I think you will find it is intended to be +/- 1,500w, and the math is like this, with nominal voltages (48V, 24V respectively):
R R R_Tot I P
series 0.77 0.77 1.54 31.25 1,500
parallel 1.30 1.30 0.38 62.50 1,500
It can be hard to get an accurate resistance reading with an ohm meter, and the resistance can change after it heats up. You're better to measure the current, measure the voltage and do the math if possible. I'm doubtful that you have 5.5 ohms.
If you power only one (half) element, it will likely burn out.