Water chillers can either be a completely closed loop design or a design that utilizes a water reservoir. For the purpose of this evaluation, we will discuss the tank model chiller, which is shown above. It has the same components as the closed loop system with the addition of a reservoir. What the reservoir does for you is allows for more variance in the demand from your equipment. For example: let's say your piece of equipment varies its load from 3 to 5 tons. This could cause a "short cycling" condition for the compressor in a closed loop system because of the rapid cooling and warming of the low volume of water in the system. The reservoir acts as a buffer because of the volume of water which takes longer to cool and warm back up. This allows the compressor to stay on longer and off longer during these varied load conditions.

The closed loop design is more for constant load demands. Either system will do the job when sized correctly. So choosing the system based on demand is important in maintaining the life of your chiller.

Now that we have explained a little about two designs of our chiller, let's start the comparison.

The water tower system also uses a storage tank. This tank has an open top. With an open top comes much debris such as leaves, sticks, small animals etc. Also, the system is typically located outdoors. This leaves the water subject to even more than debris; it is also subject to the weather. In the summer, the water is constantly evaporating and in the winter it freezes unless treated with an anti-freeze. In addition to the constant evaporation in the summer, the water towers main design is based on evaporation. The water is pumped over a mesh type filament while air is blowing across the filament. This causes even more evaporation of water while dropping the water's temperature. This will not yield a large drop in temperature, but will result in a large waste of water.

The chiller system circulates water through a heat exchanger. A heat exchanger is a device with two or more circuits designed to allow heat transfer from one medium to the next. In our case, the heat exchanger has the water to be cooled in one circuit and cold refrigerant in the other circuit. As the water passes through the heat exchanger, it is cooled by the cold refrigerant and the cold refrigerant becomes warm. The warm refrigerant is sent back to the compressor where it is then compressed into a high pressure gas, run through the condenser and changed to a high pressure liquid and finally sent back to an expansion valve which allows a large pressure drop to take place in the refrigerant. This pressure drop of the refrigerant drastically cools the refrigerant. It is then injected back into the heat exchanger and the process continues. This allows you to get a temperature of water that you want. If you want 50 degree water with a water tower, you have to wait until it is 50 degrees outside because it relies on evaporation for temperature drop. Granted, there won't be much evaporation at 50 degrees, but the ambient temperature will make up that difference.

Using the chiller, you only have to set the controller to 50 degrees and let the chiller do the work. The big point is that the water circulating through the chiller and your piece of equipment, remains in the circulation process. It doesn't evaporate or collect debris or catch small animals which could lead to a quickly clogged water circuit in you equipment.

Another great aspect of our chiller system is staged capacity. Say you want to run your machine and it requires 10 tons of cooling when at full capacity and you also want to run 5 tons worth of spot cooling in the summer. With our 15 ton tank model chiller, you can do just that. Now let's say it's winter and the spot cooler is off and your machine only needs 5 tons of cooling because it is not in a high demand cycle. You still use our 15 ton tank model chiller. With our staged capacity design, we build your chiller with 3 separate circuits. This means 3 five ton compressors and 3 five ton heat exchangers. What makes this so great is now only one of the compressors is running because your load is only 5 tons. That will save 66% of the required electricity to run the 15 ton.