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Closed circuits

The problem

Dirt, debris, swarf, welding splatter and mill-scale are all incorporated into closed circuit water systems during construction. The complexity of pipework design in modern buildings means that it is often impossible to remove all this contamination by pre-commission cleaning and flushing.

Suspended solids and sludge continue to accumulate in systems during their working life due to corrosion, hard water, system modification etc. Corrosion of mild steel typically produces sediment volumes of 10 to 100 times the volume of the original metal removed.

Heating systems typically make up at 1.5 to 2.5% of the system volume per week. For a 10,000 litre volume system in a hard water area this will lead to more than 3 kg of solids per year accumulating in the system.

Closed circuit systems rarely fail due to corrosion and leakage most failures are due to accumulation of sediment causing blockages, poor heat distribution or dissipation, boiler failure and valve failure.



Typical problems caused by dirt and debris

New buildings

  • Difficulty in establishing and maintaining system balance
  • Valves jamming and blocking
  • Noise
  • Pump seal failure

Existing buildings

  • Poor heat distribution
  • Blockages & lack of flow
  • Pump seal failure
  • Control valve failure
  • Noise
  • Boiler failure


  • Continuous filtration with no backwashing or flushing required.
  • Closed recovery system provides zero water loss, saving water chemicals and energy.
  • Suitable for a wide range of temperatures and pressures, including high temperature hot water and chilled water systems.
  • Easily installed to existing systems.
  • Independent of system operation and flow.

Compact packaged system for closed circuit systems

Compact sized unit complete with pump and controls provides a high flow filtration system with minimal space requirement.

The units are skid mounted which means they are readily manoeuvred into position with no site assembly or lifting equipment required.


The CSF Series units will remove metal oxides, precipitated hardness salts and other separable solids down to less than 20 micron on continuous re-circulation.

Closed Recovery Systems (CRS Units)

Used in conjunction with our CSF range of cyclone filtration systems, these units collect the filtered dirt from the filter purge discharge allowing purge fluid to be returned to the system thereby eliminating any water or fluid loss from the system. The filtered dirt is collected in re-usable fabric bags for disposal.

CRS closed recovery systems are recommended for systems where fluid loss from filter purge needs to be avoided such as: -

  • Brine systems
  • Glycol systems
  • Thermal fluid systems
  • Chemically treated systems
  • Medium and High Temperature hot water systems

Benefits of CRS units

  • Saves time
  • Saves energy
  • Saves chemicals
  • Saves money