Move double pole breaker?

I have a 100 amp panel with 16 spaces allowing for 24 total circuits, so things are tight and only the bottom half allows tandem breakers. Looking to maximize space. We had central air installed a few summers ago and picture attached shows the 25a double pole breaker that the A/C guys put in. The top 20a double pole breaker runs to a (now unused) outlet that had previously powered a giant window A/C unit.

I'd like to move the 25a double pole breaker up to where the 20a double pole breaker is, get rid of the 20a double pole breaker, and use the space vacated on the lower end for tandem breakers.

Is there any reason that it would be unwise to do that? Or are there factors I need to consider that I may have overlooked? I'm familiar with basic wiring, connections and installing breakers but want to make sure I'm not overlooking properties of circuit breakers, or a reason why that 25a double pole breaker is where it is.

Either way I plan to remove the 20a double pole breaker as it is sitting unused and taking up valuable space as I upgrade wiring in other parts of the house (some K&T and aluminum to be replaced).

 

Your plan to swap the breakers around is OK. You already know about the allowed locations for tandems in your panel. Really the only other consideration for breaker placement is max stab amperage, but that is only a concern for large amperage breakers. You can't have two huge breakers right across from each other because the bus stabs have a max rating, but usually it's around 100A so not really a concern in your case.

 

That's not even a proper main panel. That 100A breaker should have hold down hardware on it.

 

Thanks for both replies - I will install the hold down equipment as well. Playing catch-up on the wiring in this house, found knob and tube tied into Romex via brittle electrical tape outside of a box in numerous locations.

 

Appears to be a Siemens panel. I see a non-Siemens 1-pole breaker that needs to be replaced at the 4th space from the bottom on the right.