H70 on a Dimplex LA MI inverter outdoor air-to-water: Backup heater overload protection (OLP) activated or disconnected
Short answer
On a Dimplex heat pump, H70 means: Backup heater overload protection (OLP) activated or disconnected. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Backup heater overload protection (OLP) activated or disconnected.
Part involved: Backup heater overload protector (OLP).
When it shows: During backup heater operation, no power to heater or OLP open circuit for 60 s.
Likely causes:
- Faulty power supply connector.
- Faulty connector connection.
- Faulty OLP.
- Faulty main water PCB.
- Underlying: air lock/poor flow or excessive inlet temperature.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: unknown.
Manual reset: Clear via control panel per Dimplex article (method shown as image).
What you can check
- Note the code and contact the installer or Dimplex service.
What the engineer will check
- Isolate the heat pump from mains before any work.
- Check OLP X-2511030 continuity.
- Check water flow/air.
- Check main water PCB.
Who to ask for: heat pump service engineer / heating engineer.
Certification: Electrical competence (Part P / qualified electrician) for work inside control panels.
What you might notice
Sources
- GDHV Help Centre article: i have h70 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