Surface boundary error

[la_bets]

Hi,

I am placing supply diffusers on my Microflo model but when I try to draw the geometry I get the message "Surface boundary must be contained within a surface and must not overlap existing boundaries". The only other boundary I have on the surface if the surface temperature imported from Vista. Could this create a conflict? I don't understand what happens because if I draw for example a smaller supply diffuser it sometimes work.
Another issue I noticed is that if I try to copy/move the diffuser after placing it on a surface, it sometimes disappear or do not copy. Plus I can rotate it. (How can I draw a diffuser aligned to a wall that is not parallel to any of the main axis?)

Thank you in advance for any reply.
Bets

[liamh]

I am placing supply diffusers on my Microflo model but when I try to draw the geometry I get the message "Surface boundary must be contained within a surface and must not overlap existing boundaries".

This is because you are trying to add a boundary condition onto an internal partition.

Because of the way that the rest of the VE stores/uses external construction geometry compared with internal partions, windows etc., Microflo treats these differently.

External walls/ceiling/floors do not have a boundary condition set up in "boundary" mode (their surface temperature is set in "surface" mode). Therefore when you come to draw a boundary condition on that surface there is no conflict.

Internal partitions have a boundary condition set up in "Boundary" mode that takes up the whole of the area of the surface. As the user is not allowed to draw a bounday condition over an existing one there is an error message generated if this is attempted.

To add a boundary condition to an internal wall you have to go to "boundary" mode and:

1) delete the existing "temperature" boundary condition
2) add the new boundary condition
3) draw a number of "temperature" boundaries arround the new boundary to make the rest of the wall, for example, the correct temperature (as imported from VISTA)

Another issue I noticed is that if I try to copy/move the diffuser after placing it on a surface, it sometimes disappear or do not copy. Plus I can rotate it. (How can I draw a diffuser aligned to a wall that is not parallel to any of the main axis?)

Not sure why you can't copy or move a boundary but you can draw a diffuser on a surface that isn't aligned with the Cartesian mesh in the the same way that you draw a boundary on a surface that is aligned. But Microflo doesn't model non-aligned diffuser boundaries very well and they should be avoided at all cost by rotating the ModelIT zone if possible.

[la_bets]

Thank you Liamh for your reply.
The boundary set up makes more sense to me now.
The problem with copying and moving and moving diffusers was also due to the presence of temperature boundary on internal surfaces.
Only doubt left is about rotating diffusers or drawing them non aligned to the main axis. My room has a polygonal plan with 5 sides: three of them are aligned to the x and y axis while the other two are not aligned. I need to draw diffusers on the ceiling along the whole perimeter of the room, is it possible to do this? It seems like I can only draw diffusers aligned to the Cartesian mesh and I can't rotate them.

Thanks a lot
Bets

[liamh]

Bets,

You can't rotate a boundary on a surface in Microflo. You will have to accept the boundaries on the ceiling being aligned with the x- and y-axes. If your diffuser boundary is long and thin then you could break into a number of smaller square boundaries and "stairstep" along the non-aligned wall.

Regards,
Liam

[la_bets]

Alright seems like I have to accept that.
Is it alright to assign the boundary condition imported from Vista after drawing all other boundaries present in the room? (in particular after drawing all diffusers - if I try to do it the surface temperature boundaries are drawn automatically around the diffusers but I'd like to be sure that will not cause other problems).

Thank you!
Bets

[liamh]

Yes it is fine to do it that way round.

Liam