Error: Negative inside convection coefft for construction ty

[bootsam]

Error: Negative inside convection coefft for construction type FRAME

Ive imported this 6.1 project into 6.4 and i get this error if i try to run cibse loads. It ran fine in 6.1. I cannot find a construction named FRAME. I checked the glazing. Any ideas?

[PCully]

Hi,

This message usually means a Glazing Construction has been corrupted during the upgrade. I'd start by looking at the External Glazing and check things like the Frame inputs (there are new inputs here for Surface area ratios so maybe they didn't pick up a good default/initial value?).

Be careful as we've found that even Constructions in the project that aren't actually assigned to the model can trigger the error.

If you can't locate this then the last resort would be to delete unused Constructions until the affected one is removed and you can run the sim - I would hope you can catch the problem before then though. Would be nice if the error message actually told you which Construction it was...add that to the dev task list.

Phil

[bootsam]

Phil,

Thanks. I note both the inside and outside surface ratios have been assigned an initial value of 1.0. on all glazed constructions. Now i am not sure what these are and/or what they do so I assume this initial value to be correct? Is this the case?

mark

The problem lies with the outside and inside surface resistances. I usually just edit these until i get the u value i need. Guess i am going to have to look into these.

[PCully]

1 is the default for outside surface area ratio and inside surface area ratio for a new project (the default window con is low-e double glazing (6mm+6mm) (2002 regs)) so i don't think this is the problem for you.

Are there a lot of glazed constructions in the project? I think deleting some of these will be the fastest way to a solution tat lets you continue your calcs.

Phil

[bootsam]

Phil,

I just deleted them and started again. Problem solved. I printscreened my data first and just re-entered it. No problem. Thanks.

Mark

[bbrannon4]

I'm having the exact same problem in VE 2017. But in my case it complains about one construction, so I delete it and create it from scratch, and then it complains about another, so I do the same, but then it goes back to the first again! I even started a new project with the same ones, so clearly there's an issue with the constructions, but I've been pretty detailed about getting the values from Window and Therm. I think I'm not actually fixing anything but the constructions are being renumbered so the error pops out of a different one each time.