Building Up the Pressure?
As the demand for pressure boosting systems has continued its incessant rise in recent years so has the engineered sophistication of the pump solutions being supplied to meet the varied requirements for these units. These include water supply, irrigation systems, water treatment systems, packaged fire sets and units that deliver for the hugely diverse area of industrial applications.
Now a staple within the building services world, packaged pump sets are increasingly needed to ensure that there is sufficient water available to meet the demands of both a sophisticated and demanding audience for the immediate and future more condensed living and working environments.
Mixed use buildings
One recent development within the industry that has seen a huge increase in interest is mixed-use buildings. These buildings combine either all or some elements of: housing, employment, retail, leisure and community use – under one roof.
Developments like this offer many advantages and in particular have breathed new life into many city centre areas. The largest and best known in this country has been on the ongoing development in London’s Canary Wharf. Additionally there is a range of projects in Manchester, Birmingham and Liverpool that have also met the mixed-use criteria with many more developments at varying stages in the developmental pipeline.
One major aspect in their favour is that they offer a much greener and more convenient alternative to the suburban out-of-town housing options from previous decades and have been one of the few win/win scenarios for both town planners on the one-hand and businesses, retailers, leisure suppliers and home buyers on the other.
There are a number of reasons for this including the fact that these developments:
- Maximise the available space and key site locations in busy town centre locations.
- Breathe new life and a 24-hour lifestyle into areas that would previously have been closed outside of normal business hours.
- Create a sense of community spirit and identity in inner-city locations.
- Are greener, as everything is close by and cars are not needed as much (this can frequently mean that where households would have had two cars, they are now often only a single car household and even this is used much less than the average).
One interesting aspect of this type of development means that much more consideration needs to be given to all areas of pre-planning as there are many more factors to be considered in terms of getting the balance between residential and non-residential content and what facilities should be developed for that particular geographical location.
This then has spin-offs for the design of the building and how best to exploit aspects such as: scenic advantages, privacy, type of retail outlets and unit size, as well as looking at the other services, existing facilities and future plans for the immediate area.
Delivering the pressure
The demand for pressure boosting has grown consistently in recent years as a result of taller buildings, more condensed living, inconsistent site pressure and reduced mains pressure; this together with the need to reduce the plant room size into the smallest possible footprint due to space premium; has made the selection process much more complex.
There is an increasingly wide range of booster solutions available to building services specifiers – but how do you decide which system is best for your particular application?
Where do you start?
To make sure you are taking the correct factors into account when sizing a booster set the following areas should be included within the calculation.
Firstly the actual system configuration needs to be established taking into account the volume and position of water storage (e.g. basement, intermediate, rooftop). The next step is to define the actual flow. There are quite a few tools available to assist you with this calculation in a single-use building.
However this is a much more complex calculation in a mixed-use building and is an area where we suggest you should seek guidance from an experienced booster manufacturer like Grundfos Pumps in order to ensure the set will meet all the requirements for that particular solution as well as being as energy efficient as possible. One common error that is made at this stage is to size the set based on all the appliances running together at maximum demand – this is very rarely the case and will result in over-sizing.
Over sizing any booster set will result in a larger and therefore more expensive set being purchased than the system actually needs as well as it costing considerably more in energy terms over the course of its working life (Life Cycle Cost).
The next step is to define the consumption and load profiles which is another challenging aspect that needs to be undertaken to establish the appropriate stages in getting the best booster selection and will help to define how many pumps (or sets) are the ideal for the particular application.
The final step in the selection process involves determining the pumps duty; this is calculated based on the static height, friction losses and required end pressure.
Prior to final specification it is important to ensure that where the equipment footprint is a key aspect, that pumps such as those from the Grundfos CR vertical multi-stage families are selected. Additionally, in their variable speed form, they offer the combined space savings and energy savings that are so often a pre-requisite in building service projects today.
A shocking discovery
One less well-known side effect of the increase in pressure-boosted systems has been experienced in certain systems when the power supply had been interrupted.
This phenomenon is being increasingly noted after a ‘power down’ situation, (due to either turning the set off or a power cut), when system water has continued to be drawn off and this has resulted in a vacuum occurring within the main riser.
Once the power is restored the set will try and replace the water that has been lost in the system as quickly as possible. This sudden increase in flow will rapidly pressurise the partial vacuum in the empty pipe work that will then stop the liquid flow suddenly, just like a fast acting valve. A resultant surge will then pass through the liquid until it finds something to absorb the force, like a weak joint, which will result in flooding.
This situation can be avoided by fitting a specialist valve on the top of each riser that will eliminate any hydraulic shock such as the Grundfos AnTi-Shock Valve. These valves that operate as air and surge anticipation valves also dampen the effect of water hammer at pump start-up and allow for the controlled release of air from the system at start-up or after maintenance.
They operate by allowing the valve to take in air through the unobstructed large orifice, so when the pumps restart the resistance offered by this air cushion acts to dampen the surge. This enables the pumps to slowly and safely re-fill the system in a controlled manor.
This particular AnTi-Shock valve with its inbuilt ‘T’ outlet (to enable flushing down to drain) is a product that has been uniquely developed in partnership with valve experts Cla-Val and Grundfos.
Keeping up the pressure
There is now a range of new generation booster products available with a myriad of special features such as the new Grundfos Hydro MPC (Multi Pump Control). These sets combine a user-friendly interface with a range of unique features and controls including an installation wizard that guides you through the settings in sequence to help attain the optimal performance from your system. This is another example of how Grundfos are continuing to lead the way at all levels of building services pump technology to deliver overall better pump solutions.
Booster systems are here to stay and need to deliver a reliable, efficient and adaptable solution to meet the demands placed upon them both for today’s needs and tomorrow’s expectations.