Chimney ventilation

Hello all, I have read many posts on ppl venting out their chimney with no concerns but how do you know if you can? Im in a basement and the bottom of my chimney is right in my flower room. It has a small access door on it. But I have a gas furnace and gas water heater that vent into this as well. On the top of the chimney there is a cap with a single stack on it. Can I just vent into this hole at the bottom or do I have to tie into whatever duct work is inside?

I did this, it was tricky though! You can but what you must remember is that you now pressurize the chimney by adding your ventilation. What happened to me was my water heater gas was coming back out of the top, you can check the opening with a lighter to see if air is being sucked in or blowing out, (its supposed to be sucking in) I dont know what your connection looks like, but if the connection just opens to the chimney flue it will pressurize the chimney too much and force air out all the easy places first which is probably not the top of the chimney. I had to stick a 90degree swivel elbow and run it into the chimney so the air is aimed up the chimney giving it direction and sending flying up the chimney instead of just dumping out and pressurizing the chimney to be forced out the top. Always check for back flow from your furnace or water heater, you may have to get a back flow prevention flange because YOU COULD DIE, a CO monitor would help save your tushie though, hope this helps.

*when i said check the top, I mean on your water heater there should be a lil wide cone shaped flange connected to a vent which then is cemented to your chimney.

Not fond of the whole dying thing so maybe I look into other possibilities

lol, buy a Carbon Monoxide monitor,