Difficulty with Cooling Tower

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Good Afternoon all,

I am trying to model a cooling tower but have not been able to make it work. I am running the model in 3.63b. The model will run if I attach the condenser loop directly to one of my chillers, but when I attach the water economizer to the condenser loop, as instructed in the documentation, I get an error message that their is no load on the condenser loop.

Has anyone had any success getting this type of system to work? The documentation is light on this topic. Any and all assistance would be greatly appreciated.

Kimberly Killian

Kimberly Killian's picture
Joined: 2011-09-30
Reputation: 0

Hi Kimberly,

You need to have at least one water cooled chiller attached to the condenser water loop in addition to the water-side economizer to get rid of that error message. Add a dummy water-cooled chiller and schedule it off at all times (use Equipment Control and have the air-cooled chillers meet the entire load - the fake water-cooled chiller will never turn on but the economizer will operate whenever possible) and verify it is not running through the hourly reports. The error should disappear and you'll get free cooling from the economizer.

Matt Dubrovich, P.E.

Matthew Dubrovich's picture
Joined: 2011-09-30
Reputation: 0

I suspect your problem might be that your screw chillers are air cooled.
If you look at the documentation (Volume 6) below, the economizer is an
all or nothing deal. If your loads aren't being satisfied by the
economizer, you will default to the air cooled system, which would zero
out your condenser loop. Where is your project located? If it is in a
humid climate, you might not actually be meeting the entire load this

Vikram Sami, LEED AP

Vikram Sami's picture
Joined: 2011-09-30
Reputation: 0