Mark, the main thing is to be careful with the safety side of this...MOST DH units have electric as a option. So that would entail safety switches AND components for HVAC systems....NOTE I'll keep ENDORSING SAFETY!!!! The force gas heat as the salamender is a NO-NO!!!! Dangerous as a cocked gun with a hair trigger AND it just got dropped!!!
I built my kiln and went with the hydroponics theory. I use a water heater with water pump and heater core. gives me 140+ deg off coils. I wanted to go electric HVAC unit BUT I couldn't find a HVAC person that could relate to the use of or how the operation could be set up correctly.
A Gas HVAC can be used IF air is kept filter heavily as there is NO flame contact to actual air in the kiln....all flows through a chamber NOT touching the flames....DON'T use anything with open flames!!!! Again Russian roulette!!!
Bottom line is ....BE SAFE!!! FIRE is a great risk!!!!
There's several companies that have small kilns for sterilizing.....maybe you need a "firewood" sterilizer....you are just trying to finish off the bugs with heat aren't you???? hint hint.
I beat the odds once BUT I almost cost myself a lot as one source of electric heat I tried the safety switch DIDN'T work...MAJOR melt down of parts.... I couldn't find my pics of damage BUT I got to it just prior to igniting. Bottomline is ...safety switches and company testings are for a reason!!!
I hope this helps. Enjoy drying SAFELY!!!