DISCHARGE-MAX on a Heliotherm Basic Comfort air split: Discharge (hot gas) maximum temperature limit exceeded
Short answer
On a Heliotherm heat pump, DISCHARGE-MAX means: Discharge (hot gas) maximum temperature limit exceeded. 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: Discharge (hot gas) maximum temperature limit exceeded.
Part involved: Discharge MAX error.
Likely causes:
- Refrigerant deficiency/leak.
- Control settings cause refrigerant circuit oscillation.
- Sensor defective.
- Control output X16 HGT defective.
Is it safe?
Switch the heat pump off at its isolator and call an engineer.
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Fault clearance function in the controller main menu (web control 321 manual p.27, intended for the Heliotherm competence partner).
What you can check
- Note the error text shown on the controller and contact your Heliotherm competence partner (manual: the heat pump should be shut off and checked by a trained specialist).
- Check the outdoor evaporator is not blocked by leaves, snow or debris.
What the engineer will check
- Leak-check and recharge.
- Check dsi settings.
- Check/replace discharge sensor.
- Check control input/output X16; replace controller if needed.
Who to ask for: heat pump / refrigeration (Heliotherm competence partner).
Certification: F-gas certification for refrigerant work.
What you might notice
Sources
- Heliotherm Installation Instructions Air Split Heat Pump Basic Comfort Series (Version 1.0, 28.03.2019) - via ManualsLib 3389544 ↗ · Version 1.0 · page 35 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026