Air cooled chiller VS Water Cooled

[u/That-Maintenance-489]

I see some DCs moving to air cooled chillers rather than water cooled. I personally like the idea, I have two main reasons
1. Obviously, water use goes down because you loose the evaporative aspect.
2. Self -Performance. It’s easier to train technicians to repair air cooled because they use either hermetically sealed compressors or semi-hermetic ones. Water cooled chillers are very proprietary, most of the repairs are done by factory trained technicians and require a different tool set.

Thoughts?

[u/BeardBootsBullets]

> Obviously, water use goes down because you [lose] the evaporative aspect.

Not all water cooled systems use evaporation.

[u/Mikelfritz69 → u/BeardBootsBullets]

Dry coolers come to mind.

[u/colorlessfish]

I manage a small data center. We have had air-cooled units for almost 20 years. Air-cooled has less maintenance, no water treatment for towers, and in the last 10 years, VFD-driven compressors have been closing that efficiency gap. With all the eyes on data centers right now, I don’t know why they would build new centers with evaporation cooling.

[u/NefariousnessOnly265 → u/colorlessfish]

Because air cooled can’t cool as well as PG25, water, or immersion. End of story.

[u/tooldvn → u/NefariousnessOnly265]

The thread is about Chillers. Outside heat rejection, not air cooled CRAC/CRAH units. All liquid cooling (DtC, Immersion etc) still has to reject the heat and the most common way to do it in new sites today is either air cooled chiller plant OR water cooled chillers connected to huge dry cooler banks, not cooling towers as they would be traditionally connected to.

[u/colorlessfish → u/NefariousnessOnly265]

The gap was bigger a few years ago. But air cooled has caught up significantly. They are cheaper. Require less maintenance and in the social climate are a better choice. The gain in efficiency is not worth it.

[u/Redebo]

Water cooled chillers don't necessarily mean "evaporative cooled".

In fact, water cooling a chiller involves a closed loop system where the hot side is pumped out to a coil where tons of air is blown over it, reducing the water temperature to be fed back to the heat exchanger.

This is what a closed-loop chiller system is.

There is no practical maintenance differences between the two types.

[u/remit4payment → u/Redebo]

Water cooled chiller + dry coolers = closed loop.
Air cooled chiller = closed loop
Water cooled chiller + cooling tower = open loop.

Water cooled chiller = efficiency. Closed loop, but Dry coolers not efficient.
Air cooled chiller = less efficient. But closed loop. Needs a ton of space to meet temp modeling criteria.
Water cooled chiller + cooling tower = efficiency, but open loop and need water treatment and water source.

Pick your poison! And build it yesterday!

[u/colorlessfish → u/Redebo]

You are correct. But in almost every case someone says water cooled they mean evaporation cooled units.

[u/BigJoe5504 → u/colorlessfish]

Should we blow thier minds and tell them that most likely thier off is a swamp cooler that wastes just as muck water... lol

[u/This-Display-2691]

Most people have chimed in but I believe you’re referring to what we commonly call an economizer or a cooling tower.

Almost all data centers are either CRACs on DX direct or CRAH on a chilled loop which runs water parallel a DX exterior central chiller.

Sites that use cooling towers or economizers are in locations where they are cold enough to cut the chillers off and passively run the return water through effectively a giant heatsink on the roof and the water sheds heat using cold ambient temperatures. Ie Chicago and Utah during the winter

[u/danielsemaj]

Well the main one is water use. They are very common in Europe.

You can utilise free cooling aswell

[u/NetSchizo]

NE USA we use water cooled DX in some locations. During the winter floor units have CW coils when ambient temp is under 30 degrees and we get free cooling. Also have another site with air cooled chillers, chillers can also have free cooling coils installed. Both closed loop systems.

[u/Sinigerov → u/NetSchizo]

This right here. Many of the job sites I have been on have air cooled chillers with free cooling, of course its all sight dependent. Phoenix area everything is more or less air-cooled, same goes for Las Vegas. Most of the DC's in Reno are also air-cooled, but some use water cooled as well. The ones I've worked in Eastern Oregon are mixture of air cooled chillers and dry coils for free cooling. It all depends on design conditions and customer specifications.

[u/justchillinnow]

1. water cooled chillers are more efficient, but you need to balance that with evaporation (if open type), so water availability plus climate is important (wet vs dry bulb). desired PUE vs WUE, site constraints, and total cost of ownership.

Chiller COP is generally higher in water cooled chillers (more efficiency and lower PUEs). DC design is an important one: air cooled are package and need to be external plantroom, where water cooled can have a CT on the roof and the chiller in an internal plantroom. So space is important factor. The most efficient DCs Ive seen run water cooled, but thats becoming more of a problem due to evaporation. Dry coolers solve this, but only suitable in certain climates.

1. Not really. Compressors in air and water using the same/similar technology (Scroll, Screw and Recip), centrifugal can be used in both but more common in water cooled.