HP1 on a Kensa heat pump: High refrigerant pressure in discharge gas pipe (P5)
Short answer
On a Kensa heat pump, HP1 means: High refrigerant pressure in discharge gas pipe (P5). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 4 sources
What it means
The manual says: High refrigerant pressure in discharge gas pipe (P5).
Part involved: P5 discharge pressure / load circuit.
When it shows: Error level per manual: Fault.
Likely causes:
- Load-side flow restriction (often with FLH1/FLC1), load pump failure, T1 probe failure (E1).
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: unknown.
What you can check
- Note the code shown on the controller/LED; check the heat pump isolator and consumer-unit breaker are on; check thermostat/timer settings.
What the engineer will check
- Follow Kensa fault table actions: Load-side flow restriction (often with FLH1/FLC1), load pump failure, T1 probe failure (E1). Check load pump, load flow and restrictions, T1 probe; check refrigerant pressures.
Who to ask for: Refrigeration engineer (F-gas certified) / Kensa technical support.
Certification: F-gas Category I (refrigerant circuit work); MCS-certified GSHP installer.
What you might notice
Sources
- Kensa Evo Heat Pump Installation manual ↗ · V32 · page 50 · Reviewed 23 September 2026
- Q80 Series Heat Pump Operational Manual ↗ · Version 2 · page 23 · Reviewed 23 September 2026
- Shoebox Heat Pump Operational Manual (User Manual) ↗ · Version 8 · page 26 · Reviewed 23 September 2026
- Kensa Shoebox NX heat pump Installation manual ↗ · V12 · page 40 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026