Shut off water with gas water heater

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by ddagsyn, Mar 26, 2008.

  1. ddagsyn

    ddagsyn New Member

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    50
    I have a two storey with the gas water heater in the attic. When I go on vacation I would like to shut the water at the main but not turn off the gas water heater.
    Will this cause any issues? The heater will be full of water as i don't plan on draining any water. It is a bradford and i don't have a vacation setting on it. The only setting are "Pilot lighting" "ON" "OFF" and a dial to regulate the temperature of the water.

    Thanks
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Probably not a good idea! If for some reason the tank leaked or was siphoned dry, it would call for heat and burn itself, and maybe the house. It should turn off if it got too hot, but would still probably self-destruct.

    Whenever you turn the water off, it is a good idea to turn off or at least turn it to pilot on the gas WH. Also, if you live where it can freeze, turning it off could allow it to freeze, which would also ruin it...and if it thawed, do major damage to the house.

    Taco makes a mechanical WH leak/shutoff detector safety device they call WAGS. This can both shut the water and gas off to the WH if the sensor gets wet. It can be retrofitted, but may be a good thing for when the WH is replaced the next time.
  3. Ian Gills

    Ian Gills Senior Robin Hood Guy

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    Very interesting thread. My Bradford has a vacation and a pilot setting. What is the point of a vacation setting? Why not just leave the pilot on when going on vacation? It is a lower setting and would use less gas.

    Is it because of the freezing issue mentioned above?
  4. ddagsyn

    ddagsyn New Member

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    50
    there is no freezing problem in my area. My concern is having the water on when on vacation.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    If you don't have a possibility of freezing and you wanted to turn the water off, I'd probably just turn the burner control to pilot. That way, the main burner won't come on, and you only need to turn the valve rather than trying to relight it when you come home.
    Keeping the pilot on keeps moisture from accumulating in the burner (condensation, etc.) that might occur by keeping it slightly warm from the pilot light.
  6. Redwood

    Redwood Master Plumber

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    I do not advocate turning off the heat on a water heater. This will increase the danger if Legionaires desease.

    The biggest single threat from tepid water is probably legionella.

    70 to 80 °C (158 to 176 °F) - Disinfection range
    At 66 °C (151 °F) - Legionellae die within 2 minutes
    At 60 °C (140 °F) - Legionellae die within 32 minutes
    At 55 °C (131 °F) - Legionellae die within 5 to 6 hours
    50 to 55 °C (122 to 131 °F) - They can survive but do not multiply
    20 to 50 °C (68 to 122 °F)- Legionellae growth range
    35 to 46 °C (95 to 115 °F) - Ideal growth range
    Below 20 °C (68 °F) - Legionellae can survive but are dormant

    http://en.wikipedia.org/wiki/Legionella

    [video=youtube;9E-u5YNi8B4]http://www.youtube.com/watch?v=9E-u5YNi8B4[/video]
    Last edited by a moderator: Jan 28, 2011
  7. hj

    hj Moderator & Master Plumber Staff Member

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    heater

    Your heater does have a "vacation" setting it is just not marked as such. To get it you rotate the temperature dial to its lowest setting. A better policy because there could be many things that could occur is to turn the dial to PILOT, then there is no chance whatever for the burner to ignite. Especially with the heater in the attic, since there are certain conditions that could cause it to lose all its water through siphonage.
  8. Ian Gills

    Ian Gills Senior Robin Hood Guy

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    Which stands completely at odds with recommendations, which quite clearly state that my hot water should be no more than 120F, and on my heater it is set to this.

    Does this mean that we should all be using mixer valves, and setting the temp so high we dribble from the TPR valve?
    Last edited: Mar 27, 2008
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
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    The city where I live requires all newly installed WH to be plumbed with a tempering valve. They can only recommend you set the thermostat high enough, they do not mandate it. Local (and probably national) codes are changing, and it can come as a big surprise (both monetary and material) when it comes time to replace the WH.
  10. Redwood

    Redwood Master Plumber

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    There are a few states in the US and I believe Provinces in Canada that are requiring a setting of 140 Degrees F and a tempering valve mixing it back down to 120 degrees F for scald prevention.

    I would say before long it will be widespread!
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