S.176 on a Vaillant aroTHERM plus: External electrical power limitation is active The heat pump or the electric back-up heater is limited by the energy supply company
Short answer
On a Vaillant heat pump, S.176 means: External electrical power limitation is active The heat pump or the electric back-up heater is limited by the energy supply company. The heat pump keeps running.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: External electrical power limitation is active The heat pump or the electric back-up heater is limited by the energy supply company.
Part involved: Heat pump control (status/Live Monitor).
When it shows: External electrical power limitation is active The heat pump or the electric back-up heater is limited by the energy supply company.
Likely causes:
- Operating status reported by the heat pump control (not a fault in itself).
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Information only |
| Engineer needed? | No |
The heat pump keeps running.
Resetting itself: yes - status changes automatically with operating state.
Manual reset: not applicable.
What you can check
- Status only: the energy supplier/tariff lockout (e.g. off-peak switching) is interrupting the heat pump supply. Check any tariff time-switch/relay settings with your installer if this happens often.
What the engineer will check
- None required unless heating/hot water is not delivered; then review status history, settings and application limits.
Who to ask for: Vaillant-trained heat pump installer/engineer (MCS-certified installer).
Certification: MCS installer certification; Vaillant product training recommended.
What you might notice
What owners and engineers report
14 owner and engineer reports mention this.
- No heating on the aroTHERM plus (VWL ../6 A): 8 reports
- Keeps stopping / cutting out on the aroTHERM plus (VWL ../6 A): 6 reports
Sources
- uniTOWER (VIH QW 190/6 E) operating, installation and maintenance instructions ↗ · 0020291525_05 · page uniTOWER VIH QW 190/6 E 0020291525_05 p.57; VWZ MEH 97/6 hydraulic station 0020291544_03 p.49; aroTHERM split hydraulic station VWL ../5 IS 0020257319_05 p.54 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026