I bought new D'Addario 12 gauge Strings got my Fender CD 100 Acoustic Guitar. The E,A,D Strings seem to be buzzing a lot. Is that normal for new strings?
It is not normal for new strings. If your old strings didn't buzz, then your new strings may have lighter gauge and therefore the guitar fretboard is too flat. You may need to adjust the truss rod, replace the bridge saddle or get a new heavier gauge set of strings.
By the way - do not wait for the strings to get rusty in order to change them. If at all possible, replace the strings at least once a year or even better once in every 6 months. Strings lose their quality very fast due to stretching, fat/sweat from your fingers and dust. You simply will not get the most from your guitar with old strings.
Assuming that it has been tuned correctly, it is not normal. The old strings were probably 11s or maybe 12s, so there should be no problems if there weren't previously.Do they buzz open, on specific frets, maybe there is another problem with the guitar that has manifested itself when the strings were changed. Were they changed for a particular reason ? Like did one break, were they old, did you not like the sound/feel of the originals? More info. please. How old is the guitar, is it still under warranty ?