electricity questions?

I see the heater is single phase 120-volts.
Another option is to set a receptacle fed from the same circuit as the heater.

Since the breaker is 30-amps use #10 wire to the 20-amp receptacle.

Remember the circuit breaker is there to protect the wire not the load.

During warmer months you won't have a problem...may have one in winter when the heater runs.

Good luck.

Mop