I have a couple transformers with primaries made for 220V or 440V AC outlets (they were in industrial size uninterruptible power supplies). Would it be possible to use these transformers on 110V outlets? Obviously the output voltages would be halved, but is there any reason it wouldnt work properly otherwise?
You can always use a transformer at lower than its rated voltage. Operating at a lower voltage will reduce the idle current and idle power loss. Just don't exceed their current ratings, i.e. the current based upon the VA rating at its rated voltage.