Bug: All-Air HVAC Economizer-Type Assignment to Multiple Zones

HI all,

I think I have notices a small bug when using the All-Air HVAC system? I wonder if there is a simple fix for this, or if there is a different way this component should be used to avoid the problem?

Scenario:
A simple multi-zone model, with the All-Air HVAC System applied and an Economizer type assigned:

From what I can tell, in the GH Scene the Economizer Type is getting set correctly on all the zones:

So that all seems right so far. But when exported to OSM, it appears that only the ‘first’ room keeps that Economizer assignment for some reason? If I open up the model in OS:


There does seem to be a workaround; if you break out the zones (or just Graft the input), and then assign them one at a time:

then in that case, it does appear to work as expected:

I’m not sure where the Economizer is getting lost in translation there, but just wanted to log the issue here for reference. Example GH file attached for reference.

all the best,
@edpmay

examples.gh (86.4 KB)

Thanks for reporting this, @edpmay .

It looks like the openstudio standards gem made some changes on us. Given the screenshots that you showed, I think it’s likely that this bug only affects the Packaged Single Zone (PZS) HVAC templates. I think that it happened because of this recent refactor if the PZS systems in openstudio-standards:

They must have changed the PSZ systems to enforce only one air loop per Room/Zone instead of previously when they allowed you to connect multiple Room/Zones to a single loop. I guess that’s an unconventional way to use a HVAC system that has the words “Single Zone” in its name so they just did away with it.

I’ll work on fixing this shortly. In the meantime, a better workaround instead of copy/pasting the component is just to graft the _rooms input of the “All-Air HVAC” component. That will ensure that each Room gets a separate HVAC definition and that each air loop gets the economizer properties.

Hey @Chris,

Thanks for taking a look at this. Makes sense to use graft on the rooms input for now, that seems to work properly.
thanks!
@edpmay

Hey @edpmay ,

I just wanted to let you know that I merged a fix for this:

So, once you run the LB Versioner in an hour, you shouldn’t have to worry about this anymore.

Thanks again for reporting!