Banking on pumps that are energy-efficient
Such is the efficiency of pumps complying with the ErP Directive that replacement should be based on economic, not technical, considerations — as Paul Crowe of AMS Pumps explains.
January 2013 marked the first stage in a revolution in the world of pumps, but it is a revolution which has, so far, been confined to pump manufacturers and distributors. Pump end users, the very people who will stand to benefit most from the replacement of fixed-speed pumps with models that are more energy efficient, have remained largely in the dark.
The revolution has been triggered by the European Union’s ErP Directive, which has required pump manufacturers to significantly increase the overall energy efficiency of their pumps in three stages.
Stage 1, which came into force in January 2013, has limited the value of the Energy Efficiency Index (which has to appear on a pump’s name plate) to 0.27 for new glandless circulator pumps installed outside the heat generator, such as a boiler.
In August 2015 the EEI limit will be reduced to 0.23 and the product category will be widened to pumps inside the heat generator and also solar stations.
In the final implementation stage, from 2020, the directive will also apply to the replacement of integrated pumps in heat generators, and all glandless circulator pumps in the heating, air-conditioning and solar sectors.
The truth is that many pump manufacturers, like Wilo and Grundfos, are well ahead of the implementation schedule and are already manufacturing pumps to comply with stage 2, due to start in 2015. However, the focus on manufacturer compliance has inevitably confined the debate to the technicalities of the ErP Directive, in particular the process of implementation.
This focus has failed to penetrate the thinking of process engineers, construction specifiers, maintenance and plant engineers who deal with pumping issues on a daily basis and who are more concerned with benefits of the new pumps and potential cost savings.
The result is that a new high-efficiency pump is only installed when an older fixed-speed pump is beyond repair and replacement is the only option. For pump users, the benefits of a more proactive replacement of non-compliant fixed speed pumps have not, as yet, registered.
The key issue is that new pumps, which are compliant with the ErP Directive, can be up to 80% more efficient than a standard fixed-speed pump. With rising energy costs this can equate to a very significant saving on energy costs for an end user, savings which can be balanced against the cost of a new pump.
Whilst all applications are different, typical payback periods on a non-domestic system over five years old are less than two years. With older systems the timeframe can be even quicker.
For example, one application I was directly involved in, concerned a company based in the south east of England. This company used copious amounts of water during a manufacturing process. Upon inspection we found that the pump user was operating with a single pump to supply all of the factory’s water requirements.
What’s more, control of the pump was non-existent, with the water being returned back to the tank via a pressure-relief valve. In effect this meant that the pump was running uncontrolled 24 hours a day, 5 days a week for 50 weeks of the year, delivering a constant amount of water regardless of demand.
The pump user was paying nine pence per kilowatt hour which equates to a running cost of over £28 000 per year, not including maintenance and repair costs.
The solution was to install three pumps, arranged as duty, assist and standby, controlled by an inverter whilst maintaining a constant pressure. The key to delivering the energy savings was to vary the pump speed in line with demand; when there is no demand the pump stops, rather than working continually.
In terms of savings, by utilising the principle of the three pumps and by controlling the system on constant pressure, the projected energy savings were in excess of £17 000 per year.
A further example involved the use of a pump to deliver water to a cooling-water system used to cool electrical equipment during test. The existing pump delivered 1600 m3/h, but a increase in production was set to extend the flow rate to circa 2200 m3/h.
The existing pump was a long-coupled end-suction pump with a 75 kW motor controlled by a variable speed drive. By utilising new ErP compliant pumps we were able to offer him a more efficient pump delivering the increased flow rate, whilst still maintaining his current motor size.
A further benefit that pump users should take into account is standardisation of pumps around a specific manufacturer. Standardisation of pumps has additional benefits in terms of parts replacement.
My advice to pump users is to consider a full-scale audit of your site’s pumps which should involve a full pump inspection. It is only when process and maintenance engineers are equipped with the full facts, including payback periods on the capital investment, that the potential for more proactive replacement of pumps can be fully realised.
Paul Crowe is national sales manager with AMS Pumps, part of BSS Industrial.
