install pipe in chimney with gas appliances venting?

Hi,

This is my first post but I have read MANY and appreciate everyone's knowledge and enthusiasm to share.

Here's my situation:
I recently bought a house and got a stove to install. The only time I have ever installed a stove, we went straight into the brick chimney and lined it all the way up. There was nothing in the chimney.
In my new house, if you look in the basement, you can see that the gas appliances (water heater and boiler for radiators) are vented into the chimney. The fireplace on the main floor is drywalled over and I haven't punched a hole to look into it yet...
At first my plan was to just avoid the chimney and run through the wall and up the side of the house, since there is a wall-mounted air conditioner in a strategic location (and hence already a hole through the house), but running the chimney outside seems like a pain and all-around less than ideal way to go for a number of reasons...

So now I'm back to what I was hoping would be a "don't ask, don't tell" chimney situation.
My question is, do I need to redirect the vents for the gas appliances somehow if I'm going to vent the stove through the chimney? If I put pipe going all the way up from the stove, would that obstruct the proper venting of the other appliances, or can they live harmoniously together?
I was imagining that these 3" appliance vents just tap into the chimney and the vent pipe doesn't run all the way up. Is that generally the case?

It will be a 6" flue, if that makes a difference...

Trying to figure out my best option here to keep the chimney internal.

I doubt there is more than one flue. The house was built long before gas appliances were even a consideration. I think that's why, when they installed the boiler, they just sealed off the fireplace (and the interior part of the brick chimney on the second floor) with drywall.

Does anyone know if gas appliances require the flue for venting? Could I somehow just vent those out the side of the house? It is masonry and brick in the basement, so it might not be so hard to just take those two 3" pipes out the side...

Here's the thing,
I haven't been able to look inside the chimney yet because the two gas vents are sealed with mortar in the basement, all access to chimney inside the house is sealed, and the chimney on the roof is EXTREMELY high up there... I can get a ladder on it at some point but need at least a 30' to get anywhere close...

I guess I just gotta bust into the drywall where the (presumed) fireplace is...

I'll let you know when I do.

That's a good idea. I'm planning to do the install myself but if someone comes out to give me a quote then they'll probably have to get on a ladder and check out my chimney.

Better them than me...

Oh, I would climb the ladder if need be for install, I just wanted to check if I should rule it out as an option before I go up there.
I talked to a professional stove installer today on the phone and he said I pretty much have to go out through the wall. Not my first choice but I think he's probably right.

Also, my roof is a SUPER steep pitch so you're not gonna be climbing around on it at all.
My friend and old roommate works on roofs for a solar company and he laughed when he saw it.
Chimney is right at the tippy top.

I don't mind a 30' ladder but I'm not jumping up to get on it for no reason...
I'd rather do my research!

Yes yes, I no doubt would have used a rig like that.
I think the chimney is pretty much out of the running now though.

I'm sure it'll need repointing at some point though............