We've just had a contractor build a new wall in our basement, to enclose the hot water tank and brand new gas furnace (York).
We had to call a furnace repairman to replace the overheat switch, due to all the drywall dust that clogged up the system.
While he was fixing and cleaning the furnace, he pointed out that the single-size vent (I don't know what it's really called) is a serious fire hazard because it's going through the new wall (it looks like it was cut out with a butter knife - not very attractive). Everything I've read so far talks about having a B-vent go through a wall with a 1" buffer, but doesn't even mention the single vent size.
When I mentioned this to our contractor, who has 29 years experience, he said he has never heard of that and had no idea what I was talking about.
Can anyone give me more understanding of this issue so I can make sure the job is finished safely? If our contractor, who we trust to know this type of thing, doesn't know it, I want to make sure I'm super clear on it and that the furnace guy wasn't just trying to earn himself some new business (my gut tells me he's actually the one who is right).
The furnace repairman didn't mention how close the wall was to the big fat vent (I think it's the air intake vent), so hopefully that means it's OK, but would appreciate any comments on that, too. Thanx so much!
Here is a link to the pics.