A/C unit with electric heat

[JES2727]

I'm wiring a rooftop A/C unit with the electric heat option included. The A/C unit is rated at 14.7 amps at 480 volt, 3 phase. Max OCPD 20 amps. The heater is 30 kw. It has two sets of terminals, L4-L5-L6 & L7-L8-L9. Each set of terminals has the same ratings : "Heater Amps : 18.1" , "Heater Ampacity : 22.5" , "Max OCPD : 25". I'm unsure of the difference between "Heater Amps" and "Heater Ampacity", but either way it looks like I need to pull a seperate 25 amp circuit for each set of terminals and a third circuit (20 amps) for the A/C unit. I'm just looking for some confirmation here that I'm looking at it right, but also, I'm wondering if I have any other options since I'm running out of breaker space. Could I pull one larger circuit (60 amps) and then fuse each component seperately at the unit? Or, could I use one circuit to feed both the A/C unit and one set of heaters, since they will not operate at the same time?
Thanks.

John

 

[LarryFine]

I'd say you have it right, yes, you can run a feeder to a sub-panel by the unit, and yes, you can use one circuit for both (maybe). Simultaneous operation must be not possible (under normal operation. Of course, any lockout can be disabled)

 

[infinity]

Here's what I get from your nameplate data:

Heater has two sets of 15 KW elements. Ampacity of each is 18.1 amps(15kw/480x1.73) Minimum Circuit Ampacity is 22.5 amps (18.1x125%) Maximum OCPD is 25 amps.

Sounds like you can choose to use AC, heat with a 15 KW output or a 30 KW output. But knowing this, I'm still thinking about your questions.