sorry if this has already been asked/answered, not finding this specific topic anywhere...

house just built and moved in to this year. wood furnace tied into gas furnace via 8" line to gas unit's plenum. all aspecta of both systems work fine (gas furnace works, central air worked this summer, wood burner and blowers work fine, etc.). My problem is that when buring wood, the gas unit's blower wont kick on while in the "auto" setting. I am basically setting the thermostat to heat and setting the temp to 60 with the fan setting on "auto". i am then burning the wood with hopes that the gas unit's plenum will heat up to the point that the fan will turn on. ultimately, and regardless of how hot the plenum gets, the gas units fan doesnt kick on and i have to manually turn the switch to "on" as opposed to "auto". Wood burner is USSC 1557m, gas unit im not sure on but looks like Johnson Controls model TG9S*MP.

any help would be appreciated.