- alféa extensa + Installation and operating manual (doc 1734-10, 1734-EN) ↗ · 1734-10 · page 74 · Reviewed 23 September 2026
- alféa hybrid duo Installation and commissioning instructions (doc 1440-13) ↗ · 1440-13 · page 65 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026