high-flow-temperature-e1x-t1 on an IVT Greenline HE: The compressor stops because the flow temperature is too high for the heating circuit. Activated when the sensor shows a value which is 5K higher than the highest set point value for the circuit. The factory setting for the highest set point value is 60 °C for radiator type of circuit and 35 °C for underfloor type of circuit After hot water production, the alarm is delayed with 4 min
Short answer
On an IVT heat pump, high-flow-temperature-e1x-t1 means: The compressor stops because the flow temperature is too high for the heating circuit. Activated when the sensor shows a value which is 5K higher than the highest set point value for the circuit. The factory setting for the highest set point value is 60 °C for radiator type of circuit and 35 °C for underfloor type of circuit After hot water production, the alarm is delayed with 4 min. 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: The compressor stops because the flow temperature is too high for the heating circuit. Activated when the sensor shows a value which is 5K higher than the highest set point value for the circuit. The factory setting for the highest set point value is 60 °C for radiator type of circuit and 35 °C for underfloor type of circuit After hot water production, the alarm is delayed with 4 min.
Part involved: E1x.T1.
When it shows: The compressor stops because the flow temperature is too high for the heating circuit. Activated when the sensor shows a value which is 5K higher than the highest set point value for the circuit. The factory setting for the highest set point value is 60 °C for radiator type of circuit and 35 °C for underfloor type of circuit After hot water production, the alarm is delayed with 4 min.
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 - The sensor's value falls below the temperature for beginning of the heating demand.
What you can check
- Note the full alarm text including the component designation (e.g. E21.T6) - IVT asks for it when you contact the dealer. Lower the heating on the circuit. Check that the thermostat valves are open. Contact the dealer if the alarm recurs often. Check the heating-system pressure gauge is in the range given in the user guide - do not top up yourself unless you have been shown how; check radiator/underfloor valves and room thermostats are open.
What the engineer will check
- Investigate per the installer guide alarm description and operating data.
Who to ask for: heat pump engineer.
What you might notice
Sources
- Installer Guide Greenline HE C6-C11 E6-E11 1x230V (6 720 802 419 (2012/06) en) ↗ · 6 720 802 419 (2012/06) · page 6 720 802 419 p.68; 6 720 643 409 p.83; 6 720 643 415 p.28 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026