Does poor venting mean a failing water heater

Discussion in 'Water Heater Forum, Tanks' started by nrmedic, Aug 31, 2011.

  1. nrmedic

    nrmedic New Member

    Messages:
    3
    Location:
    Longview, TX
    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.
  2. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Its a sign of poor venting. Had a few with pipes filled with crud down to about a 2" pipe. Pull a brush through it or change it out.
  3. nrmedic

    nrmedic New Member

    Messages:
    3
    Location:
    Longview, TX
    Ok. Just disconnected the vent pipe. Clean with no obstructions. Roof vent also clean. Prior to this I turned the temp up so the unit would heat up. Let it run for 5 minutes and did the flame test at the vent hood. The flame blows away and not drawn in. Any thoughts?
  4. nrmedic

    nrmedic New Member

    Messages:
    3
    Location:
    Longview, TX
    Also I have noticed over the past couple of years there is a light coating of this sediment that accumulates on top pf the tank. Not a soot but more like sand in appearance and texture. Think it is rust?
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,129
    Location:
    New England
    If the flue doesn't draw, you need to resolve that, as you're likely dumping exhaust gases into the house which if they don't kill you, can make you sick. Why it doesn't draw properly depends on many things: size, length, height relative to the roof peak, prevailing winds, whether there is actually enough make-up air, and probably things I've not listed.
  6. Dana

    Dana In the trades

    Messages:
    2,915
    Location:
    01609
    Depending on duct design & leakage, it's often the case that running the whole-house AC can put the basement under negative pressure, sucking outdoor air down the water heater flue. Try your backdraft test with the AC and all bath fans off and see if it then drafts correctly. The solution may be to seal the air conditioning ducts.

    Also, most atmospheric-drafted HW heaters use 3" vent, not 4". What's the BTU rating of the burner (or the model name/number). Oversizing the vent can also result in crummier flue draft. That might cause excessive "spillage" at the vent hood on startup before the flue came up to temp, but that alone wouldn't cause air to be pulled down the flue when the HW heater is firing. Sharing the flue with another appliance can be legal if done right, but is less than ideal.

    Since the thing is in a closet, what provisions have been made for providing combustion air?
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