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PsyRhoAirFnPbTdbW: RhoAir (Density of Air) is calculated <= 0 [-8.48360E-019]

asked 2016-10-18 20:18:29 -0600

PM gravatar image

updated 2016-10-19 11:37:15 -0600

Hello, I'm having a problem with my OS model that has zone WSHP. See attached photo below. When I ran the model, I received this error message below and I don't know to fix it. * Severe * PsyRhoAirFnPbTdbW: RhoAir (Density of Air) is calculated <= 0 [-8.48360E-019]. * ~~~ * pb =[93779.00], tdb=[-2.44E+020], w=[0.3583424]. * ~~~ * Routine=Unknown, * Fatal * Program terminates due to preceding condition. ...Summary of Errors that led to program termination: ..... Reference severe error count=11 ..... Last severe error=PsyRhoAirFnPbTdbW: RhoAir (Density of Air) is calculated <= 0 [-8.48360E-019].C:\fakepath\2016-10-18 18_20_01-Proposed_Start_20161018.osm.png

Any help would be greatly appreciated. Thank you. PM

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answered 2016-10-19 11:12:46 -0600

Try looking at these threads below. It looks like your tdb is really low so it may be an error with an envelope input somewhere, such as in walkin coolers.

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Thank you. Both links were very helpful. I have multiple systems (WSHP and Ductless split HP system) control in one thermal zone (THZ). I also suspected that the staircase THZ runs from the 1st floor thru 21st floor that has no HVAC system in this zone causing the problem. I added the unit heater in this zone and it works fine now. Thanks again for the hints.

PM gravatar image PM  ( 2016-10-23 00:02:16 -0600 )edit

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Asked: 2016-10-18 20:18:29 -0600

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Last updated: Oct 19 '16