Water vs air: condensers compared

Water cooled evaporative condensers are often applied in larger industrial installations

Air cooled condensers can be more cost-effective in their standard smaller configurations

Ed Whinyates of Stonegrove Refrigeration looks at some of the things to consider when it comes to choosing a condenser.

A refrigeration system needs a condenser in some form or another. Traditionally, the application of an air cooled condenser was preferred for small to medium installations, with evaporative condensers the preferred choice for medium to large installations. However, as technology has developed, this is now not always the case. 

Evaporative condensers and air cooled condensers have their own distinct advantages and disadvantages so, when selecting the best option for a refrigeration project, a number of factors need to be considered. These include (but are not limited to) size of project, available space, cost, energy efficiency and on-going maintenance.  

It is not possible to offer a definitive answer to which option is best, as there are many different aspects to consider in terms of performance and choice.

The application of water cooled systems has been used for many years and is notably prevalent on larger industrial installations. There are a number of advantages to selecting a water cooled condenser. 

It has been argued that they have better energy efficiency compared to air cooled condensers. This is due to the more efficient transfer of heat, leading to savings on energy costs and consumption. In addition to this, there are fewer exposed parts with evaporative condensers which makes them less vulnerable – making the case for their longer lifespan and the less frequent need for replacement. Evaporative condensers are also praised for their operational performance in higher temperature environments.  

When installing refrigeration equipment, the footprint of the pad, plant room or enclosure will impose on a client’s available space. Evaporative condensers don’t have the need for plenty of fresh air to operate correctly and can be sited (within reason) anywhere. From an external environment perspective there is the advantage of having a quieter operation. Evaporative condensers don’t have the ducts and vents of an air cooled condenser so there is not the same concern over noise pollution.     

Nonetheless there are some potential disadvantages to Evaporative condensers. One of these is cost. It is argued that because of the greater number of mechanical parts needed, such as cooling towers and pumps, it is a more expensive installation option.  There is also the requirement for more intense on-going maintenance and regular water treatment which add to the continued costs.  There is also the high cost and quality of water along with the requirement for a water supply.  However the case can be made that the longer lifespan and energy savings, associated with water cooled condensers, make them cost effective longer term.  Another disadvantage is the high water usage which, unfortunately, cannot be avoided.

There are a number of specific advantages to the use of air cooled condensers. Typically air cooled condensers are a more cost-effective option to install and maintain compared to water cooled condensers in their standard smaller configurations.  When looking at smaller installations, the choice of an air cooled condenser tends to be favoured offering a wider application for their use. They also provide more options for refrigeration systems at the design phase of a project. A good example of this is the increased use of packaged chillers on many industrial refrigeration applications. The knock-on effect for this kind of system is the benefit to both installation programme reduction and commissioning time on site.

Air cooled condensers don’t rely on a water to cool and so are not restricted by water availability. Also, due to the need for fewer parts, the risk of breakdown is reduced which means less on-going maintenance costs. This in turn leads to less downtime and greater reliability of the plant. Maintenance plays an extremely important part of any refrigeration system so this cannot be overlooked when making an important capital decision.  

Environmental impact has become far more relevant with refrigeration systems, with the ever-changing face of HFCs and the move towards a greater use of natural refrigerants. Air cooled condensers also play a positive role in this as there is no requirement for water, so no water wastage or the need for chemical dosing.

Like evaporative condensers, the use of air cooled condensers has some disadvantages. The footprint required to take the condenser can be larger and, with the need for no obstruction to airflow around the entire unit, can take up valuable space.  They tend to be noisier to run so this could be a problem in built-up areas. Although it is claimed that some air cooled condensers are now offering much better energy efficiency it is still argued they tend to be less energy efficient, so cost more to run.  

It is clear that both systems have their merits so it is impossible to say that one is better than the other. Each has its advantages and both can offer the ideal solution when reviewing modes of operation, size of the refrigeration plant, available space, cost and efficiency. There is also the less scientific approach of previous experience and individual preference. The design engineers at Stonegrove Refrigeration will always view the individual elements of each project and select the best option for the client.  

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