SAV Commissioning Modules – How low can you go?

Ian Green, SAV Project Manager

A recent BSRIA study on fan coil systems using Commissioning Modules showed significant time-savings compared to traditional systems with commissioning valves on individual terminal units.

  • 28% saving on installation time
  • 43% saving on flushing horizontal mains pipework
  • 23% saving on flushing fan coil unit circuits
  • 44% saving on commissioning

SAV Commissioning Modules for Ultra Low Flow and standard flow hydronic systems

For quick, easy and accurate compliance with CIBSE Code W and the BSRIA Commissioning Guide – whatever the flow rate!

Tackling ultra-low flows

As buildings have become better insulated, with lower space heating demands, variable volume hydronic heating systems have become much more common.
The result is that commissioning engineers often find themselves dealing with ultra-low flows (<0.015 l/sec), where the flow rates are too low to measure accurately and consistently with standard flow measurement devices.

“Specifiers are required to identify an appropriate commissioning method for ultra-low flow system designs.”

– CIBSE Code W

To address this issue, SAV Systems has introduced Ultra Low Flow Commissioning Modules to its FloCon range, using patented valve technology.

SAV FloCon commissioning module which is pre-fabricated and tested off site. Designed for quick installation, accurate commissioning, easy maintenance and efficient pumping systems.

These modules overcome the problems of ultra-low flows by connecting groups of terminal units to a single, compact manifold that includes a differential pressure control valve (DPCV). The module then acts as a ‘control centre’ for commissioning, enabling flow measurement by subtraction – one of the methods recommended in the latest revisions
to CIBSE Code W (see below).

Designing systems with ultra-low flows can make a valuable contribution to reducing energy consumption and carbon emissions. However, such designs bring their own challenges.


How to deal with ultra-low flow rates.


Ultra-low flow module

SAV Ultra Low Flow Commissioning Modules facilitate the subtraction method of commissioning, one of the methods approved in the CIBSE Commissioning code W 2010 – water distribution systems.

The subtraction method, which can reduce commissioning times in both ultra-low flow and standard flow hydronic systems, is as easy as 1, 2, 3:

  • The flow through all of the terminal units connected to the commissioning module is measured to obtain a combined flow rate.
  • When one terminal unit is isolated, the flow rate through the remaining terminal units is still high enough to measure.
  • The difference between isolated terminal unit and combined flowrate of all terminal units is equivalent to the flow rate of the unit that was isolated.

Commissioning modules

A Commissioning Module essentially acts as a distribution ‘hub’ for a group of terminal units (typically up to seven) and enables commissioning to be carried out from the location of the module. Commissioning Modules are typically pre-fabricated and pre-insulated offsite under factory conditions and pre-tested before delivery to site.

Each module incorporates all of the valves required for commissioning, including 2-port actuated control valves and a differential pressure control valve to ensure that all 2-port control valves operate with excellent authority.

In addition to the time-savings, Commissioning Modules offer a number of other significant benefits, including:

  • Benefits of pre-fabrication
  • More effective use of skilled operatives on site
  • More precise measurement of ultra-low flows
  • Supplied in insulated box with vapour-sealed penetrations
  • No need to disturb insulation during commissioning
  • Facilitates use of flexible pipework
  • More flexible solution for end client


How to minimise pump energy consumption in pipework systems.


SAV Commissioning Modules can be used in conjunction with ‘remote sensor’ pump control, delivering higher efficiencies than those achieved with constant flow systems.

Using remote sensor control, the pump speed is controlled such that the pressure differential across the pump reduces towards the design pressure differential across the most remote pressure controlled sub-branches (or modules). Differential pressure sensors, wired back to the BMS or pump, are required across the selected sub-branches/modules.

Variable speed pump control

Used in conjunction with properly designed variable speed pump control, modules can achieve energy savings in the range of between 65 -70% relative to traditional constant flow systems (source BSRIA Guide BG12/2011). The bar chart below summarises the potential energy savings attributable to modular based designs for a typical system.


How to address the problem of dirt settlement in pipes carrying ultra-low flow rates.


copper multilayerSAV’s AluFlex flexible piping systems are available down to 14mm nominal diameter (10mm internal diameter) pipes to help increase water velocity.

AluFlex flexible piping systems

SAV’s AluFlex piping systems are ideal for use with SAV Commissioning Modules, enabling faster and more reliable installation with no requirements for elbows or bends. Connections are made with Pressfit fittings, saving even more time.

  • Connection is only required at the ends.
  • Faster installation, fewer connections, no elbows or bends.
  • Assists compliance with BSRIA guidelines for reducing installation times.
  • Fewer connections reduces the risk of leaks.
  • Easy to fit, with no requirement for specialist skills.
  • Robust design, resistant to rough handling on site.
  • Rated for temperatures up to 95degC and a working pressure of 12 bar
  • Life expectancy of 50 years, full guarantee for 10 years.
  • Gas-tight against oxygen, reduced risk of corrosion.


FloCon Module Installations

SAV Systems is proud to have supplied Flocon commissioning modules to a number of prestigious buildings and businesses throughout Britain. SAV always aims to deliver innovative solutions to the benefit of clients, consultants and contractors.

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University of Liverpool, Central Teaching Labs

“The SAV solution offers better more accurate control of differential pressure and easier, faster commissioning – a sixth of every floor at 30 St Mary Axe, could be balanced and finely tuned from a single point.”

– Dave Gatwood, Project Manager, Hills Mechanical ​







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30 St Mary Axe

“The benefits at the commissioning stage have been remarkable.

There were zero problems in a 125,000 ft2 building!

Our commissioning engineers describe the Modules as

“a dream to work with” and all their figures were within the design set margins.”

– Stuart Bareham, Waterman Building Services

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Bishopsgate, Central London

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One Hyde Park, Central London

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New Cannon Street Tube Station building

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Harvey Nichols Department Store,
Central London