I have this transformer with no datasheet. It's 16V-0-16V and rated for 3A. I'm not going to use the center-tap terminal (the 0V terminal). I'll use the two 16V terminals to get 32V AC. Should I draw 3A ? Or 1.5A?

In other words, Is the 3A for each winding? Or Is this a total power meaning a 1.5A for each winding?

 

Should be 32VAC at 3A (or 96W).

 

In other words, Is the 3A for each winding? Or Is this a total power meaning a 1.5A for each winding?

The windings are in series, so 3A:

 

What are you going to use the transformer for?
If used for a rectifier-capacitor DC output, the current rating needs to be derated about 60%.

 

The "BLACK-YELLOW 220" Gives me the idea the primary is 220V.
The 2X16V 3A makes me think it is 32V center tapped at 3A. Probably black/red/black.
The "S. H White - 110" Is there a 6th wire probably with white?

In other words, Is the 3A for each winding? Or Is this a total power meaning a 1.5A for each winding?

You can use it as a 32V 3A transformer. OR As a 16V 3A plus 16V 3A.

The transformer rating is for a resistive load with no diodes or capacitors. (light bulb for heater load) If you are using diodes and capacitor the transformer should not be used to make 3A dc. I think about 60% to 70% of 3A is all you should get out.