Rusted/corroded water heater vent pipe


Old 01-21-19, 04:17 PM
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Rusted/corroded water heater vent pipe

Hi there. We purchased a house a few years ago that is an older home that had gone through several remodels over 90+ years (some good, some bad).

Anyway, I noticed the other day that the galvinized vent pipe from the water heater in the basement was severely rusted and corroded at the point that it enters a chimney to vent. The water heater itself is located about 8 feet from the chimney and the vent extends mostly horizontally (but properly pitched, I checked), then does a 90 degree turn, then runs into the chimney. Total run for the galvinized vent pipe is about 10 feet until it enters the chimney where it presuably goes out through the roof all the way from the basement. The chimney itself is no longer in use and I cannot find anyplace where a fireplace or anything was ever hooked up to it. There are no other appliances (e.g., furnace) hooked up to the same vent or to the fireplace. The rust and corrosion occurs only at the point of entry to the chimney and not any closer to the water heater itself.

I replaced the corroded pipe with a brand new one and everything looks ship-shape, but I just want to make sure I'm not missing anything. Should I be concerned that, for example, the chimney itself is not venting properly (clogged or something?) and call a chimney sweep or something? Is it likelier that maybe it was just a little rain pentration into the chimney itself and thus not a concern? I have no idea how old the pipe itself was. It was severly rusted and corroded (I could peel that part apart like paper), but the water heater itself was installed in 2013 with permits so I'm assuming that the vent pipe was at least not visibly corroded at that point (if not brand new).

Should I be concerned, or is this something more along the lines of "Watch it to see if it continues to rust and you might need to deal with chimney moisture or replacing the vent pipe every few years (it was fairly easy to replace, so I'd be fine replacing it every few years, but I don't want to be in danger or something when it appears it is fine/not rusted).


Old 01-21-19, 05:16 PM
Join Date: Oct 2013
Location: United States
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There are different gauges of sheet metal pipe. For regular heating supply pipe you would use 30 gauge which is a thinner gauge pipe. For smoke pipe to vent appliances you want 26 gauge which is a thicker gauge.

As far as rusting it could be just moisture in the chimney because gas water heaters do not exhaust a very high temp gas so the chimney may not have a chance to heat up very well, especially with that being the only appliance going to it.

If you feel uncomfortable then you can have it checked but if that little rust is your concern and not knowing the history of it I would just keep an eye on and go from there. Exhaust pipes do wear out like everything else.

Hope this helps a little.

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