CO2 Help please and thank you!

Ok I have done hours of research on several sights trying to find out about using a furnace to produce co2 getting no clear answers. My question is simple, does your furnace running blowing hot hair into the grow room produce co2 on its own? Does anyone here do this? For me it would be alot easier to buy a programable thermastat and set up a co2 program than to buy bottled co2 but the guy at the hydro store said furnaces may be designed to remove the co2 they produce.

Thanks

https://www.rollitup.org/do-yourself/1362-home-made-co2-tutorial.html

I used this during the flowering period of my first grow. had some great results. Cheap and easy to do.