Chiller Efficiency: Hot to Cold 

At its most basic definition, efficiency is a ratio of output to input. While no machine is without its losses, some are better at translating input, to output, than others. First, let us examine the efficiency ratings for chillers that are used to cool spaces by absorbing the hot air of an indoor environment, and dumping it outside. 

In cooling, heat is absorbed (from the room that is to be cooled) and subsequently rejected at  higher temperature than the outdoor ambient conditions. To raise temperature, and aid the heat transfer process, some work needs to be done by the air conditioner.

This means that a chiller rated to 1000W of cooling will always need over 1000W of power input to deliver that rating. The logic behind the efficiency rating for a chiller’s efficiency is simple; a chiller that requires 1100 kW to deliver 1000 kW of cooling performance has an efficiency of approximately 91%, while a chiller that requires 1200 kW to deliver 1000 kW of cooling performance is less efficient, at approximately 83%. 

As we will learn in part 2, measuring the efficiency of heat pumps as they create temperature transfer from a hot environment to a cold environment, or vice versa  is slightly less intuitive. For now, let’s make sure we understand the two primary units that measure cold to hot temperature transfer: 

EER 

‘EER’ stands for Energy Efficiency Ratio. 

Based on cooling capability and efficiency. It is identified by dividing net cooling capacity by total electrical power input. EER is tested under specific operating conditions, with Evaporating Entering Air of 80°F DB and 67°F WB, ambient air of 95°F, and static pressure requirements that vary according to the chiller’s weight. 

EER is useful as it allows for an apples-to-apples comparison across the market thanks to its provision of standardised parameters for testing conditions. 

SEER 

As operating conditions have a significant impact on chiller efficiency, it is valuable to measure a chiller’s performance across different points, and this is what differentiates SEER from EER. 

‘SEER’ stands for Seasonal Energy Efficiency Ratio. 

Like EER, it measures chiller performance under specific temperature and humidity levels, but it is expressed as the weighted average of tests conducted under four different operating conditions. 

The Most Efficient Chiller According to SEER

Clivet’s WSAN-YSC4 proudly boasts the highest SEER on the market. 

An air-cooled heat pump, this model features multiscroll technology that perfectly matches the cooling load of your plantroom, and follows the load with highly responsive staging. With a capacity ranging from 222 kW to 675 kW, the Excellence version offers a SEER value of up to 5.0. 

It also offers low noise operation, smart defrosting and your choice of plate, or shell and tube heat exchangers. To learn if this chiller is right for your project, chat with Masterflow about your plantroom now. 

But Wait, There’s More! 

When intuitively observing the values pertaining to the efficiency of a heat pump’s function, the numbers may at first appear to not make sense, as the temperature generated and transferred by the pump is higher than the source temperature. 

Luckily, a simple mindset shift and a new set of efficiency terminologies make understanding a heat pump’s performance a non-issue. To learn about standards for measuring heat pump efficiency, jump to our article discussing COP, IPLV and NPLV.