Heat pumps · Error codes · Warmflow
Heating-flow-rate-too-lowWarmflow · Zeno G-Series ground source heat pump GS08/GS16/GS03
Heating-flow-rate-too-low on a Warmflow Zeno G-Series ground source heat pump GS08/GS16/GS03: Heating flow rate too low or blocked
Short answer
On a Warmflow heat pump, Heating-flow-rate-too-low means: Heating flow rate too low or blocked. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Heating flow rate too low or blocked.
Part involved: water flow / water temperature.
Likely causes:
- The heating flow rate has dropped below the minimum threshold.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
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
- Fully purge the system of air (common in new installations).
- Check for blockages in filters, valves etc.
- Check the system pressure hasn't dropped.
- Ensure heating pump is functioning correctly.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer (manufacturer training recommended).
What you might notice
What owners and engineers report
1 owner and engineer report mentions this.
- No heating on the Zeno G-Series ground source heat pump GS08/GS16/GS03: 1 report
Sources
- Warmflow High Efficiency Variable Speed Ground Source Heat Pumps G-Series GS08 / GS16 - User, Installation & Service Instructions (v6) ↗ · v6 · page 59 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026