Heat pumps · Error codes · Kensa
FLH1Kensa
FLH1 on a Kensa heat pump: Heating-mode load temperature differential T2-T1 greater than the low-flow differential
Short answer
On a Kensa heat pump, FLH1 means: Heating-mode load temperature differential T2-T1 greater than the low-flow differential. The heat pump keeps running.
Reviewed 23 September 2026 · 4 sources
What it means
The manual says: Heating-mode load temperature differential T2-T1 greater than the low-flow differential.
Part involved: Load pump / distribution flow.
When it shows: Error level per manual: Warning.
Likely causes:
- Low load pump speed, low load flow, restrictions in heating distribution (closed valves/actuators, air), incorrect low-flow differential setting.
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Warning |
The heat pump keeps running.
Resetting itself: n/a (warning).
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: Low load pump speed, low load flow, restrictions in heating distribution (closed valves/actuators, air), incorrect low-flow differential setting.
Who to ask for: Heating engineer / GSHP installer.
Certification: MCS-certified GSHP installer recommended; Kensa-trained.
What you might notice
Sources
- Kensa Evo Heat Pump Installation manual ↗ · V32 · page 51 · 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 41 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026