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?

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,

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.

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!