Robert Jones Posted June 9, 2009 Report Share Posted June 9, 2009 The installed gas furnace is approximately 13 yrs old. There is quite a bit of "mineralization" on the b vent and the burner compartment. Is this caused by poor drafting? The flue is shared with the water heater. Thanks Click to Enlarge 58.06 KB Click to Enlarge 65.19 KB Link to comment Share on other sites More sharing options...
John Dirks Jr Posted June 9, 2009 Report Share Posted June 9, 2009 It looks like the gasses are condensing in the flue which leaves behind the acidic corrosive minerals you see. It could be a number of things causing it. So yes, it is a drafting problem. Link to comment Share on other sites More sharing options...
hausdok Posted June 9, 2009 Report Share Posted June 9, 2009 Yep, Draft issue. That's a 90° elbow in a single-walled vent in an unheated garage. Those gases are slowing down and cooling too rapidly and condensing in that vent. What's the rule? No bend greater than 45° but one bend of 60° is allowed - isn't it? ONE TEAM - ONE FIGHT!!! Mike. Link to comment Share on other sites More sharing options...
Robert Jones Posted June 9, 2009 Author Report Share Posted June 9, 2009 Thanks guys. Mike, that is correct, per IRC 2426.6.4, bends 45 degree max. except one of 60 degree. Thanks again. Link to comment Share on other sites More sharing options...
Chad Fabry Posted June 9, 2009 Report Share Posted June 9, 2009 It looks like the gasses are condensing in the flue which leaves behind the acidic corrosive minerals you see. It could be a number of things causing it Is the residue acidic or did acidic condensate degrade a component of the flue material? Link to comment Share on other sites More sharing options...
Kyle Kubs Posted June 9, 2009 Report Share Posted June 9, 2009 Robert, just to enforce proper nomenclature. That is not a "B" vent. A B vent is a listed, double walled pipe. You probably already knew that, but if I don't post more, I'm going to be a two star member forever....[:-dunce] Link to comment Share on other sites More sharing options...
Robert Jones Posted June 9, 2009 Author Report Share Posted June 9, 2009 Sometimes I don't think before I type on this board and I really should. Nothing get's by anyone;) Link to comment Share on other sites More sharing options...
John Dirks Jr Posted June 9, 2009 Report Share Posted June 9, 2009 It looks like the gasses are condensing in the flue which leaves behind the acidic corrosive minerals you see. It could be a number of things causing it Is the residue acidic or did acidic condensate degrade a component of the flue material? Acidic condensate caused degradation. Correct? Link to comment Share on other sites More sharing options...
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