I have a boiler in my basement, can i tie into the exhaust safely?

I currently grow all cfls, im looking to add an hps to my flower chamber. when and if i do im thinking i can tie my exhaust into the boilers exhaust ( water heaters tied in too)
I also woder if i can tie into it, how would an inline fan work with all of this.

The exhaust goes straight up to the roof, i checked and im anxious to use it.

Please give me your thoughts.

i posted a pic and a question 2 months ago and got feed back on using my chimney to vent . my furnace and hot water tie into the same duct , i hooked my inline up to run a test and in blew my hot water pilot light out causing me to have to replace the thermalcouple. if you search my post you will find a pic i put up of my ducting . i guess if i put a small duct in line booster fan to help exhaust the HW it wouldt blow out the light but i didt wanna mess with it i live in a rental . myself my room is in basement i vent up to middle bathroom , then i vent that bathroom upstairs with 30ft of duct out a window, it works for me and get lots of fresh air threw my place

bump. Would like to hear more about this

im hoping to hear someone chime in on this subject.

You can do it the only problem is if your exhaust fan ever goes off with you will have co2 co going into your grow area.
Your fan will have to have enough pressure so that it over comes your furnace exhaust too