The Scottish keeper who joined City from Albion Rovers and made 38 appearances for the Sky Blues, had been at Wrexham and the deal between the two clubs means that he can only play for the Conference money team from January 1st.
Speaking to Crawley Town's official website, Crawley boss Steve Evans said: ''Scott is an outstanding goalkeeper and we are delighted to add him to our squad.
''The lad wants to come to Crawley Town and fight for his place in the team, that he will get with Michel Kuipers. There were a number of good football clubs who wanted his signature but we have been rewarded for our hard work and patience.
''He is well known to Sergio Torres from when they played together at Wycombe Wanderers and of course Danny Hall from his loan spell at Shrewsbury Town, they both could not speak highly enough of him. The lad stands 6'3 tall and his kicking is exceptional. I seem to recall he was named in the PFA team of the Year for League 2 in 2009 which is a team selected by the managers in that respective league, so that is further evidence of the quality of goalkeeper we have recruited".