My gas hot water heater's flue/vent is very hot to the touch. Is that normal? How hot should it get?

  • 2
    Really hot, enough to burn the crap outta ya...
    – Jack
    Aug 29, 2015 at 4:21
  • And that's pretty hot!
    – ojait
    Aug 30, 2015 at 21:56
  • Does anyone have a temp gun to get a quantifiable measurement in degrees that can be used for diagnostic purposes? Mar 12, 2023 at 23:54

1 Answer 1


As you just noted gas exhaust flues get "pretty hot". Which is the reason they should not be in contact with combustible material. Also they need to be 'double walled' if they are passing through an enclosed surface. Also be sure the vents terminate to the outside, but not in close proximity to any windows or return air registers.

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