Chiller AND Central CHW Plant

5 posts / 0 new
Last post

I have a building that uses an on-site chiller during the summer months, but uses chilled water from a central plant for small dehumidification loads during the winter and shoulder seasons. Both sources of CHW serve the same coils in AHUs. Does anyone know how to model this????

My issue is that I cannot apply operating schedules to chillers or to CHW meters!

Responses are much appreciated!!

Jason Curtis, Mechanical Engineer 

Jason L. Curtis's picture
Offline
Joined: 2012-02-17
Reputation: 0

Thank you for the advice. That is a good idea. Does anyone know how to add a second cooling coil in an AHU in eQuest? I was not aware that there was a way to do that.

Thanks again!

Jason Curtis

Jason L. Curtis's picture
Offline
Joined: 2012-02-17
Reputation: 0

Couldn't you just specify a second chiller to represent the central plant,
and then schedule it according to the season? You can schedule the chillers
using load management.

Michael Wilson, P.Eng.

Michael Wilson's picture
Offline
Joined: 2012-01-14
Reputation: 0

Yes, that is almost exactly what I ended up doing, just with a chilled water meter instead of a 2nd chiller. With a little help from a fellow eQuest-er in the office, I was able to get it all set up using the load management/equipment control features.

Thank you all for your input!

Jason Curtis

Jason L. Curtis's picture
Offline
Joined: 2012-02-17
Reputation: 0

Using /equipment controls/ you can specify when the chiller and when the
chilled water meter satisfy the load under different load conditions.
However, as you are looking for seasonal control, you will need to set
up a /load management/ for the chilled water loop. Load management lets
you specify which equipment control strategy is in control based on a
schedule, loop load, zone temp or OAT. So you will have 2 equipment
controls - 1 where the chilled water meter serves the loop and 1 where
the building chiller serves (you also can have a combination). You will
also have a load management which points to the chilled water meter
equip control in the summer (based on a schedule or OAT) and to the
chiller equip control in the winter.

I do not believe you can have multiple chilled water coils in eQUEST AHUs.

Brian

bfountain's picture
Offline
Joined: 2011-09-30
Reputation: 201