#839 Tagging Chilled Water System

David Waterworth Tue 14 Jul

I'm looking for guidance on how to apply tags to a typical chiller system, i.e.

2 chillers - each chiller has a series of points and then there's a points common to both i.e. there is only one chilled water entering / leaving temperature point.

Similarly the 3 cooling towers have separate fan speed / status / enable points, and common entering / leaving temperatures etc.

One of the chillers also has an HLI, and there are pumps and vsd's etc.

The Haystack documentation describes nesting a single chiller and cooling tower in a chillerPlant. It's not really clear though if the intent is to nest multiple chillers in a chillerPlant (or a chiller), multiple cooling towers in another chillerPlant (or cooling tower) and then nest these in third chillerPlant?

I've looked through the forum and there seems to be a number of posts indicating that work has/is being done to make the chiller representation more flexible but nothing that really answers my question.

Stephen Frank Wed 15 Jul

David, I'm not sure there's one right way. What we have done is use a single chilledWaterPlant as the umbrella for all equipment (chillers, VFDs, pumps, cooling towers, etc.) that make up a chilled water plant. Anything at the plant level (e.g. overall entering/leaving flows and temps) can be created on the chilledWaterPlant; otherwise we create the points on specific chiller, pump, coolingTower, etc. equips. We have also used some custom (at least in Haystack 3) tags for defining chilled water loops within the plant.

You can use equipRef on an equip to nest it inside another equip; in this case I think you would use (e.g.) equipRef -> chilledWaterPlant to nest inside your chilled water plant.

Partially this is driven by understanding your use case and what rules or logic you need to enable by the tag structure. I think that question is best answered within your team.

Jay Herron Wed 15 Jul

Hey David, I can confirm that we model plants in the same way as Stephen describes in his first paragraph.

David Waterworth Thu 16 Jul

Thanks, yes it makes sense keeping things flat where possible.

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