I am considering venting a condensing gas boiler BUDURUS GB142 into an unlined, 120 year old, brick chimney but am concerned if the acidic flue gas might damage the brick or mortar. Currently the chimney vents a 30 year old Peerless oil-fired boiler and a conventional gas DHW heater. Do I have any chance with this choice or is SS or direct vent the only options. Thank you