Timer mode on 791vx, changing how long?

With our first REALLY cold morning here (5 degrees) I've decided I might want to try the Timer mode on my 791vx to start my car every few hours.   I did it this morning and it ran for about 24 minutes.   I think that's one of the values for the remote start timeout, so I assume they use the same #s.   I couldn't find the install manual (not even on Directed's site), just the owners manual.  Is this timer a user changable value or does it require a bitwriter?

Do installers usually charge for a quick bitwriter programming?

Thanks

if they installed it no probably not... if you do, quite probably...    and yes you are right, the timer mode runs the unit for it's programmed run time...... which is why i dont recommend having a long run time if you forsee using the timer mode feature....