THERM -- Knowledge Base THERM 2.1a

THERM 2.1a: Knowledge Base

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Last update:08/14/03 03:09 PM

THERM 2.1 cannot read THERM 2.1a files
THERM 2.1a can read THERM 2.1 (version 2.1.14) files, but once saved as a 2.1a file, 2.1 will not be able to read the file. So for testing, it is VERY IMPORTANT to keep the THERM 2.1a Beta files in the THERM 2.1a program directory to avoid confusion. We do not plan to make a "Save as THERM 2.1 file" from the 2.1a version.

Results
A few simulators found a problem with the the program when running calculations on complex cross-sections (which resulted in small mesh elements and high heat fluxes) being carried out in single precision. The THERM code has been converted to double precision and a check has been added which is intended to catch any unforseen similar issues in the future. Going to double precision has a minimal affect on some answers (on the order of 0.1%) - this is less of an effect than starting at mesh parameter of 6 vs starting at mesh parameter of 8 (with all results getting to an EEN of less than 10%.)

Can't find a point that lies inside of a polygon
This message may appear when modeling a glazing system of a height greater than 4.5 inches when a suspended film is modeled in a double glazed system, such as Heat Mirror (TM). The work around is to import 2 glazing systems, stacked on top of each other. Import the first glazing system at 2.5 inches, and the second at a height to create a total desired height, such as 3.5 inches for a total of a 6 inch high glazing system. This problem will be fixed in THERM 5.0.

Glazing Systems -- Do NOT Copy and Paste Glazing Systems
When adding WINDOW 4.1 glazing systems to a THERM file, DO NOT cut or copy and then paste the glazing systems, either within the same file or between files. ALWAYS insert the glazing systems from the WINDOW 4.1 library. Copying and pasting glazing systems can cause a number of problems, including:

Multiple glazing options will get incorrect Edge U-value results

One way to insert a glazing system when the program reports that the glazing system is overlapping with existing materials, is to go to Options, Preferences, Drawing Options and de-select 'Always check of overlapping polygons'. This will let you import the glazing system even when it overlaps, so you need to make sure afterwards that you correct the geometry around the glazing system. This method should be used instead of the method described in section 6.4.1 of the Simulators Manual.

Selecting more then one glazing system
Files that have 2 glazing systems in them, such as meeting rails require some special care when selecting the glazing system by clicking on them. When you select one glazing system, and then select the 2nd glazing system, the first glazing system does not become "deselected". So you may think that you have selected the 2nd glazing system, but really what the program is displaying are the attributes of the originally selected glazing system. So it's important to "deselect" one glazing system (by clicking outside the glazing systems) before selecting another glazing system

Modeling Heat Mirror and other thin elements:
When generating the boundary conditions in a model with a very thin suspended film in an IG unit, such as Heat MirrorTM, do not have THERM "Automatically adjust points within tolerance" when generating the boundary conditions. Instead, choose the "Mark the points, but do not adjust them" radio button. This will cause THERM to draw red circles around the points it finds outside the program tolerance of 0.1 mm, but the boundary conditions will still be generated. The display of red circles can be turned 'off' by "unchecking" the View/Bad Points menu option. This is a case where there are fine details in the model that you do not want the program to automatically delete. See the fourth paragraph on page 6-10 in the THERM 2.0 User's Manual for more details.

Tape Measure Average Temperature:
THERM 2.1 is using a finer increment to calculate the Tape Meausure Average Temperature value, in order to fix a bug with that feature in THERM 2.0. Therefore, you may get somewhat different (and we assert more accurate) temperature averages with the tape measure in THERM 2.1 than in THERM 2.0.

Report Does Not Display:
If the THERM report (accessed from the File/Report menu) does not display, you may have an older version of the file richtx32.ocx which THERM 2.1 needs to display the report.

You can download the latest version of this file: richtx32.ocx

and save or copy it into your system directory. The standard system directories for the various versions of MS Windows are listed below:

For MS Windows 95/98:

copy file into c:\windows\system (overwriting the current one)

For NT/2000:

copy file into c:\winnt\system32

This is fixed in the final installation version of THERM 2.1, which has the new version of the richtx32.ocx file in the installation. We are leaving the ocx file in the FAQ for anyone who may have a previous version that still has this problem.

Arc to Polygon Conversion Does Not Work:
In some cases it may appear that when importing a DXF file into THERM, the arc to polygon feature is not working properly because the drawing comes in with a large number of points to form the arc. This may happen because the original drawing was not drawn as an "arc" but rather a series of points and connected lines. THERM will simply interpret this as points and lines, and not as an arc, and therefore, no simplification of the arc will occur using the Arc to Polygon Conversion feature in THERM.

The solution is to create the original drawing using arcs rather than points before importing it as a DXF file into THERM.