HVAC Question – Removing Chimney

I have a property that is going to be getting the roof replaced in the next few weeks due to the last storms that came through. The house currently has a chimney that is in rough shape and I would like to remove the chimney down below the roof line. The furnace currently vents through the chimney, and there is a 6″ metal liner in the chimney for the furnace. I have no plans to ever run a water heater through it, current water heater is electric.

I have found a connector to go from chimney liner to B-vent. My question is can I just convert the chimney liner to a B-vent right at the top of the chimney, and then run the b-vent out the roof?

Obviously I would need to follow all install reqs for the B-vent for spacing when going through the roof.

Not sure about the b vent off the chimney and then through the roof , but if you can afford it , upgrade to a high efficiency furnace , vent with pvc and totally eliminate the chimney .

I agree with Mike

I don’t see why not as long as you keep your clearances and the connector from single wall to B-vent is an approved connector.
Single wall 6″
B-Vent 1″

I would make sure you seal off around the liner With mortar so you don’t have heat loss between the chimney and liner this will cause you to have ice dams in the winter months

I would do this right blow the roof line take a 6″ storm collar invert it and place it on the top of the masonary chimney below the roof line fill with mortar and build mortar up around that to the outer edges of the masonry chimney this will prevent heat lose in your attic

I just don’t think you could get the b vent to seal into the sleeve securely. I guess you could get it close and fire caulk the heck out of it. It’s just not what I would do. Pm me if you need a bid on a new furnace.

I spoke with our local building inspector. He said the chimney should not have had a single liner to begin with. He said I should run B-vent all the way down and out of the chimney, and in doing so this will help keep vented gasses warmer. He said I would get excessive moisture with the single wall sleeve, which makes sense since ultimately that is what caused my chimney to be damaged in the first place.

I will seal the opening on the top of the chimney around the new B-vent I am installing, there is an adapter available to do that.

Much cheaper option that a new furnace and A/C unit, and this is a rental property so I don’t want to dump a bunch of money into it now.

Thanks everyone!