Newbie here. I have searched the web but cannot find a straight forward answer so wanted to ask y'all. I have 2 water heaters but noticed last week that the closet the NG one is in is very hot. Have not checked my vent pipe yet for obstrution but will tonight. I will also try the lighter test to see if the flame draws into a the vent. So if there is no obstruction in the pipe could poor updraft be a sign of a failing water heater? It is 13yrs old but never have any problems.ater is hot and plenty of it, never run out. Now I live in Texas and we are having record heat this summer so could that affect the updraft? There are days it's been 113° so I know it is hotter on the roof. The vent pipe is 4" metal and goes straight up to a dedicated gas vent out the roof. All of the websites I've read mention vent pipe obstruction but don't address what else could affect a normally well venting heater. Thank you for your time.