michaelcherr had written this in response to
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: The General Handyman unlicensed types are the only ones I could afford right now, and I know more than most of them, so I'm going to do it myself. I'm unemployed and have plenty of time to do research and do a professional quality/safe job. I am worried about the safetey of the existing setup, which is why I'm asking questions and wanting to do it up right. (I'm also probably loosing the grandfather clause because of me adding the second)
I was planning on capping the chimney with masonry around the new vent to stop drafts. Will that be enough. Going with double wall the whole way seems overkill, but if it's needed, then I can do it. opinions?
The owner's manual shows illustrations where more than one appliance share a vent, so I know at least teh one i'm adding allows it. I will consult the other manufacture.
I am wondering how a professional HVAC person determines the correct size for a vent? I am familiar with/and can find charts and tables for every other trade it seems.
My intuition tells me that since both appliances need a 3" flue which is approx 28.27 sq in then I need a 5" flue after they join which is approx
78.53 sq in.
The rule I found was that for venting into a chimney the area can't exceed seven times the flue size feeding it. Since 78 is less than seven times greater than 28, then I should be fine?
I was thinking about going with stainless class B for the last section exposed to the elements. I've seen way too many rusty galvanized ones.
Normally I see galvanized used for inside the house, but Steve suggested aluminum or stainless. Just guessing, but I don't think I will like the price of stainless. Which would be better for inside the chimney: Aluminum or Galvanized?
Thanks for the time and advise Mike