Heat pumps · Error codes · Dimplex
S21Dimplex · WPM heat pump manager platform (error-code grouping)
S21 on a Dimplex WPM heat pump manager platform: Operating limit: the heat source temperature is below the heat pump's operating limit
Short answer
On a Dimplex heat pump, S21 means: Operating limit: the heat source temperature is below the heat pump's operating limit. The heat pump keeps running with some functions stopped.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Operating limit: the heat source temperature is below the heat pump's operating limit.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Information only |
| Engineer needed? | No |
The heat pump keeps running with some functions stopped.
Resetting itself: Automatic when heat source recovers.
What you can check
- No action - informational.
What the engineer will check
The manual does not list the engineer’s checks for this code.
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