I don't think they make 2750W 120V heater elements. I got this number because:
The 5500W elements can only produce this much power when operating at 240V. If you cut the voltage in half, to the normal 120V your wall receptacle provides, your power drops by a quarter (to 1375W). Since you have two, your can deliver 2750W. Assuming they are on the same circuit:
A chugger pump draws about 1.3A at 120V, so if you are working with one, you will be drawing somewhere in the neighborhood of 24.2-24.5A or 25.5A if using two pumps (then the minor additions of lights, your PID controller, etc...). It would be best to run this on a 30A circuit just to be safe (no need for multiple circuits).
Check your control box and see if you have any 30A circuits outdoors (or wherever you brew). This will be shown on the breaker. If you don't have a 30A circuit, or there isn't one where you brew/are planning to brew, you'll need to have an electrician come in and wire one up for you (this can be done by yourself, and inspected by an electrician, but I don't recommend it, especially if you have no professional experience in the field). If you have to do get one put in, you might as well get him to install a 240V, 30A circuit, so that you don't have to deal with 120V at all.
I'm relatively new to all of this electrical stuff as well, so I'm not sure everything right there is 100% correct. I'll leave it to someone more qualified to confirm what I've said here.