5000 MTU install on a 30amp 220v breaker

[mig]

Just purchased a TED 5000.  I went to my circuit break box and there is no more space to add any circuit breakers (box is full).
The neutral bus is also fully populated.  I do have one circuit, with a 30 amp, 220v breaker (for electric dryer) which is not being
used since we converted to a gas dryer.  Can I use this this 30 amp, 220v breaker to install the TED 5000?  

I was thinking I could remove the existing wires (10 gauge, I think?) and cap them off with a wire nuts.  Then attach the red TED
wire to one breaker screw and the black TED wire to the other breaker screw.  Then remove the dryer neutral wire from the neutral
bus and attach the white TED wire to that screw slot.

Is a 30amp 220v breaker appropriate for the TED 5000?  Any problem with the putting a TED sized wire on a breaker designed for a 10 gauge?
Would I be better off purchasing a smaller breaker and replacing the existing 30amp 220v breaker?