Major projects from Aberdeen University to the new Stock Exchange building in London have turned to the Commissioning Module as an effective solution that not only saves energy,but also speeds system installation and commissioning.

It's a success story based on a simple premise - one that applies for everything from children to fan coils - small groups are easier to control than large ones.

Variable speed

System designers now have to come to terms with variable flow water distribution systems. Pumps that operate at full power only are no longer acceptable, because by varying the speed of the pump to match system demand, pump energy consumption can be significantly reduced.

In fact,the cube law relationship between pump speed and energy consumption means that even small reductions in pump speed can lead to dramatic reductions in energy consumption.

Estimated pump energy savings of between 60-70% have been predicted for typical building heating and cooling applications.

However,designers face the challenge of utilising the undoubted energy saving potential of variable speed pumps,while avoiding problems elsewhere in the system.

In a traditional approach large,flanged Differential Pressure Control Valves (DPCV’s) are used to compensate for variations in the main branch pressure caused by the movement of control valves,or variations in pump speed.Two-port valves are used to control and shut off against the pressure controlled by the nearest upstream DPCV.

Where long distribution lines to fan coils etc are involved high differential pressure may be required to overcome system pressure – and achieving good valve authority as specified is almost impossible!

Valve authority should be greater than 0.23 but this is difficult to

reach if the pressure drop controlled by the DPCV is too great – figures of 0.8 – 1.3 bar are typical. So, designers face the double challenge of saving energy without increasing capital costs and

risking embarrassing operating problems.

Solution

The Commissioning Module solution ‘modularises’ the system in such a way that groups of terminal units (with a combined maximum output of 46kW heating or 25kW cooling per group)can share facilities –including a smaller,less expensive DPCV where required. By utilising this manifold-based modular solution, with all necessary controls (including DPCV)located in a pre-insulated box and using a flexible plastic-coated aluminium pipe such as ‘Alupex’for low pressure drop run-outs, all the design issues can be resolved with no increase in overall system cost.

Organising smaller sub-systems each centred around a Commissioning Module enables one compact DPCV to be shared by up to six terminal units with a maximum loading of 11.6kW heating and 6.3kW cooling per terminal – a highly cost efficient ratio. Moreover, because the DPCV’s are located close to the terminals, the pressures they control are relatively low – typically 0.2 – 0.5 bar. Smaller,cheaper actuators can be used for the 2-port valves and that crucial good valve authority can be achieved every time.

The key features of the Module include:

A large bodied strainer to remove circulating system debris before it can cause blockages in terminal units, regulating valves or control valves.

Flexible,plastic-coated aluminium pipe,which can be installed in single lengths between the manifold and terminals with a 60% labour saving compared to rigid pipes.

A central flushing by-pass and drain so that each terminal can be flushed and cleaned from a single location–no need for looping out.

A central air vent so that the entire arrangement including terminals can be vented from a single point.

A return manifold with optional balancing valves (or on/off two port

valves) incorporated on each port.

A single DPCV (when required) to maintain a constant differential pressure between flow and return manifolds.

Pre-insulated casing

The latest Commissioning Modules feature all key components including multi-port manifold, air vent and isolation valves already housed in a pre-insulated galvanised steel casing.Insulating the casing means there's no need to attempt vapour sealing of individual components - seals that are virtually impossible to achieve and must be broken the first time access is required!

This ‘box’ - no bigger than a standard fan coil unit - can be simply

and quickly located in the ceiling or floor void. Location is totally

flexible so easy access for maintenance is assured. Connecting up the flexible polyethylene-coated aluminium pipe is literally a matter of minutes and the Commissioning Module is ready for action.

Two-port control valves within the module are hard wired to a terminal at one end of the Commissioning Module for easy on site connection into the control system. A wide range of control options including inbuilt pulsed meters for ‘intelligent’ control is also available.

Easy access to all components is achieved via a hinged lid retained by two sturdy catches - and a retaining chain in the case of units intended for overhead mounting.

Additional benefits

As the name implies Commissioning Modules were originally developed to speed the commissioning process – and they do! Practical experience,however,has revealed a whole host of additional benefits not least of which is easy access for maintenance. In hotels, hospitals and exclusive apartment buildings discretion can sometimes be as important as efficiency!

Albion Riverside - an 11 storey luxury apartment building on the river Thames between the Albert and Battersea bridges is a fine example of the technology in action.

Designed by Foster & Partners,with Ove Arup & Partners appointed as building services consultants,Albion Riverside comprises a total of 183 one to four bedroom apartments and 14 penthouses.The structure imitates the curve of a Nautilus shell - increasing the river frontage and providing each apartment with a wonderful view.

Air conditioning is supplied by more than 600 fan coil units installed by Meica Building Services. Commissioning was carried out with the aid of SAV Commissioning Modules, each of which houses the controls for a group of fan coils in an enclosure located in the hallway ceiling. Maintenance can be carried out without disturbing the privacy of any apartment.

Every SAV Module is also linked to an energy meter,so that individual apartments can be accurately billed for the energy consumed.

Balancing flow rates

The latest SAV 767 Commissioning Modules incorporate the new Cimberio Double Regulating Valve.Cimberio is one of the few companies in the world to manufacture both isolation valves and double regulating valves and a wealth of experience has been poured into the new design.

Balancing of the system flow rates is achieved by opening or closing the Double Regulating Valve - the body ring simultaneously raising or lowering the vertical indicator to give an easy to read setting. Unlike other valves of this type, the indicator scale can be read from any angle.

Once the desired flow rate has been established,the unit can be locked in position via an Allen key located in the valve handle. The

metal-to-metal thread enables the valve setting to be rigidly locked,

so it can be closed and re-opened to its exact setting with great accuracy.

The design of the Cimberio Double Regulating Valve at the heart of the new Commissioning Modules has been tested by BSRIA in water conditions featuring high levels of air and dirt.The valves were found to perform extremely well, a result attributed to the compact internal layout and clean lines,which offer little opportunity for entrapment of air or dirt.

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