#912 airRef for Exhaust systems

Hiroko Masuda Fri 30 Apr

When I found airRef in Haystack 4, I was happy because it sounded like I could use it for the central exhaust systems. ahuRef was only for the supply side, and I couldn't use it for the exhaust side. But when I saw the following example, EF-2 referenced AHU-3, and I realized airRef wasn't designed for the central exhaust application. It is almost like upstream to downstream referencing.

id @a-023b "Alpha Airside EF-2" airRef @a-0020 "Alpha Airside AHU-3"

In a laboratory ventilation setting, both supply and exhaust are controlled for each zone. The central exhaust system is like a mirror of the central supply system. The way I want to use airRef is:

RM001 Supply zone equip (airRef "AHU-1")

RM001 Exhaust zone equip (airRef "EF-1")

What would be Haystack's tagging recommendation for central exhaust systems? We are currently using a custom ref exhaustRef. Can airRef be used in the way I described?

Brian Frank Mon 3 May

The airRef tag isn't specific to any system - its just a generic way to model the flow of air. It is always placed on the receiving/input/consuming side and references back the output/supply side. So in your case the exhaust receives air from the the zone, so it would have an airRef that references the zone.

Hiroko Masuda Tue 4 May

Thanks for the clarification. Since airRef references back the supply side, to achieve our analytics goal, we need to keep using a proprietary reference tag on exhaust systems. One exhaust system could move air from multiple supply systems. Or multiple supply air systems could supply air to that zones that are served by a single exhaust system. If we want to check all the zone exhaust damper positions and compare them to the exhaust plenum static pressure, we need to consider the exhaust fan manifold as a parent and the zone exhaust dampers as its children. I understand the philosophy of airRef --- to describe the air path. But we need to take into account the fact that the supply system is driven by the supply fan, and the exhaust system (laboratory exhaust) is driven by the exhaust fan.

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