Digital Pressurisation Unit

MIKROFILL SPU MAXI microprocessor controlled single pump pressurisation units are purpose designed with both the specifier and installer in mind.


Suitable for maintaining pressure in large domestic and commercial sealed heating systems, chilled water systems, refrigeration units and industrial cooling systems. SPU 180 MAXI units are exceptionally easy to install and commission and are housed in a compact and robust enclosure suitable for floor or wall mounting.


They feature the latest in microprocessor technology together with the tried and tested components featured in the original Maxi range.


We listened to your feedback and have added improvements to the Maxi, which include:

  • Adding a back panel for additional structural stability and protection.
  • Adding feet for improved stability, particularly on uneven surfaces.
  • Modifying the door catch to provide better guidance when closing.


BIM Object Ready

This product is now BIM Object Ready! Click here to access the BIM Object data for this product.

BIM-OBJECT 2 Year Warranty UKCA-CE
Stuart Pressurisation Unit SPU 180 MAXI
Key Features
  • Suitable for sealed systems of up to 300,000 litres
  • Single (Duty) pump option
  • 8.5 bar cold fill pressure
Technical Specification
Product Code 46725
Warranty 2 years
Conformity certification UKCA / CE
Sealed system capacity Up to 300,000 litres
Mounting Floor or wall mount 
Pump control system
Intelligent control interface
System fill mode
Dry run protection
Break tank Polyethylene
Enclosure Powder coated steel
Maximum fill pressure 8.5 bar (at 3 l/min)
Maximum flow (at 0.5 Bar) 38 l/min
Maximum inlet pressure - tank fill valve 7 bar / 700 kPa
Maximum working pressure 10 bar
Ambient air temperature Min 4 oC / Max 40 oC
Relative humidity 95 % non-condensing
Min./Max. water temperature Min 4 oC / Max 23 oC
Water tank
Usable water capacity 18 litres
Inlet valve Float valve
Fluid category CAT 5 (type AB air gap with weir)
Cold water inlet 1 ¼”
Cold water outlet 1 ¼”
Overflow G ¾ (20 mm diameter pipe compression fitting)
Number of pumps 1
Pump mode Duty
Pump type Peripheral
Motor type Induction, auto-reset thermal trip
Duty rating Continuous (S1)
Pump head and impeller Brass
Power supply (Vac/Ph/Hz) 230 V a.c. / 1 / 50 Hz
Power consumption - P1 680 Watts
Current - full load 5.6 Amps
Fuse rating 8 Amps
Alarm output True
Enclosure protection IPX2
Width 470 mm
Depth 440 mm
Height 645 mm
Weight - including fittings 33 Kg
Weight - filled 51 Kg
Compare Models
Description Part Number Maximum fill pressure Number of pumps
MIKROFILL SPU 140 MAXI 47502 4.0 bar (at 1 l/min) 1
MIKROFILL SPU 180 MAXI 46725 8.5 bar (at 3 l/min) 1
MIKROFILL SPU 240 MAXI 47503 4.0 bar (at 1 l/min) 2
MIKROFILL SPU 280 MAXI 46726 8.5 bar (at 3 l/min) 2