Underfloor Heating Single-Room Control Unit with Grundfos Circulator Pump

A compact, ready-to-install solution for adding water-based underfloor heating to individual rooms of up to 20 m², including bathrooms, extensions, conservatories and other small domestic spaces. Designed to connect to an existing radiator or central heating system, this single-room control unit provides comfortable, evenly distributed heat without the need for extensive system modifications or additional mounting brackets.

The unit incorporates a Grundfos UPM3 FLEX AS 25-70 130 high-efficiency circulator pump, featuring variable-speed PWM control, a maximum head of 7 metres and a rated energy efficiency index (EEI) of ≤0.20. A built-in thermostatic mixing valve blends and regulates the water temperature supplied to the underfloor heating circuit, helping maintain suitable operating temperatures and reduce the risk of floor overheating.

Coverage and Heating Performance

• Maximum coverage: Up to 20 m² with pipe spacing of 200 mm.

• Higher-output configuration: Up to 15 m² with pipe spacing of 150 mm.

• Maximum stated heat output: 3 kW.

• Application: Single-zone, water-based underfloor heating for small domestic areas.

Actual heating performance and achievable coverage depend on heat loss, floor construction, insulation, pipe layout, water temperature and the capacity of the existing heat source.

Key Features and Technical Benefits

1. Grundfos UPM3 FLEX AS 25-70 130 Circulator Pump

The integrated high-efficiency circulator pump provides controlled water circulation through the underfloor heating circuit. Its PWM (pulse-width modulation) control supports variable-speed operation to help match pump performance to system demand.

• Energy efficiency index (EEI): ≤0.20.

• Maximum head: 7 m.

• Power consumption: 2–52 W, depending on operating conditions.

• Compact 130 mm installation length.

• Designed for efficient circulation with reduced electrical consumption.

Energy savings depend on the system configuration, operating conditions and the pump used for comparison.

2. Integrated Thermostatic Mixing Valve

The thermostatic mixing valve regulates the underfloor heating flow temperature by blending hot water from the primary heating system with cooler return water.

• Helps maintain a suitable flow temperature for underfloor heating.

• Reduces the risk of excessive floor temperatures when correctly selected and installed.

• Supports more consistent heat distribution throughout the heated area.

• Enables underfloor heating to operate alongside a conventional radiator heating system.

Appropriate temperature settings and any additional floor-temperature protection should be selected according to the floor manufacturer's requirements and the overall system design.

3. Compatibility with Heating Systems

The unit is intended for integration with a suitable existing hydronic heating system. Potential heat sources include gas or oil boilers and appropriately designed renewable heating systems, such as air-source and ground-source heat pumps, solar thermal systems and certain solid-fuel installations.

Compatibility depends on the heat source, available water temperatures, hydraulic arrangement, system controls and manufacturer requirements. Additional controls or hydraulic separation may be necessary for some installations.

4. Integrated Components

The control unit combines the principal components required to regulate and circulate water through a single underfloor heating zone, including:

• Thermostatic mixing valve.

• Grundfos circulator pump.

• Flow and return connections.

• Isolation valves.

• Mounting kit.

The compact assembly is designed to simplify installation and reduce the space required for separate components. Connection sizes, included fittings and mounting requirements should be confirmed against the manufacturer's technical specification before installation.

5. Compact Installation

Designed for applications where installing a complete multi-zone underfloor heating manifold would be unnecessary or impractical, the unit offers a space-saving approach to single-room heating.

Its integrated components help reduce installation complexity and can minimise disruption when adding underfloor heating to an existing property. Suitability depends on access to the primary heating circuit and the availability of adequate installation space.

6. Efficient, Comfortable Heating

Water-based underfloor heating distributes warmth across the floor surface, providing comfortable radiant heat with less reliance on conventional radiators within the heated room.

When correctly designed and commissioned, the system can support efficient operation, lower-temperature heating and integration with compatible renewable heat sources.

Temperature Regulation and Single-Zone Control

The integrated mixing valve is designed to regulate the temperature of the water entering the underfloor heating circuit, helping deliver controlled, consistent heating from an existing primary heat source.

This arrangement is particularly suitable for individual rooms where dedicated underfloor heating is required without converting the entire property. The final installation should incorporate appropriate room-temperature controls, flow-temperature settings and any additional safety devices required by the system design.

Ideal Applications

This single-room underfloor heating control unit is suitable for projects such as:

• Bathroom and en-suite renovations.

• Small extensions and conservatories.

• Individual rooms being upgraded to underfloor heating.

• Targeted heating improvements in properties with existing radiator systems.

• Compatible low-temperature heating installations.

Product summary: A compact single-zone underfloor heating control unit incorporating a Grundfos UPM3 FLEX AS 25-70 130 circulator pump and thermostatic mixing valve, designed for water-based underfloor heating installations covering up to 20 m² under suitable design conditions.