Fermenter temperature rise time?

[whoaru99]

Have 5 gal of brew in a 7 gal Fermonster. Fermentation has slowed considerably (normally, not suggesting a problem) so I think heat from exothermic activity is minimal.

The fermenter temp is 50F right now. If I move the fermenter to a 65F space, how long will it take for the fermenter contents to rise from 50F to 65F?

 

[Broken Crow]

My Fermonsters have only ever been in a 64°-68° area, but for a 5G volume; I frequently fill cornys at 40°-50° and they take between 4-6 hours to completely equalize with room temp. (possibly less, but I haven't been overly concerned with the timing so that's just my best recollection)