Heat pumps · Error codes · Warmflow
E06Warmflow · Zeno R290 air source heat pump AS01-R290/AS02-R290/AS03-R290
E06 on a Warmflow Zeno R290 air source heat pump AS01-R290/AS02-R290/AS03-R290: Excess Temp. Diff. Between Inlet & outlet
Short answer
On a Warmflow heat pump, E06 means: Excess Temp. Diff. Between Inlet & outlet. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Excess Temp. Diff. Between Inlet & outlet.
Part involved: water flow / water temperature.
Likely causes:
- There is not enough flow in the heating circuit.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
- Note the exact code shown on the controller (a photo helps) and report it to your installer or the manufacturer's service line.
- Check the heat pump's supply breaker/isolator at the consumer unit is on (do not open any casing).
- Check the heating system pressure gauge reading (if one is fitted) and tell your engineer if it is below the level set at commissioning; do not attempt to refill unless you have been shown how.
What the engineer will check
- Check the plumbing circuit for blockages or air, valves are open and the operation of the circulating pump.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer (manufacturer training recommended).
What you might notice
Sources
- Warmflow High Efficiency Variable Speed Air Source Heat Pumps A-Series AS01-R290 / AS02-R290 / AS03-R290 - User, Installation & Service Instructions, Guarantee (9009049 Rev D) ↗ · 9009049 Rev D · page 57 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026