Danger, Will Robinson!
Ken, I would recommend you post here your final wiring topology including the
individual lengths of the two segments of nichrome before using the system
in the field and we can double-check it for you.
The math is
very important from a safety view point. For example, there is
concern you could exceed the rating of the power supply, the very worse case
scenario in the type of environment you are operating being lethal, so please
run it by us first.
We'd hate to see you suddenly stop posting.
You absolutely must also run an inline fuse. We can advise on final value once
you advise on lengths and power supply.
Best Regards
Gary Kopff B.E. (Elec. Eng.)