Nick, you were taught well!

Actually guys, this has been discussed on this forum before. Yes, it is the combination of reflected light off the glass in conjunction with tight siding. On broad walls, they use full panels. When they do make cuts, it is to one side only. They only negotiate one corner channel at a time. Now, with chases, they have to make more precise cuts, don't have a lot of room to nail (maybe two nails per course) and they are frustrated with having to think. I find the side panels snapped in they are cut so long. The few nails sometimes are fully driven in to keep the siding from bulding out. The sunlight phenomenon is usually on southerly exposures.

Ron, if you can read any degree of heat differential on the side of a chase that can be directly attributed to a hot flue or fireplace, you probably have other problems. The testing allows a maximum rise of interior surface temps. of 90F above ambient at the stated clearances. These sides are usually a foor or more away from the unit, thus are usually much cooler. For enough heat to migrate through would mean something is really wrong such as gaps in the sheathing, a disconnected vent or overfiring fireplace.

Good pickup Nick!
Bob

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disgusted with some people on this forum. Out of here!