Psychrometric Error

[jrobrador19]

Hi everyone!

Has anyone else experienced this psychrometric problem? I used the default properties of a the Restroom space and when I run the Heating and Cooling loads analysis, it cannot be computed and it gets this error. 

I have tried the instructions said in the message but changing the values won't fix it.

Thank you in advance for the help!

[jrobrador19]

Hi guys,

I did a lot of iterations, and I found out what's giving me this error. It seems that if I remove the Plenum Spaces above the Restroom spaces, the analysis runs fine. You can refer to the images below.

As you can see, previously, I get a psychrometric error. But now it's okay.

Any advise on how to deal with this?

Thanks in advance!

[jrobrador19 · Accepted solution]

Hi Guys,

I have managed to solve this at last. I'm not sure if this is a bug or if it does affect the analysis.

From my previous reply, I found out that the Plenums above the Restroom spaces have been the cause of me getting the psychrometric error trough 20+ iterations of the analysis, so I tried to manipulate it's properties. 

And I found out that the Upper Limit Space parameter is causing the error. Somehow if I set the Upper Limit to a level Roof in my model, the space below encounters a psychrometric error. But if I set it to the same level, and just add a Limit Offset (what I actually did here is just pull up the space limits in the section view), the analysis comes through with results and no error.

For the people using the heating and cooling loads analysis engine in Revit, do you think this is a bug or did is it really a factor in the computation? I checked and both having the Upper Limit set to Roof and setting the limit offset from the same level renders the same Volume of the space. So in my opinion there is a bug here.

What do you think?

[lfaussK8Q8Y]

@jrobrador19 

Have you encountered this problem any more since your original post? Have you developed other solutions? I am having this same issue (the Revit heating and cooling load report giving me the odd psychrometric warning/error for plenums) and have yet to find the appropriate solutions (deleting the plenum space that is associated with the zone that is giving me this warning/error is the only way I can work around this as of now and that of course is not the appropriate solution for an accurate load report). I have other plenums in my model that are working fine and they all have the same Upper limit and limit offset values as the plenums that are not working right so I am very confused...…. I worked through your solution of manually adjusting the parameters but it has not solved the problem in my case...… Again, leaving me confused...… 

Any thoughts or recommendation would be much appreciated! 

Thanks,

Luke 

[jrobrador19]

Hi there.

I haven't encountered this issue again. But in my opinion there is a bug or a glitch here.  In my case, it was definitely the plenum above that is causing the psychrometric error, that's why I deleted them first, run the analysis which worked which prompted me to tweak on the properties of the plenum spaces.

I used the release version of Revit 2021 here. I'm not sure if the update patch (2021.1.1) had addressed this. You can try to update your software to the latest patch and do the analysis again.

[lfaussK8Q8Y]

@jrobrador19 

Thank you,

I am working in Revit 2019 and will see if the current update for that year will fix this. It is most certainly one of the strangest problems I have encountered so far with plenum spaces. 

Thanks for the response,

Luke 

[ahamed.mebd]

Hi, everyone. To remove this error, just remove any gap between the plenum and room space (see in the cross-section view) then no psychrometric error will come.

Thanks.

Rakib

[iainsavage]

Plenum level should be aligned to the bottom of the ceiling.

https://help.autodesk.com/view/RVT/2022/ENU/?guid=GUID-772FA58A-BE6F-490D-8991-95AD3A9FB42C

[d.delaqua]

I have the same problem, but when I insert the level below the ceiling, when I create the space it is generated "inside" the ceiling...
I have already made several modifications and have not found a solution.

[HVAC-Novice]

FWIW, it generally is recommended to use Levels only for actual levels (i..e an actual floor of a building). 

In your example, a level could have different ceiling heights and then you add multiple plenum levels. And when you change the ceiling height in one room, you need to manually add or change levels. 

There isn't a right or wrong.... but think of all the clutter of levels....