I'm Too Old for the Draft
January 18, 2010 12:49 PM Subscribe
Is it safe to insulate around the crawlspace exit point for a hot water heater vent pipe?
posted by Gingercat to Home & Garden (4 answers total)
We have a one-story house with crawlspace. The tankless hot water heater exhausts to a standard aluminum vent pipe that runs underneath the house to an exit hole in the foundation, bends upward after it exits the crawlspace, and runs up the side of the house. The hole in the foundation is a couple of inches larger in diameter than the pipe, leaving a gap for drafts.
The crawlspace has more than enough ventilation, so I would like to put a small amount of insulation around the vent pipe to seal the gap. I think (but am not sure) that the pipe is primarily a vent for combustion byproduct rather than heat, so I should be able to just buy a small piece of insulation to wrap around the pipe and fit into the gap between the pipe and the concrete, but will doing this cause any problems and/or is it safe to do?