It depends on how you are going to use the oil. If it is to be vaporized for head effect, I would drop the temperature of the water to just hot tap water, at 140F or less.
When the butane appears to be gone visually, if you can pull a vacuum to -29.9Hg, I've found that 115F works well for keeping the oil liquid enough to allow the purge gases to escape, but retain maximum carboxylic acid.
If you are going to decarboxylate it for oral consumption, I would use a deeper container and hot tap water until it looks like the butane is gone, and then set in a 250F hot oil bath to finish purging and decarboxylating.