Low Carbon Energy Solutions for Building Services

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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.

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 inside).

SAV Commissioning Modules - How low can you go?

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

Issue 35

SAV Commissioning Modules -Technology you can rely on

Ian Green, SAV Project Manager

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

www.sav-systems.com

www.sav-systems.com

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.

CHALLENGE 1:

How to deal with ultra-low flow rates.

SOLUTION:

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:

1. The flow through all of the terminal units connected to the commissioning module is measured to obtain a combined flow rate.

2. When one terminal unit is isolated, the flow rate through the remaining terminal units is still high enough to measure.

3. The difference between isolated terminal unit and combined flow rate 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

Ultra-low flow module.

SAV Systems HVAC Commissioning

Product Brochure

Flocon - Ultra-low flow and standard flow headers

CHALLENGE 2:

How to minimise pump energy consumption in pipework systems.

SOLUTION:

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.

CHALLENGE 3:

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

SOLUTION:

SAV’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.

BSRIA Guide BG12/2011 Design of Energy Efficient Pumping Systems

Released in 2011 with recommendations on how to minimise pump energy consumption in pipework systems.

CONSTANT FLOW

Pump speed constant Pump speed controls maintain constant pressure

across pump

Pump speed controls maintain pressure at most remote DPCV

VARIABLE FLOW

4 Port Valves

Modules + 4 Port Valves

2 Port Valves + DPCV’s

DPCV Modules

Rela

tive

pum

p en

ergy

con

sum

ptio

n (%

)

Copper Multilayer

Nom. Diameter

Flow Rate (l/s) at 0.5m/s

Nom. Diameter

Flow Rate (l/s) at 0.5m/s

15 0.072 14 0.039

22 0.158 16 0.057

28 0.262 20 0.100

For further information contact:SAV Systems, Scandia House, Boundary Road, Woking, Surrey GU21 5BXTel: +44 (0)1483 771910 Web: www.sav-systems.com E-mail: info@sav-systems.com

www.sav-systems.com

“The SAV solution offers

more accurate control of

differential pressure and easier,

faster commisioning - 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

University of Liverpool, Central Teaching Labs.

Bishopsgate, Central London. New Cannon Street Tube Station building.

One Hyde Park, Central London. Harvey Nichols Department Store, Central London. London Stock Exchange.

SAV Commissioning Module

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

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.