I have a Siemens 60 amp sub panel in my garage. The serial number is G1212ML1125CU. I am remodeling my garage and want to add more circuits than the remaining slots can accommodate. Currently, the feed wires go into a 60 amp breaker taking up two of the 12 slots. Is there a main breaker I could attach to the top of the busbars that the feed wires could enter instead that would open up the two slots the 60 amp breaker currently takes up? If not, are there other 60 amp panels with more slots or tandem breaker slots available? Other thoughts on how to expand? Thanks in advance [ATTACH]67963[/ATTACH]

Okay, so this is going to be a little convoluted. But if it made sense to me, I wouldn't be asking I guess, right? Anyway, the house has dual zone HVAC: upstairs and downstairs. Downstairs is oil burner, forced warm air, with central A/C. Upstairs is heat pump, with an outside compressor and inside air handler. For ease of understanding, I'll break this into A/C and H/P. In the breaker panel, there is a circuit for the downstairs A/C compressor. It is two, 20A breakers, ganged together (20A, 240V). There a circuit labeled furnace, which is one, 20A breaker (20A, 120V), which seems to control the blower and burner. Outside, next to the A/C compressor, is a disconnect box with a pull-down lever (on/off). The rating plate inside says it's a 60A disconnect. The A/C compressor outside has a data plate that states "minimum ampacity 13.7" and "max circuit breaker 20." So, the data plate and the inside circuit breakers seem to match. 20A, 240V breakers installed, with a max 20A breaker required. Good, yes? But what about that 60A disconnect? Does it matter? Or, because it's just a service disconnect and not overcurrent protection, is it okay as long as it's MINIMUM 20A? Also, the disconnect box, if you lift the cover up, exposes all the wiring. This is probably something that, to keep little prying fingers out, should have a lock installed on the cover, yes? Okay, great, now onto the heat pump: In the breaker panel, there are two circuits labeled heat pump. The first heat pump circuit is two, 50A breakers ganged together (50A, 240V). The second circuit is two 60A breakers ganged together (60A, 240V). I'm not sure which controls the air handler and which controls the compressor. Since they generally work in tandem, is there a good way to pinpoint which is which? Turn one off and try to run the blower in fan-only mode? And, like the A/C, the H/P compressor outside has a data plate that states "minimum ampacity 13.8" and "max circuit breaker 20." This causes me concern because either way, the circuit breakers are either 50A or 60A. Am I right to be concerned? Thank you all in advance.