Heat pumps · Error codes · Dimplex
S20Dimplex · WPM heat pump manager platform (error-code grouping)
S20 on a Dimplex WPM heat pump manager platform: Low pressure: pressure is below the heat pump's permissible low pressure values
Short answer
On a Dimplex heat pump, S20 means: Low pressure: pressure is below the heat pump's permissible low pressure values. 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: Low pressure: pressure is below the heat pump's permissible low pressure values.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: Automatic.
What you can check
- Check the outdoor unit is not blocked by snow/debris.
What the engineer will check
- Investigate cause if block recurs frequently.
What you might notice
Sources
- Dimplex WPM Touch heat pump manager - Operating instructions for users and specialists (Order no. 452117.66.02-EN, WPM3.13 / Display 1.15) ↗ · 452117.66.02-EN FD 0302 · page 56 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026