Wilo Star-Z 25/6 domestic hot water recirculation pump (180 mm)
- Application: DHW recirculation
- Q × H: up to 6.5 m³/h × 6.0 m
- Power / P1 max: 1×230 V / 115 W
- DN + PN: DN25 (G1½ (Rp1)), PN 10
Where Star-Z 25/6 is used
Bronze Star-Z 25/6 — higher-capacity DHW recirculation pump with 6 m head and 6.5 m³/h flow. For multi-family buildings, hotels, gyms with long DHW loops.
The pump handles water and water–glycol mixtures up to 50 % (viscosity impact to be accounted for). Control modes: 3 fixed speed steps (I/II/III). Liquid temperature range: +2 °C … +110 °C.
Technical specifications
| Parameter | Value |
|---|---|
| Model | Star-Z 25/6 |
| Manufacturer code | 4047573 |
| Connection | G1½ (Rp1) (DN25) |
| Max. working pressure (PN) | 10 bar |
| Max. flow (Q) | 6.5 m³/h |
| Max. head (H) | 6.0 m |
| P1 power | 50–115 W |
| Power supply | 1×230 V / 50 Hz |
| Enclosure class | IP44 |
| Energy Efficiency Index (EEI) | not applicable (DHW recirculation) |
| Control modes | 3 fixed speed steps (I/II/III) |
| Liquid T range | +2 °C … +110 °C |
| Port-to-port length | 180 mm |
| Weight | ~4.4 kg |
Sizing formula — quick calculation
Required flow rate: Q = P / (1.163 × ΔT), where P – heating load (kW), ΔT – supply/return temperature difference (°C).
Example: a 10 kW DHW system with ΔT 5 °C requires Q = 10 / (1.163 × 5) = 1.72 m³/h. Wilo Star-Z 25/6 fully covers for multi-family and commercial DHW loops systems.
When to choose Star-Z 25/6
- Single-family homes and small multi-family DHW loops
- Hotels, gyms, commercial premises with long DHW loops
- Systems where potable-water-rated housing (bronze / stainless) is required
- Renovation projects requiring a Wilo / Grundfos analog without piping rework
- Compatibility / replaces: Grundfos UPS 25-60 B / 25-80 B (bronze DHW analogs).
B2B delivery and logistics via Amegata.lt
- Next-day delivery across Lithuania (from Vilnius warehouse)
- Competitive B2B pricing — often below market average
- 30-day payment terms for verified companies
- Free engineering consultation on pump selection
Official Wilo catalogue: wilo.com
Frequently asked questions
What is the difference between Δp-c and Δp-v control modes?
Δp-c (constant pressure) keeps a fixed differential pressure across the system, better suited to underfloor heating or systems without thermostatic valves. Δp-v (proportional pressure) lowers the differential as flow drops, better for radiator systems with thermovalves.
Is it suitable for open-vented heating systems?
No — Star-Z 25/6 is designed for closed pressurised systems. Open-vented gravity-flow systems require a different pump type.
Does it work with glycol?
Yes, up to 50 % water–glycol concentration. Viscosity impact must be accounted for — real head typically drops about 10–15 % with 30 % glycol, and P1 power shifts accordingly.
What is the typical EEI class and why does it matter?
DHW recirculation pumps are exempt from EU Ecodesign EEI rules — 3-speed motors consume more than ECM units, but bronze / stainless housing properties matter more than EEI here.
What is the recommended installation position?
Horizontal rotor shaft, cable entry facing down or sideways. Vertical mounting is not allowed. Install a strainer/filter upstream — pumps do not tolerate welding slag or debris in new systems.
