Mitsubishi Electric air‑to‑air heat pump lauded by Stiftung Warentest as German install errors risk €50k damage

Mitsubishi Electric’s M‑Series air‑to‑air heat pump (split system MSZ‑RZ25VU + MUZ‑RZ25VUHZ) was named test winner by Stiftung Warentest in its May 2026 review of split‑type climate units. The system achieves a seasonal performance factor (SCOP) of up to 5.3 for heating and a SEER of up to 11.7 for cooling, uses the natural refrigerant R290 (propane), and is praised for its compact installation, inverter technology and suitability for both new builds and retrofits.

Separately, German heat‑pump experts warn that incorrect placement of any heat‑pump unit can cause severe damage and repair costs of up to €50 000. Recommended practices include shielding the unit from heavy rain and hail, locating it on the wind‑protected side of the house, mounting it at least 50 cm above ground (higher in flood‑prone areas), and ensuring unobstructed airflow to avoid noise complaints and efficiency losses.