The 7H Controller Fault

Posted on December 2, 2022

In todays video Jamie show us why this fault may be showing up and how to fix the problem.

The 7H fault—a dreaded occurrence among air source heat pump enthusiasts and technicians alike. When commissioning your system, encountering this fault is not uncommon, often stemming from errors within the system itself. Let’s delve deeper into understanding and troubleshooting this notorious fault.

The 7H Fault

  • Frequency of Occurrence: Approximately 80% of the time, the 7H fault arises due to system errors.
  • Automatic Reset: The system might reset itself, but it could take some time. Patience is key as pressing the reset button may not immediately resolve the issue.

Troubleshooting Steps for the 7H Fault

Checking Air Vents

  • Location: Ensure all automatic air vents, especially those at the highest points of the system, are open.
  • Ventilation Points: Check for air vents inside buffer vessels, low loss headers, outdoor units, hydro boxes, and integrated units.

Bypass Valve Configuration

  • Correct Setup: Verify that the bypass valve is configured properly.
  • Flow Rate Adjustment: Set the bypass valve one or two litres per minute above the minimum flow rate of your unit.

Hydro Box Installation Details

  • Critical Check: Two plugs on the pipework going in and out of the hydro box must be removed during installation.
  • Preventing Errors: Failure to remove these plugs can trigger a 7H error.

We hope this gives a clear understanding of what the 7H Fault is so if someone asks you can be the one to sort it!