Wall Based Family - Elevation vs. Height Parameter

[c2phace450550]

Hello,
I was having an issue when placing electrical receptacles. Basically, the automatic "elevation" constraint takes over and overrides the height my family was built at above the reference level. I have tried adding an instance parameter to adjust the families after placing with no luck - making adjustments to this parameter after placing the object has no effect. I thought maybe Revit just overrides the heights of these objects no matter what, but then I found a family that I had built for another project that works somehow! You can adjust the "placement" parameter after inserting the receptacle and it works perfectly (and somehow the "elevation" constraint stays the same).

I've tried recreating it to figure out why it works, but even with every setting (that I can think of) being the same, I can not manage to recreate it.
I know A LOT of other users have had similar issues, so I was hoping to investigate the 'working' family and report back on how it works... but I need help.

I've attached this family for you all to dissect.

If you aren't sure why I would want a family based parameter, instead of the built-in Revit "elevation" constraint, here's why: My goal is to have a checkbox for an over counter receptacle in the family. When you check this the height is adjusted to a specific preset. Can't seem to do this is the parameter is being ignored.

Thanks in advance for the help!

[barthbradley]

Change the horizontal center Reference Plane; the one that you dimensioned “Placement height” from, to “Center (Elevation)” ORIGIN.

[marmiketin]

The elevation parameter adjusts the height from the level line within the family to the horizontal reference plane which defines the origin. Both these planes are in the same place in default families. To make the height adjust using a parameter you need to add a second horizontal reference plane above the one that defines origin and associate all the elements of the family to this plane. Then add a dimension from the origin plane to the new one you created and give it a height parameter.