Combustion Safety Rule #1: Remove Exhaust Gases from House
So, I was out on a field test with a new HERS rater the other day, and we took a look up in the attic. The scuttle hole is right next to the closet where the natural gas water heater lives, and the flue comes up into the attic right there where we poked our heads up. The photo at left shows the flue pipe going up and then making a turn before exiting the roof.
See that little offset there right above the turn? If it looks like it's not making a good connection, that's because it's not making a good connection. In fact, when the new EVER rater went up there first, it looked worse than what you see here because he'd already put the two sections near each other when I got a chance to take the photo. You can see a little better in the photo below right that even though those two sections are near each other, they're not connected.
Yeah, this is happening in a vented attic, not inside the building envelope, so why worry about it, right? Wrong. You want those exhaust gases to get all the way outside the house. You don't want them in a buffer space like the attic because it's still likely they could find their way into the house. Exhaust fans and clothes dryers can cause the house pressure to go negative relative to the attic and suck those flue gases into the house, for example.
It's amazing how blatantly obvious so many building science and combustion safety problems are once you know a little bit about how things work. Actually, you don't even have to have any training to know that when a pipe is supposed to be carrying something from point A to point B, it has to be continuous for the something to reach point B. I wrote an article about duct leakage last year that shows some obvious problems that take only a pair of eyes to find.
The field test went well, though, and Luke Bertram of Green Summit Consulting is our newest EVER rater. He took our HERS rater class in February and was one of the lucky ones to have his training and certification costs covered by ARRA (Stimulus) money. The City of Doraville, Georgia is really on the ball and is getting people trained to provide subsidized energy audits to city residents. Here's Luke in his Tyvek suit, about to enter the cave of mystery (aka crawl space) under the test house.