Re; tubing, I have a pretty strong feeling that this is a convection oven and the tubing is there to direct air.
Whirlpool AGS646 Smartcook pizza oven is a convection oven with three levels, electronic controls for temperatures up to 450C and two fan motors for uniform cooking. The double cylinder system transforms the oven into a superoven that makes fresh pizza in less than 90 seconds with the appearance and taste normally only achieved by a wood fired oven.
3 level convection oven
Electronic temperature control
2 fan motors (1 top & 1 bottom)
Internal dimensions 440w x 475d x 342h
External dimensions 600w x 548d x 581h
Electrical rating 3.7kW