7H-22 on a Daikin Altherma 4 H: Water flow requirement problem at space heating request or during Water pipe freeze prevention
Short answer
On a Daikin heat pump, 7H-22 means: Water flow requirement problem at space heating request or during Water pipe freeze prevention. 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: Water flow requirement problem at space heating request or during Water pipe freeze prevention.
Part involved: plate heat exchanger freeze protection.
When it shows: Minimum water flow requirement at space heating request is not reached.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: yes.
Manual reset: Automatic.
What you can check
- Read the full error code and sub-code shown on the user interface (Malfunctioning screen; press the help button for Daikin's long description) and note it, with the date/time, for your installer.
- Check the heating-system water pressure reading on the gauge/display: Daikin operation manuals ask users to check it is above 1 bar. If it is below that, report it to your installer (do not open the unit).
- Daikin documents this code as resetting automatically once the condition clears; if it keeps coming back, contact your installer.
- Do NOT bleed radiators while an error/malfunction symbol is displayed: Daikin operation manuals warn refrigerant may have leaked into the water circuit - ventilate and call your installer.
- If heating/hot water has stopped, the operation manual lets the user confirm on the Malfunctioning screen whether the backup/booster heater may take over as emergency heating (much higher running cost) until the installer attends.
What the engineer will check
- See Daikin service manual for this generation (not public).
Who to ask for: Heat pump installer / heating engineer.
Certification: None specific for water-side checks; MCS-certified installer recommended.
What you might notice
Sources
- Installer reference guide Daikin Altherma 4 H W EPSK/EPSKS + EPBX(U) (4P773390-1C) ↗ · 4P773390-1C · page 203 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026