Climate control

Balancing the Value of Air-to-Air and Air-to-Water Heat Exchangers

Guest contributor: Eric Corzine, Product Manager Climate Control, Rittal

Heat exchangers provide highly efficient cooling for electrical components. As energy costs increase, they are getting more consideration by system designers. Before making a design decision between air-to-air and air-to-water heat exchangers,  it is important to weigh installation considerations and use-cases. Here, we have provided an overview of each technology to help you determine which can best impact your equipment and your bottom line.


Air-to-air heat exchangers are the most common type of exchangers. They work by utilizing the difference between the hotter internal temperature of an enclosure and the cooler, ambient air temperature. Engineers can implement air-to-air exchangers in a variety of industrial environments, including food and beverage, waste and wastewater, and automotive.

Air-to-air exchangers can utilize existing airflow patterns, through convection or forced air, and do not require additional accessories or equipment. The technology can utilize the airflow within an enclosure or can connect to existing ductwork and HVAC systems.

There are some limitations to air-to-air heat exchangers, particularly in the climates they could be installed. For instance, if the difference between indoor and outdoor temperatures is to great then the effectiveness of the exchangers can be significantly reduced. Recent technology upgrades, however, have made air-to-air exchangers functional even in climates that reach temperatures of -13°F.

These factors make air-to-air heat exchangers useful in applications where plumbing for liquid cooling would be difficult to install, and where existing air flow patterns and equipment layout allow for effective cooling. Often, this means situations with moderate thermal loads. HVAC engineers can install them quickly as well, which reduces setup time and costs. However, they are still less efficient compared to air-to-water exchangers because air is not as effective at transferring heat as water.

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Air-to-water heat exchangers use the same principle of temperature differential to provide heating or cooling, however, they alter the temperature of air by forcing it across water coils.

Because of the efficient heat transfer capabilities of water, they can help reduce energy use and utility costs significantly. This is especially useful in situations with large thermal loads, such as IT mainframe applications or an automotive manufacturing environment where water is already available.

One of the drawbacks of air-to-water heat exchangers is the need to pipe water to the unit. The technology requires plumbing and a reliable water supply or recirculation system, which often means pumps, valves, and other accessories.

These plumbing concerns often mean higher installation costs, so engineers need to balance the initial cost with the expected savings over the lifetime of the exchanger. Overall, air-to-water exchangers are useful for high-demand, energy intensive applications.

Making the Right Choice

It is important to consider the right exchanger for your specific climate control situation. The ultimate decision will balance installation and operational costs, target cooling capacity and thermal loads.

Air-to-air exchangers can get up and running quickly and engineers can integrate them into many different kinds of applications easily. Air-to-water exchangers deliver better efficiency and can suit more energy-demanding applications, but they require plumbing and water supplies, which may not always be available. The ultimate choice, then, should consider these factors and engineers should thoroughly research both types of exchangers to understand which one will best suit their application.

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CMA/Flodyne/Hydradyne is an authorized  Rittal distributor in Illinois, Wisconsin, Iowa and Northern Indiana.

In addition to distribution, we design and fabricate complete engineered systems, including hydraulic power units, electrical control panels, pneumatic panels & aluminum framing. Our advanced components and system solutions are found in a wide variety of industrial applications such as wind energy, solar energy, process control and more.

Considerations for Industrial Enclosure Cooling

Guest contributor, Eric Corzine, Product Manager – Climate Control, Rittal

Data Centers and server racks run hot. Protecting the technology backbone of your company means managing air flow, temperature, energy consumption and cooling technology.

Rittal, the world’s largest enclosure manufacturer and a leader in thermal management of electrical, electronic and IT equipment, offers some important guidelines to ensure your equipment stays in optimum condition. The following tips are based on decades of practical experience in the use of enclosures climate control solution in industrial environments. By ensuring sufficient planning and maintenance guidelines are in place, control cabinets and electronic enclosures can be last longer and be more energy-efficient.

7 Considerations for More Efficient Enclosures

1. Devices and electrical components must be installed in the enclosure in accordance with the manufacturer instructions. Storage space for necessary documents and circuit diagrams should also be taken into account during the planning phase.

2. When arranging the components in the enclosure, verify that the cooling air flows from top to bottom. You can ensure this in the planning stages by properly routing the air flow away from the electronic components. When roof-mounted units are used, particular attention needs to be paid to the air flow from blowers built into electrical components. The use of air duct systems is advisable in the case of roof-mounted cooling units

Proper Enclosure Heat Dissipation

3. There should be sufficient space for air to flow between the parts and electrical components.

4. Air intake openings of climate control components must not be obstructed by electrical devices equipment or cable ducts. With all climate control solutions, the cold air should always be routed close to drive units. This is where the greatest heat losses occur. This arrangement ensures that the cold supply air from the climate control solution optimally cools the drive units without losses.

Air intake design for cooling enclosures

5. Internal temperatures of the enclosure should always be set to +35◦C. There is no technical justification for setting the temperature any lower. If the temperature inside the enclosure is any lower, condensation will be significantly increased.

6. Institute a systematic cleaning cycle. As most climate control components are used in industrial environments external filters of the climate control must be maintained to ensure long-lasting operation.

7. Ensure the correct filters are used for the industry application.

PU Filter for Industrial Enclosure Cooling

In heavily dust-laden atmospheres, PU filters should be used and replaced on a regular basis. Cooling units with Ri Nano coating typically do not need a dust filter.

Metal Filter for Enclosures

If the air is oil-contaminated, use metal filters. These separate the oil condensate from the air and can be cleaned with appropriate detergents

Textile Enclosure Lint Filter

In the textile industry, the use of lint filters is recommended.

Fiber Mat Filter

Chopped fibre mat filters are not suitable for cooling units.

CMAFH Rittal Resources:

Rittal Wallmount Program

Rittal Enclosure and Process Cooling handbook

Rittal Innovations 2016

The Future of Cooling Technology in Industrial Enclosures

by Eric Corzine, Product Manager, Climate Control at Rittal

As industrial processes scale, the threats and challenges of cooling the racks of automation equipment increase exponentially. Sophisticated, sensitive electronics and drives are the backbone of many industrial systems. This equipment is often placed inside enclosures to protect it from environmental influences such as temperature, moisture and contaminants like corrosive vapors and dust. If these are not prevented, electronic components will inevitably fail, eventually leading to the shut-down of entire production systems. The failure of a production system can add up to losses for an operation.

What will the future look like?
The single most important environmental factor to manage in industrial enclosures is temperature.  Relative to each individual component, the heat of electronic components has increased significantly in recent years. At the same time, the density inside control cabinets has increased dramatically, resulting in a 50 – 60% increase in heat in the enclosures.

With the advent of microelectronics and new electronic components, the requirements for professional enclosure construction and heat dissipation have evolved dramatically over the last few years. Modern enclosure climate control systems must take these challenges into account, offering the best technical solution while guaranteeing optimum energy efficiency. If heat is not managed properly and the maximum permitted operating temperature is exceeded, the service life of these components is halved and the failure rate is doubled.

Trouble-free operation and functioning of production lines is heavily dependent on how the heat generated by electrical and electronic components is dissipated from the enclosure to the ambient environment. We distinguish three different types methods of heat transfer:

  • Thermal radiation
  • Thermal conduction
  • Convection

In the case of enclosures and electronic housings, we are mainly concerned with thermal conduction and convection. With thermal radiation, heat is passed from one body to another in the form of radiation energy, without a medium material, and plays a minor role here.

Whether we are dealing with heat conduction or convection depends on whether the enclosure is open (air permeable) or closed (air-tight). With an open enclosure, the heat (heat loss) can be dissipated from the enclosure by means of air circulation, i.e. thermal conduction, from inside to outside and is typically in a controlled environment such as data centers. However, if the enclosure has to remain closed due to harsher conditions, the heat can only be dissipated via the enclosure walls, i.e. through convection. Depending on the amount of heat loss of the components, these methods may not sufficiently cool the equipment and a climate control product may be required.

Identifying the proper cooling device depends upon the differences between the ambient temperature (Tu) and the desired enclosure internal temperature (Ti).

An additional factor to consider when choosing a means to cooling is the environment in which the enclosure is installed and the ingress protection (IP) rating required.  Each climate product has corresponding IP ratings:

Other innovative, hybrid cooling technologies have been developed that rely upon two parallel cooling circuits working together depending on the temperature differential. An integral heat pipe dissipates heat from the enclosure when the ambient temperature is below the setpoint, providing passive cooling. Active climatization is achieved when the compressor’s cooling circuit is engaged and provides cooling via speed-controlled components for demand-based cooling. Combining the two circuits reduces temperature hysteresis and provides more precise cooling. Not only is energy consumption far less than with conventional technology, but the improved temperature stability leads to longer service life of both the components within the enclosure and the cooling unit itself.

The reliability of electrical and electronic components in an enclosure can be put at risk not only by excessively high temperatures, but also by excessively low ones. The enclosure interior must be heated, particularly to prevent moisture and protect against frost. It is also necessary to prevent condensation within the enclosure. The latest generation of enclosure heaters has been developed with the help of extensive Computational Fluid Dynamics (CFD) analyses. The positioning of the heater is of fundamental importance for even temperature distribution inside the enclosure. Placement of the heater in the floor area of the enclosure is recommended in order to achieve an optimum distribution of temperature and hence efficiency. Thanks to positive temperature coefficient (PTC) technology, power consumption is reduced at the maximum heater surface temperature. Together with a thermostat, this results in demand-oriented, energy-saving heating.

Smarter, intuitive, and more efficient designs will need to be a staple no matter what setting the enclosure is in.  Designers will need to take careful consideration in the initial planning stages of projects, ensuring that the appropriate cooling technology is incorporated into designs.



CMA/Flodyne/Hydradyne is an authorized  Rittal distributor in Illinois, Wisconsin, Iowa and Northern Indiana.

In addition to distribution, we design and fabricate complete engineered systems, including hydraulic power units, electrical control panels, pneumatic panels & aluminum framing. Our advanced components and system solutions are found in a wide variety of industrial applications such as wind energy, solar energy, process control and more.