I currently have one (NG)water heater in the basement venting into an unlined chimney. I am adding a second one on the second floor for the hot water needs for an upstairs apartment.
As I understand it the chimney is much to large for the single water heater to be venting there.
I was planning on lining the chimney by running down sections of galvanized pipe through the chimney from the roof, then capping off the top of the chimney arouond the new vent. In my mind I'm using the old chimney as a sort of pipe chase.
For the section with just one water heater, I'm assuming I just need 3", what size should I increase it to after I tee in the second heater vent? 4" isn't quite double the area as 3", so would 5" be the correct size?
Is galvanized ok, or do I need stainless? Class B? Besides powered vent water heaters, is there another option I should consider?
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