Grundfos Manifold Pump & Mixing Valve Unit

The Grundfos UPM3 FLEX AS 25-70 130 is one of the most widely specified UFH circulators in the UK. An Energy Efficiency Index (EEI) of 0.20 places it at the ErP benchmark level, cutting electricity use by up to 80 % versus conventional fixed-speed pumps. PWM Profile A and B control allows direct digital integration with smart heat pump and boiler controllers, while the front-accessible terminal box and mechanical de-blocking device simplify maintenance in confined spaces.

A precision brass (HPB57-3) 1" blending valve with a manual mixing core and thermosensitive element regulates the hot/cold ratio, delivering a stable supply temperature to ±1 °C across the full 35–60 °C operating range. Rated to 10 bar and 100 °C, it is compatible with all standard boilers and heat pumps and sized to support systems up to 250 m² / 20 kW.

The built-in temperature controller and dedicated sensor monitor the mixed supply water in real time, trimming the valve position to hold the setpoint precisely. This prevents thermal overshoot — critical for protecting timber and engineered-wood finishes — and reduces energy waste by ensuring the manifold never receives hotter water than needed.

Both pressure and temperature gauges are fitted as standard, giving an at-a-glance view of system status during commissioning and day-to-day operation. The unit also includes a dedicated air-vent port for straightforward bleeding during fill-up — no separate instruments needed.

A 1" bore handles significantly higher flow rates than a ¾" valve, suits multi-zone and larger floor areas, and its wider internal diameter minimises friction loss and pressure drop — allowing the UPM3 to run at lower speed, saving energy and reducing noise. The more robust brass construction also delivers longer service life under continuous duty.

The complete mixing unit is engineered specifically for manifold installation with a lightweight, wall-mountable bracket for a tidy fit in plant rooms and airing cupboards. The G 1½" connections on both pump and blending valve match standard UFH manifold ports for a direct, no-adapter installation. A 5-year blending valve guarantee and 2-year pump guarantee underpin long-term confidence.

The valve opens under electrical power and closes automatically by spring return when de-energised. This normally-closed, fail-safe design prevents unintended flow if power is lost, and ensures a clean shut-off whenever the zone thermostat is satisfied.

The SPST potential-free end switch directly signals the boiler or circulating pump, firing the heat source only when a zone is genuinely calling — saving fuel and reducing wear. The 1 m heat-resistant flying lead wires cleanly into standard wiring centres and programmers.

The powerhead can be removed and replaced in-situ without draining the system — a major time-saver on service calls. The integrated manual lever holds the valve open during filling, venting, or draining at commissioning.

Opening time is approximately 12 seconds under power; spring return takes around 6 seconds — fast enough to respond promptly to zone demand without water hammer. Low 6 W power consumption and a quiet synchronous motor mean no audible disturbance in occupied spaces.