H98 on a Dimplex LA MI inverter outdoor air-to-water: Refrigerant high pressure overload protection
Short answer
On a Dimplex heat pump, H98 means: Refrigerant high pressure overload protection. 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: Refrigerant high pressure overload protection.
Part involved: Outdoor high pressure sensor.
When it shows: During heating, pressure >= 4.0 MPa (40 bar) detected by HP sensor.
Likely causes:
- Insufficient water flow (most likely).
- Blocked strainer, air, low pressure, pump speed, 2-port valves.
- Faulty high pressure sensor.
- Faulty refrigerant PCB.
- Refrigerant overcharge after recent work.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: Clear via control panel per Dimplex article (method shown as image).
What you can check
- Check the heating system pressure gauge reads about 1.0-1.5 bar.
- Note the code and contact the installer or Dimplex service.
What the engineer will check
- Isolate the heat pump from mains before any work.
- Flow checks as H62.
- Gauge high side: trip below 40 bar indicates sensor/PCB fault (F-Gas).
Who to ask for: refrigeration / heat pump service engineer.
Certification: F-Gas (refrigerant handling) certification for any refrigerant-circuit work.
What you might notice
Sources
- GDHV Help Centre article: i have h98 error on my la mi heat pump what does this mean ↗ · GDHV article (modified 2023-02) · page n/a (web article) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026