UA-17 on a Daikin Altherma: Tank type problem
Short answer
On a Daikin heat pump, UA-17 means: Tank type problem. 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: Tank type problem.
Part involved: inter-unit communication / PCB combination.
When it shows: [E-05] is not set as 1, or [E-07] is not set correctly.
Likely causes:
- Faulty [E‑05] or [E‑07] setting.; Faulty hydro PCB.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: Power reset via outdoor unit.
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.
- 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
- Check for improper combination of the indoor unit and the water tank. See the combination table in the Databook for more information. ; | Troubleshooting ; Check the setting [E‑05] and [E‑07] via the user interface. . ; Perform a check of the hydro PCB. .
Who to ask for: Heat pump installer (Daikin-trained).
Certification: None specific; MCS-certified installer recommended.
What you might notice
What owners and engineers report
13 owner and engineer reports mention this.
- No heating on the Altherma: 7 reports
- Controller / thermostat problem on the Altherma: 6 reports
Sources
- Service manual Daikin Altherma 3 M EBLA/EDLA04~08E (ESIE22-09) ↗ · ESIE22-09 · page 78 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026