As per Jayco website, the thermal package includes a Insulated, Heated, & Enclosed Underbelly. So there should be some sort of insulation and ducting for the heat, as well as the corrugated plastic to enclose it all..
However, speaking from experience, sometimes these options are missed from the factory.. My trailer with the thermal packaging didn't have the heat ducts installed to the underbelly... My local dealer installed it all under warranty after the fact. My point being, you may not have got everything you paid for. Ask your dealer doing repairs to take pictures for you confirming that the underbelly is infact heated and insulated before they re-install the corrugated plastic.. If you plan on doing any winter camping, this option is needed to prevent your tanks from freezing..
TT: 2015 Jayco Jayflight 26BH Elite
TV: 2014 Ram 1500 Sport, 5.7 HEMI 3.21, Firestone 1000# air suspension. WD hitch w/800# bars
SOLD: 2012 Jayco J-series 1007