702 on an alpha innotec heat pump: Low pressure stop. Reset autom.: Air/water units only: low pressure in the refrigerant circuit has responded; heat pump restarts automatically after some time
Short answer
On an alpha innotec heat pump, 702 means: Low pressure stop. Reset autom.: Air/water units only: low pressure in the refrigerant circuit has responded; heat pump restarts automatically after some time. 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 pressure stop. Reset autom.: Air/water units only: low pressure in the refrigerant circuit has responded; heat pump restarts automatically after some time.
When it shows: Air/water units only: low pressure in the refrigerant circuit has responded; heat pump restarts automatically after some time.
Likely causes:
- Refrigerant leak.
- Pressostat switching point.
- Defrosting problem.
- Outdoor temperature below minimum.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: yes.
Manual reset: automatic.
What you can check
- Note the error number and text shown on the Luxtronik display.
- The controller resets this automatically after the stated time - wait for the automatic restart before calling.
- Acknowledge the message by pressing the rotary pushbutton for about 7 seconds (as the Luxtronik manual permits); if the same error reappears, contact your installer or ait customer service with the error number.
- Check the heat pump breakers/isolator at the consumer unit are on (do not open any casing).
- Air source units: check the outdoor unit/air inlet and outlet are not blocked by snow, ice, leaves or debris.
What the engineer will check
- Check heat pump for leakage.
- Check pressostat switching point.
- Check defrosting and T-outdoor min.
Who to ask for: F-gas certified refrigeration / heat pump engineer (R290 flammable-refrigerant competence for propane units such as LWD).
Certification: F-gas certification (R407C/R410A units); flammable refrigerant training for R290 units.
What you might notice
Sources
- Operating manual Luxtronik heating and heat pump control Part 2 (UK) 83055400lUK - 2.1 ↗ · 83055400lUK 2.1 · page 52 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026