Condenser Water System

condenser water system

Cooling tower of a plant.

This post is going to cover an average condenser water system you may see out in your jobs as building engineers. Also, you might find it cool, if you’re not an engineer, to be able to explain to your friends what is happening when you drive by a city and see the steam evaporating from the tops. You’ll know.

You’ll be making some long car trip, someone inside will go “I’ve always wondered what that steam is coming off of the towers for the nuclear plant.” And you’ll then go “I know. It’s the condenser water system. Now buy me lunch.”

Yep, nuclear power plants use this system, buildings in downtown Manhattan, hospitals in Nebraska, pretty much all have condenser water systems. They are vital.

It’s going to go over the function of a condenser water system, have a simple drawing or two of how you’ll see it connected to a building, property, or facility. I like the drawings, they make understanding how a system works much easier.

Condenser Water

What is it?

condenser water equation

Heat transfer equation.

It might be kind of hard to put into words, the purpose of a condenser water system. We shall try yeah?

The basic purpose or function of a condenser water system is to transfer heat. Guess that wasn’t too bad. But by simply saying it transfers heat, doesn’t really help us. As we’ve seen, a lot of things in building engineering transfer heat.

A condenser water system typically travels into and out of a building to do its job. It is usually inside the building picking up whatever heat is being generated, by whatever process, usually in conjunction with the chilled water system and then pumped outside the building to give up its heat to the atmosphere.

Where You’ve Already Seen It

You might be thinking,this is sort of confusing, I have never heard of this before. Maybe not, but you’ve seen it in action probably every day.

This concept occurs inside your fridge at home. A condenser water system in a facility takes the place of air in your home and car units. These units use just air to blow across the heat source, condensing the refrigerant. The reason they can get away with this is because the heat load on them is small.

For a building trying to remove heat from maybe hundreds of office spaces or patient rooms, the heat load is huge.

Using just air wouldn’t be enough to transfer or exchange all of that heat efficiently or quickly enough. So we pump water around and contain it using the condenser water system.

For the big, huge nuclear power plants you see off in the distance, the towers you see usually churning out that evaporation cloud, they are doing this process, this energy conversion in the form of heat transfer.

Make sure you check out the easy to follow one line condenser water system drawing. For building engineers, it is mandatory that you grasp the concepts of the system.

Condenser Water System – One Line Drawing

condenser water system

My god. The spelling mistake is going to kill me. The blue line – condenser. Dammit.

How It Works

The basic operation of a condenser water system is pretty simple really. Use the directional arrows to follow my flow path.

Note that the condenser water pump, or more frequently, pumps, can be installed in either direction. This means they can suck condenser water through some device producing heat or they can push it through depending on the installation needs.

  1. Here in this case, the condenser water is falling into the suction of the condenser water pump.
  2. It then gets discharged and pumped through a chiller or refrigeration machine.
  3. On the other side of the chiller is hot refrigerant. It gets blown over the tubes of condenser water.
  4. The condenser water flows past, never making actual contact, only exchanging heat right?
  5. The pump has so much discharge head it keeps pushing it through.
  6. The condenser water makes its way to the top of a cooling tower.
  7. In one case, there are nozzles at the top of the cooling tower, like spray nozzles the condenser water must flow through.
  8. This atomizes the water partially, making it a spray. This lets it get rid of more heat. Instead of being a streaming liquid, it is droplets of water.
  9. The droplets of water cascade down the sides of the cooling towers.
  10. Meanwhile, a huge fan on the inside is sucking air past the water droplets, sucking out even more heat that it had absorbed from inside the building.
  11. The condenser water collects in the cooling tower basin, and falls back into the suction of the pump.

Condenser Water System Components


condenser water pumps

Pumps for a condenser water system.

If you’ve spent any time on this awesome site, you know there are several posts on pumps. If you haven’t, shame on you dirt bag.

We know what a pump does. Usually a condenser water pump is of the centrifugal type so that it can moderate discharge pressure based on system needs. These pumps are also typically some of the biggest in the plant, they are transferring all of the heat from inside something to outside something, perhaps 1,000,000 square foot warehouse.

Pumps in the condenser water system move water between a heat generating device or place to another location where that heat can then be given up.

Cooling Tower

This would be where the magic happens. The awesome magic of energy again. Heat transfer, can you smell it?

In our simple condenser water system drawing, the cooling tower is where it gave up the heat. Through latent heat of condensation I believe. But a cooling tower doesn’t have to be the square metal box you see on rooftops, or the silo, towers you see across a field. I think some places in New York use the Hudson River as their condenser water.

Some plants there take a suction straight from the river, pump it through their devices, and right back into the river.

Ours is more conventional, the box. Water gets sprayed in at the top, becoming atomized. We want it atomized because this increases the exposed surface area of as many water molecules as possible. More exposed surface area equals more efficient heat transfer to the air that is rushing past.

  • More air molecules can absorb the heat from the atomized water molecules falling down past. Pretty awesome yeah?
condenser water cooling tower

Exploded view of a standard cooling tower. See the fan?

In this type of cooling tower, there is often a material inside called fill. The fill causes even more surface area of the water to be exposed to the air.

Fill is like this slatted plastic stuff that the water must fall through after being sprayed onto the fill from the nozzles. The fill hangs in sheets along the sides of the tower walls.

The huge fan inside, it draws air up and past the separated and very exposed water droplets.

In most facilities and buildings today, these fans vary their speed to reduce energy consumption. Heck the condenser water pumps do too. These fans are so large and use so much electricity when running full speed that now they use digital programming to tell them what speed to run at for the best efficiency.

The digital programming monitors the heat load, does a few calculations, and then determines what the optimal speed of the fan would be. It then tells it to run at that set point.


Strainers are not included on the drawing because I didn’t feel like it. They are standard issue though on every pump suction.

It is important that you clean the condenser water pump strainers regularly. It is crucial that you clean your cooling towers as well since they are exposed to outside elements. Some stuff can make it through and it is captured in the strainers. Also some little microbiological nasties can grow on the inside as well clogging things up.

Additionally, a sand filter system never hurt either. Some condenser water systems don’t have them, others do.

With a sand filter system, just like a home pool, all of the condenser water must pass through it. The benefit is an layer of filtration, along with the strainer. Yes, having one adds another layer of maintenance, but it can save on downtime and overall maintenance costs if run properly.


There you have it, almost all of my knowledge about condenser water systems. This came from my brain courtesy of the Navy as well as the last 15 or so years of being in the building engineering trade.

Condenser water systems are everywhere from the a/c unit in your window there, to the one in your car, to the steam clouds you see rising off of city skylines in television shows. Probably the cooling towers doing their evaporating thing.

Every engineer worth their salt should understand how a condenser water system works and the purpose behind them. All of them are different and customized to serve the needs of the property, but they all operate on the same principles.

Questions, comments, gripes? Love to hear them. I’m always open to positive criticism. Until next time.

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