I don't think this is an appropriate way to address a deacon.
I believe this confusion comes from the prayer for the departed, where the deacon's response, which refers to every group as "our fathers", except for deacons, where it says "our brethren the deacons", and then goes on to refer to "our fathers the laymen."
I believe that this is because this deacon's response would, shockingly, have originally been said by a deacon, not a chanter or reader. As such it makes sense for them to refer to their fellow deacons as brothers. I do not believe though that it indicates that they should always be called Brother as a title, since even laymen who have no order are called Fathers in the prayer.
I'm told that the old, authentic tradition of the whole Church is to refer to them as "Father Deacon", as the EO do today. However, I'll bet that this tradition died for us when our 'deacons' started being 6 year old boys. Since it is currently in disuse, it would be strange to address them as "Father Deacon Name", but "Brother Name" certainly isn't respectful to a member of the major orders. "Deacon Name" would be a good compromise.