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

April 05 2021

Product Insight

When it comes to the efficient cooling of electrical components, heat exchangers are the name of the game. As the movement toward more energy-conscious climate control and cooling systems continues to mount in the face of global climate change, this element of climate systems has emerged as a go-to cooling solution in today’s industrial manufacturing and automation space.

However, while the choice whether to deploy a heat exchanger is no longer an option, the kind of heat exchanger that best suits your climate control needs is up for debate. Air-to-air heat exchangers and air-to-water both present unique benefits and value propositions depending on the context, application, installation specifications, and the overall architecture of your industrial or manufacturing system. 

With this in mind, let’s take a quick look at the elements of air-to-air heat exchangers and air-to-water heat exchangers to help you make the most educated decision possible based on your business potential and goals.

Air-to-air heat exchangers 

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 automotive, food and beverage, and retail and logistics. 

In addition, air-to-air exchangers can utilize existing airflow patterns through convection or forced air and do not require additional accessories or equipment. To further enhance their flexibility, air-to-air exchangers utilize the airflow within an enclosure, or they can be connected to existing ductwork/HVAC systems.

There are some limitations to air-to-air heat exchangers, primarily in terms of the climates and environmental conditions in which they can be most effectively utilized. 

For example, if the difference between indoor and outdoor temperatures is too substantial then the cooling and energy-saving capability of the exchanger can be significantly reduced. The good news though is that recent advancement in Rittal’s air-to-air exchangers have optimized this functionality in climates that reach temperatures as low as  -13°F. Some of the advancements include: 

  • Enhanced filters for more varied environmental installations 
  • Digital thermostats controls to better monitor and react climate conditions 

These factors make air-to-air heat exchangers useful in applications where plumbing for liquid cooling would be difficult to install, where existing air flow patterns and equipment layout already allow for effective cooling, or situations with moderate thermal loads. HVAC engineers can install air-to-air heat exchangers quickly, which reduces lead time, cost, and the potential for disruption across your entire value chain. 

Given all the benefits and applications of air-to-air heat exchangers, they are still less efficient when compared with air-to-water exchangers because of a couple key factors.

Air-to-water heat exchangers 

The main reason why air-to-water heat exchangers are more effective overall than their air-to-air counterpart is that air is simply not as effective at transferring heat as water. Air-to-water heat exchangers use the same principle of temperature differential to provide heating or cooling, however, they alter the internal air temperature by forcing the air across water coils. 

The increased efficiency of heat transfer with air-to-water exchangers via the introduction of water significantly reduces both energy consumption and costs in a way that air-to-air exchangers just can’t match. This sizable reduction in energy use and operational cost is best demonstrated in industrial or manufacturing contexts with large thermal loads such as IT mainframe application or an automotive manufacturing facility where steady water supply is readily available.  

But as with air-to-air exchangers, air-to-water exchangers do come with their own liabilities or instances where deployment may not be as effective. Whereas air-to-air heat exchangers are easier to integrate with existing infrastructure, air-to-water exchangers need access to water, thus requiring plumbing and a reliable water supply or recirculation system. This most often means integrating pumps, valves, and other waterlow accessories. 

This means plant engineers and system integrators must weigh a couple key factors when considering an air-to-water heat exchanger system: 

  • Elevated installation costs, which requires calculations of those costs relative to the lifespan and long-term savings the air-to-water exchanger provides
  • Increased installation and integration time

Which heat exchanger is right for you?

As with any major decision in life, context matters — the environment you’re in, the challenges and opportunities in front of you, and the goals and benchmarks you set. The same is of course true for deciding which heat exchanger is best suited to meet your business goals and industry landscape. 

The ultimate decision will balance installation and operational costs, target cooling capacity, and thermal loads. Air-to-air heat exchangers can get up and running quickly and engineers can integrate them into many different kinds of applications easily. On the other hand, air-to-water heat exchangers deliver better efficiency and can suit more energy-demanding applications, but they require plumbing and waterflow integrations, which may not always be available. 

In the end, your choice of exchanger should account for the factors outlined above along with the parameters and specifications of your plant or facility to better understand which avenue is best for you.  

Don't let climate control decisions leave you overheated. Let Rittal guide you toward the right climate solution.