Pressurisation Unit SPU 150 MIDI

Pressurisation Units

The Stuart SPU Midi range of digital pressurisation units represent the next generation of automatic filling and pressure maintenance solutions for sealed heating and chiller systems.

Capable of filling a system from empty and then monitoring and maintaining the design fill pressure in sealed systems, Stuart SPU Midi units are exceptionally easy to install and commission and are housed in a compact and robust enclosure suitable for either floor or wall mounting.

Units are available with one (duty), or two (duty-standby) premium quality Stuart peripheral pumps featuring all brass pump heads and continuously rated induction motors.

Utilising an unique microprocessor controller and pressure transducer, these systems feature an intuitive and easy to use menu based control system, self-diagnostic functions, configurable volt-free contact alarm connections and a Building Management System Modbus interface.

Key Features:

  • Advanced digital control system
  • Automated system fill and pressure maintenance
  • Compact design
  • Wall or floor mounted
  • Inlet and outlet configurable for left or right hand side connection with flexible hoses (supplied)
  • 3.5 and 4.1 bar pressure options
  • Single (duty) or twin pump (duty-standby) configurations
  • 8 litre tank capacity
  • High recovery water tank fill valve 12 ltrs/min @ 1 bar
  • WRAS compliant Category 5 backflow protection, type AB air gap, weir overflow and warning pipe
  • 2 year guarantee
  • Patent application submitted


Technical Specification

Product code 46723
Guarantee 2 year
System capacity Up to 300,000 litres
Mounting Wall or floor mount
Pumps 1
System fill mode  
Pump control system  
Control interface  
Dry run protection  
Noise (Db(A)) 62
Fluid category CAT 5 (type AB air gap with weir)
IP rating IPX2
Maximum head (nominal closed valve) 4.1 bar (410 kPa)
Maximum flow 20 l/min
Maximum inlet pressure (tank fill valve) 7 bar (700 kPa)
Maximum working pressure 6 bar
Ambient air temperture 4 °C - 40 °C
Water tank
Usable capacity 8 litres
Fill rate 12 l/min
Cold water inlet (flexible hose) 15 mm compression
Cold water outlet (flexible hose) 15 mm compressioon
Overflow (compression fitting) G ¾ (19 - 23 mm diameter pipe)
Break tank Polyethylene
Front cover Acrylic capped ABS
Pump head Brass
Pump impeller Brass
Pump type Peripheral
Duty rating Continuous (S1)
Motor type Induction (thermal trip, auto reset)
Power supply/phase/frequency 230/1/50
Current (full load) 2.4 Amps
Power consumption 545 Watts
Fuse rating 5 Amps
Power cable (pre-wired) 1.5 metres
Depth 270 mm
Width 415 mm
Height 504 mm
Empty weight 13.4 Kg
Filled weight 23.4 Kg

Product Variants
Part no Description
46719 SPU 130 MINI
46720 SPU 230 MINI
46721 SPU 135 MIDI
46722 SPU 235 MIDI
46723 SPU 150 MIDI
46724 SPU 250 MIDI
46725 SPU 180 MAXI
46726 SPU 280 MAXI