how to replace component with another component in revit

[Anonymous]

for example i want to replace the smoke detector with another shape of smoke detector. And the new smoke detector will be in the exactly location that i have put with old one. 

[L.Maas]

Select the smoke detector, then from the properties browser select a different one.

There are some limitations to this:

-The families have to be of the same category

-They need to have the same hosting (e.g you can not replace a ceiling based family with a floor based family)

-You have to be aware of the origin points of both families if they align properly (otherwise correction is needed)

[barthbradley]

Are you referring the Model Geometry or the Plan View Symbol? The Symbol is likely a Generic Annotation that is Nested into the Family containing the Geometry.  If that's what you are taking about, just swap out the GA for another -- or edit and reload the existing GA.