Grundfos ALPHA1 25-40 180

The ALPHA1 25-40 180 is a low-head circulator pump from Grundfos’ ALPHA1 series, delivering 4 metres (40 kPa) of head pressure with a 180 mm flange-to-flange distance. Designed specifically for low-resistance systems such as underfloor heating, radiant slabs, and domestic hot water recirculation loops, this pump provides gentle, efficient circulation without the excessive pressure that can cause noise, water hammer, or valve damage. The 180mm flange makes it a direct replacement for older larger-format pumps in low-head applications.

Key Benefits

• Low Head (4m / 40 kPa): Ideal for underfloor heating and low-resistance systems – prevents uncomfortable water noise and system stress.

• 180mm Flange Distance: Direct replacement for older 180mm circulators from Grundfos UPS, Wilo, and other brands.

• Standard 25mm Connections: Direct fit for residential piping systems without requiring adapters.

• Simple 3-Speed Manual Control: No complex settings – just choose speed 1, 2, or 3.

• Energy Efficient: Consumes as little as 20W – significant savings over older pumps.

• Quiet Operation: < 45 dB – essential for underfloor systems in living spaces.

Performance Details
The ALPHA1 25-40 180 delivers a maximum head of 4 metres (40 kPa) and a maximum flow rate of 3 m³/h. The pump features simple 3-speed manual control:

The pump includes a manual air purge screw, status LED, and thermal overload protection.

Why Low Head (4m) for Underfloor Heating?
Many installers mistakenly use high-head pumps (6m or 8m) on underfloor systems. This causes:

• Uncomfortable water noise (velocity too high)

• Increased energy consumption (wasted electricity)

• Premature valve and manifold wear

• Potential water hammer damage

The ALPHA1 25-40 180 delivers exactly what underfloor systems need: high flow at low pressure – gentle, quiet, and efficient.

Applications & Usage

• Underfloor heating (wet systems) – Primary application

• Large-area radiant slab heating

• Radiant ceiling panels

• Domestic hot water recirculation (low-resistance loops)

• Chilled water cooling (radiant slab cooling)

• Solar thermal systems (low-pressure collectors)

• Heat pump distribution (low-resistance fan coils)

• Replacement for older UPS 25-40 180 pumps

ALPHA1 vs ALPHA2 (25-40 180): Which to Choose?

When to choose ALPHA1: You want a reliable, affordable replacement with simple operation.
When to choose ALPHA2: You want maximum energy savings (as low as 5W) and automatic optimization.

Why 180mm Flange for Underfloor Systems?
The 180mm flange distance is commonly found in:

• Older underfloor heating systems

• Larger mechanical rooms with manifold stations

• Systems originally installed with Grundfos UPS 25-40 180

• Commercial low-head applications

Durability & Reliability
Engineered for continuous operation:

• Stainless steel rotor can – corrosion-resistant

• Ceramic bearings – self-lubricating, wear-resistant (50,000+ hours)

• Thermal overload protection – automatic shutdown prevents dry-running damage

• Manual air purge screw – easy de-airing during installation

• Cast iron housing – durable for decades

• IP42 rating – protected against dust and dripping water

• Wet rotor design – self-lubricating, no maintenance required

Customer Value
For NPF Store customers installing or maintaining underfloor heating systems, the ALPHA1 25-40 180 is the professional’s choice for budget-conscious projects. It delivers exactly the right performance profile – low head, adequate flow – while cutting energy bills by up to 50% compared to older pumps. The 180mm flange distance makes it a direct replacement for many older circulators without pipe modification. Your underfloor system will be quieter, more comfortable, and more efficient.

4. Key Features

• ✅ 4m Head (40 kPa) – Optimized for low-resistance underfloor and radiant systems

• ✅ 180mm Flange Distance – Direct replacement for older larger-format circulators

• ✅ Standard 25mm Connections – Direct fit for residential piping systems

• ✅ 3-Speed Manual Control – Simple, predictable operation

• ✅ Flow Rate (3 m³/h) – Adequate for most underfloor zones

• ✅ Low Power Consumption (20-35W) – Energy efficient for continuous operation

• ✅ Permanent Magnet Motor – More efficient than older induction motors

• ✅ Manual Air Purge Screw – Easy de-airing during installation

• ✅ Status LED – Basic operation monitoring

• ✅ Thermal Overload Protection – Prevents damage from dry running

• ✅ Ceramic Bearings – Long service life (50,000+ hours)

• ✅ Ultra-Quiet Operation – < 45 dB – ideal for living spaces

• ✅ Wet Rotor Design – Self-lubricating, maintenance-free

5. Technical Specifications