Shutting down natural gas water heater for 2 to 3 weeks

Discussion in 'Water Heater Forum, Tanks' started by BobS0327, Dec 27, 2011.

  1. BobS0327

    BobS0327 New Member

    Messages:
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    Location:
    Maryland
    I have a GE Power Vent, Model GG50T06PVT natural gas water heater. I plan on going on vacation for two to three weeks and I will shut the water off to the house at the main shutoff. I also plan to turn the power off to my GE natural gas water heater.

    Thus, my question is: Will shutting off the water and electric to my natural gas water heater for two to three weeks cause any potential issues? Also, will I have any potential issues upon returning from vacation and turning the water and electric back on to the water heater?

    Thanx
  2. hj

    hj Moderator & Master Plumber Staff Member

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    None as long as the heater does NOT decide to start leaking while you are gone.
  3. Chad Schloss

    Chad Schloss Member

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    Location:
    USA
    hate to rain on his thread, but my question is similar: is is better to drain the heater or leave it full with the water off? I am renovating that house i am working on and hooked up a similar water heater and have it filled with water. i have turned it on once in awhile to make sure it still works, but i have been leaving it off, since i have no use for the hot water yet. is it better to keep water in the tank to stop it from rusting? would it be better to leave it on the vacation setting or have it shut off? thanks :)
  4. cacher_chick

    cacher_chick Test, Don't Guess!

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    If you are leaving for only 2-3 weeks, I recommend leaving it alone. Turning it off or draining it would be more likely to cause harm than good.

    The standby losses on the water heater are very small. With no water use, it costs very little to keep the water in the tank hot. There are several downsides to shutting things off. Anytime a system loses and regains pressure, it will loosen particles in the piping sytem. Tanks and piping with exposed iron will experience accelerated corrosion when drained. Turning the heater down or off can promote growth of bacteria and/or diseases such as legionnaire's.

    In most cases it is best to just close valves supplying appliances with hoses such as a washing machine.

    A good neighbor or service to check on things once in a while would be a better idea than shutting everything off.
    Last edited: Dec 27, 2011
  5. dlarrivee

    dlarrivee New Member

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    Location:
    Canada
    I think if you drain the hot water tank before leaving for a week, you should start wearing a tin foil hat as well.
  6. Gary Swart

    Gary Swart In the Trades

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    I have a GE/Rheem power vent and it has a vacation setting on the thermostat. As others have noted, it costs very little to keep the water hot when none is being used. I'd use the setting provided by the manufacturer for this purpose. Even if you didn't turn the 'stat down at all, the cost of maintaining the temperature would be so small I don't think you could buy a cup of coffee with the savings.
  7. ballvalve

    ballvalve General Engineering Contractor

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    Location:
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    So lets leave our lights all on by the same philosphy. Parasitic losses in transformers and TV's etc. earthwide could heat Russia for a year.

    Since most water heaters have hot surface igniters or spark igniters, turning them off is the same as a light switch.
  8. leave it alone

    it would be wiser to just set it on low
    or vacation, even with the water to the house off
    it wont hurt anything...

    Ge powervents are not the easiest things to get parts for
    especially when you get home from vacation and want to
    take a hot shower.....

    So when you turn off something like a GE power vent
    you run the risk of it just decideing not to jump back
    to life when you come home.....then you are in for some fun.

    also, you would have to be nuts to drain it

    leave sleeping dogs lie......
  9. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

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    Location:
    Houston, Texas, United States
    LOOK AT THIS ABOUT WHAT HAPPENS WHEN HOT WATER IS LEFT FOR A COUPLE OF WEEKS


    Every reader of this column is intimately familiar with cow tipping and, undoubtedly, spontaneously combusting bovine mammals. For the following twist on that same theme, I need to thank Lt. Phil Lyons, Fire Prevention Officer and Investigator with the Tukwila Fire Department, for sharing an article with me on the killer in our kitchens disguised as a dishwasher. Yes, a dishwasher - a potentially murderous dishwasher. It seems a U.S. Navy housing inspector was doing a routine bi-monthly check on vacant buildings at his base. His normal routine was to flush the toilet and run the dishwasher while he proceeded with the rest of the inspection.

    But on this particular day, three minutes after he started the dishwasher, it exploded. The appliance was driven across the kitchen, damaging the plumbing, cabinets and wall; plus it blew apart the rear door of the building.

    Investigators initially surmised water in the "P" trap had evaporated, allowing sewage gas to enter the dishwasher and explode. Methane gas produced by decaying vegetable matter has been known to combust on occasion when it leaks from sewage systems. Alas, methane was not the problem they soon discovered.

    According to the article, one of the investigators found a little-read paragraph inside the owner's manual about hydrogen-gas production in hot-water systems.

    It seems hydrogen gas can, under certain conditions, build to unsafe levels in systems that have not run for two weeks or more.

    The investigating engineers explained that because of the way the hot-water-heater tank was constructed, there was no way to stop the production of hydrogen gas.

    Hydrogen isn't water soluble, and it remained in the plumbing system as a gas under pressure.

    The gas normally migrates to the top of the plumbing system, where it is drawn little by little from faucets, thus becoming part of the greater atmosphere.

    In homes where the hot water is not drawn regularly, and a lower-level faucet or appliance is used first, the gas is forced out at that level.

    The theory behind this explosion was that the hydrogen was ignited by the timer or relay switch inside the dishwasher because hydrogen gas has an extremely wide range of flammability and will explode at just about any mixture, if a source of ignition is provided.

    This was the first exploding dishwasher on record. People in the water-heating industry say that a washing machine is known to have exploded in the 1960s.

    And several small fires at faucets have occurred when hydrogen gas was relieved next to a burning cigarette.

    Safety investigators recommend that occupants who have been away from a building for an extended period of time first run their hot-water faucets to relieve gas. And they should not smoke while doing so.

    The article did not say whether turning off a hot-water tank that isn't going to be used for several weeks eliminates the problem.

    Is this heat-related, or a chemical reaction that happens whether the water is hot or cold? Readers, share your knowledge, please.
    Last edited: Jan 3, 2012
  10. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    Hydrogen gas is an old time bomb in unused, running water heaters. Some do it and some do not, but its influenced by the water quality and the type of anode rod.

    Best and smartest to shut them off. And leave the water in.
  11. Runs with bison

    Runs with bison Member

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    892
    Location:
    Midwest
    My advice, leave it at the normal set point, not on vacation setting, not empty, not off.

    Here is why: legionella bacteria thrive at the lower temps. Their ideal growth range is 95-115 F, and that appears to be precisely where the "vacation" settings will put it for several days as it cools off.

    I'm all for saving energy, but from what I've measured with a less efficient standard gas water heater the loss is about 1 ccf/gas use per 10 days when nobody is home and the water heater is left at normal setpoint.

    Related topic: timers for water heaters. I have the same issue with them. If the timer doesn't allow the tank to reheat after use, then the tank water temperature will stay in the danger zone for hours, perhaps 8+ hours. The timer will save very little energy in the process. Timers make economic sense for electric water heaters using with on/off peak rates. It's not about saving energy, but reducing charges for peak hour usages. And electric water heaters have much lower standby losses AND a much greater propensity to grow legionella in the first place.
  12. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    How many homeowners died of of legionnaires disease from hot water heaters this year?. Your home heater is not a Holiday Inn ballroom with miles of mouldy ducts and dirty filters.

    And if its so, those folks that throw money in the toilet for tankless heaters should drop like flies since their water is always in cooling off stage in the pipes and heat exchanger.

    There are millions of homes with 'open' - mine included and countless others I have installed- radiant heat systems where the hot water is constantly cooling to 50 or 60 degrees, being reheated, and often making it to fixtures at 115'. Havent had any lung, heart, asthma, disease or sudden deaths reported.

    So they took the lead out of valves, now the gov will make us keep our water at 150' f to "save" us.

    And here is the beginning of the BULL$%&^ dreaded OSHA wants us to test, never shut off a circulator pump, and eventually ban flow thu heaters. Just what we need.

    http://www.osha.gov/dts/osta/otm/legionnaires/hotwater.html

    They actually want the water in a hot water line to NEVER drop under 122f. Go for that plumbers!
    Last edited: Jan 7, 2012
  13. Runs with bison

    Runs with bison Member

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    892
    Location:
    Midwest
    More than 1 for certain, since there are between 8,000 to 18,000 cases of the disease estimated in the U.S. each year, and most homes have a water heater. In hospital settings the fatality rate is calculated as 28% and the source is primarily the drinking water (the same water that enters your water heater.) Various sources give the fatality rate as 5 to 30%. So a moderate guess would be around 2,000 deaths a year from the disease. Take your own guess as to how many came from water heaters.

    According to OSHA: "Domestic hot-water systems are frequently linked to Legionnaires' outbreaks."

    And from a study done in Quebec: "Domestic water heaters, particularly electric devices, can certainly be contaminated by Legionella. In Quebec, a study of 211 homes (178 electric water heaters, 33 oil or gas water heaters) found Legionella contamination in 40% of electric water heaters. No water heaters using fossil fuels were contaminated."

    My experience designing, operating, and troubleshooting reactors suggests the opposite is true. The water in the tankless is going to get nice and toasty running next to heat transfer surface that tend to kill such things, and/or not sit around for more than a few minutes in the danger zone. Water in primary supply lines cools off quickly when not in use and is called for frequently (very high turnover rate), so legionella in "stagnant" lines is not a major concern to me.

    However, a water heater is a terrific biological reactor if conditions are right. Residence times are on the order of a day. So if there is any legionella in the incoming water, it will have the opportunity to propagate.

    I would have to look at the design of the radiant system and see how they actually operate before I would commit one way or another. I don't have experience on this type of domestic system.
  14. ballvalve

    ballvalve General Engineering Contractor

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    Location:
    northfork, california
    Can america afford another set of regs that double the cost of plumbing and gas use? will we need silver lined water heaters and pipes? Every fixture on a hot recirculate full time? NOBODY died from a brass valve last year, but thats all going federal this year.

    Firesprinklers. Bad enough, now they will need full recirculate lest something grow in the pipe and someone breathe the mist when running from the home.

    Better build more overpasses and shopping carts - on a hot day the new hourdes of homeless can catch a shower from warm condensation dripping from the girders.

    Finally, they MUST ban swamp coolers as they are a proven receptacle for legions of leggionaires type microbes. Thats about 80 million people west of the Mississippi without cooling now. They drop dead pretty regular around here. Get the ACLU on it.
  15. Runs with bison

    Runs with bison Member

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    Location:
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    I'm not buying into the hysteria/strawman, because that is not what I'm seeing and it has nothing to do with topic of legionella in a tank or tankless water heater. I don't see plans for recirculating every fixture.

    As for removing some lead from fittings, big deal. It isn't going to bankrupt us any more than low flush toilets, removing lead from other plumbing parts, higher efficiency AC's, furnaces, water heaters, TV's, banning CFC's, etc. have. I see opportunties for new U.S. products, rather than trying to compete on thin/negative margins in commodities (but good luck trying to convince conservative U.S. execs to invest in R&D, they are running their companies like dodos...headed down the same path to extinction.)

    Your lead argument is the same sort of one that would be used for lead plumbing, leaded gas, lead in paint, controlling emissions from lead smelters, etc.
  16. ballvalve

    ballvalve General Engineering Contractor

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    3,261
    Location:
    northfork, california
    When one surfer hippie proves lung disease from his Santa Cruz beach shack water heater, California will pass a proposition that will go federal in 3 years.

    We legislate lead from the US manufacturers, but never open a container of poison from China at the port. So how CAN they compete? Our manufacturers are not the dodo's, its the feds who do not protect them with our "one world of trade". Good on them, IF they pay to inspect the imports to standard. No one has the balls to turn a few thousand containers around - that would get some attention, and suddenly the incoming parts would be costing the same as the US version.



    This from last week, 3 major factories relocating to the US because of transportation, fuel cost and even labor costs in other countries including China, mexico and Canada.

    http://online.wsj.com/article/SB10001424052970204331304577142983208038646.html
    Last edited: Jan 9, 2012
  17. Runs with bison

    Runs with bison Member

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    Location:
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    Let me explain it to you: they (corporate geniuses who now run our tax policies and have done such a great job of zero f'ing growth over the last decade while blowing a huge hole in our budgets) gave away all of our manufacturing tech to the Chinese a decade ago. We (as ordered by our conservative corporate masters) were teaching them how to make things using tech they didn't yet have. Their govt. is way smarter than ours and light years ahead of our idiotically selfish and short-sighted corporate bozos. They think Sun Tzu, our guys are more like Yosemite Sam. The Chinese insisted that to sell into their markets we: 1. Had to build the plant there (not in neighboring countries either...killed some of our projects.) 2. Had to staff it (including engineers, supv. etc.) with Chinese. 3. They had 51% ownership. 4. We gave them the tech. 5. Their design institutes built the equipment. 6. We had to teach the design institutes the basic so that they could do step 5 (they were f'ing clueless, because they had no experience with stuff that was industry standard to us.)

    It was a deal I would have laughed at and walked away from. But not our wheeler-dealer smartest-guy-in-the-room types (they loved their Enron!) They drank the kool-aid. Within about three years the same dumb-asses at my company threw away $2 billion of our our $5 billion of net worth in similarly cock-eyed ventures around the globe. (They were stupid in a multi-cultural way.)

    You are mixing your bases. California doesn't have authority over imports, the Feds do. If Cali did you can bet they would be hard as hell on the Chinese. Their reach is limited to what happens in the border of their state. California would have everyone working for a living wage, you'll never see than in any conservative state. Conservative states are fond of slave wages. They are trying to figure out how to pay folks like the chinese, while getting U.S. efficiency out of them.

    Thank God for Soc. Sec. and Medicare because corporate retirement and health benefits are mostly gone. U.S. companies have fucked this nation over good. Outside investment savings? HA! Negative returns for a decade or more. U.S. retirement investing is all set up to reward banksters and hedgefund managers. Rip off of the century.

    Regulated free markets work. Unregulated ones don't...hence the past decade. Unregulated free markets drive toward giant monopolies and enrich the wealthiest while taking from everyone else. And that is all we've seen for the past 12 years. Yes, I include the current administration in this as they've continued the same business conservative Bush policies that got us into this mess.
  18. Dana

    Dana In the trades

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    In a tankless 100% of the water is purged and replaced with much colder (==less contaminated) water on every draw. With any tankless the temp drops well below the prime growth temps for legionella within a couple hours of the last draw. This is a VERY different scenario from maintaining a large volume with a large surface area at 115F, where the volume of water is almost never purged in one go, and stagnates at temps for many hours at a time with no flow.

    In most residences the hot water distribution system spends most of the time below the prime breeding temps for legionella too. The prescription for higher temp distribution temps would only be relevant for systems where flows are higher in frequency and the temps of the water in the plumbing falls into the range between flows. At 50C/122F the legionella isn't killed, but it colonies can't grow.

    The open system radiant floor situation has real potential for problems if allowed to stagnate. Open systems are only allowed in MA if controlled for a minimum guaranteed flow every hour, even outside of the heating season. It's much tougher for cultures to get established and grow if the water is moving, and while a purging flow pattern during the off season can be guaranteed by design in an open system it isn't always. I'm sure there are open systems that should be condemned as a health hazard, but I'm just as sure that many or most will never have a problem. Simply asserting that there haven't been any lung, heart, asthma, disease or sudden deaths reported is small comfort, given the pervasiveness of Murphy's Law. (How often can you identify the exact source when you get sick?)

    I'm skeptical about the "millions of homes" number for open radiant systems. Really? Millions? Do tell! If 2% of the homes in the US have radiant floors, and 2% of those are radiant systems it's still less than 200K homes, and I suspect the real numbers are lower than that. The majority of heating systems in the US use ducted hot air distribution, and all hydronic systems combined comprise at most half of the rest. Most estimates put all hydronic systems (not counting steam) combined at between 3-7% of all heating systems (trending downward over the past decades) with radiant floors being a small fraction of that. Radiant systems would have to compromise a large fraction of the radiant heating systems to number in the millions. In 2010 all hydronic systems combined (including steam) comprised well under 10% of the US market for new construction. See: http://www.census.gov/const/C25Ann/sftotalheatsystem.pdf http://www.census.gov/construction/chars/pdf/soldheatsystem.pdf Where is the case for "millions of homes" with open systems? Tens of thousands, maybe, but even that may be an order of magnitude too high.

    People who are at risk for contracting legionella from contaminated systems are people who are already have compromised health, particularly those with pulmonary issues. Quitting smoking will lower the risk by a greater degree than maintaining tank temps at 50C or higher. Purging the distribution pluming with 60C/140F temps a few times per year is enough to kill off any colonies that get started. (With many staple-up radiant open systems that will happen regularly as a matter of course during the heating season, not so much for slabs.)
  19. ballvalve

    ballvalve General Engineering Contractor

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    Location:
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    he
    The so called "L" disease was discovered in ducted hot air systems, and i still feel "sick" house syndrome when I spend time in older ducted homes. Take a look at the crap in the old pipes, you'll never duct anything again. I started out stupid, all caps, removing asbestos wrapped pipes in basements of midwest homes for my uncle, and no one ever heard of a mask then. coughed up black crap all night. Probably heading for the asbestos lawsuit sleazebags soon, although my uncle in his 80's is still healthy.

    I heat one house electrically, open radiant, and when at rest it sits at 150'f, so i suppose that jolt give the germs a pause. But when circulating, the temp of course falls near 120 and 115. Maybe I'll drop a pile of my silver dimes into the heater next time I open it. Or hang them on the anode.

    But all in all, I think we are on a witch hunt that may lead to another round of regs that finish off housing altogether. But where are all the dead people with appropriately names "swamp" coolers? ever live in a swamp?



    Look, I agree completely with the corporate greed, lack of guard of our knowledge base, and base stupidity of selling and giving away our hard won MFG. systems. But we started with the JAPANESE, to "rebuild" them - screw them, let them eat cake. Then the Marshall plan that gave Germany the machines to sell parts to Iran and Pakistan to build the bomb.

    Then we PAID the Russians for their nuclear clean up, the richest and poorest nation all rolled up in one.

    The bean counters at the big industries that sold our knowledge to the chinese should be strung up by the nuts. But in their defense, if we had not, the germans or italians or french would have done it anyway.

    And we build schools in Afassisthan, while being shot at. Here at home our teachers are on food stamps and havent had a job in years. And i know many teachers, and 2/3rds of them could'nt find their way out of a paper bag. And all the metal and wood shops went away because baby johnny might cut his finger. What the hell good is knowledge of kicking a ball around a field to a 25 year old unemployed dope?

    On the upside, industry REALLY is coming home, and even the japs are starting to rethink that little rock they sit on, ready to fall under water. Honda is moving most production here. BMW EXPORTS from the USA.

    And the USA still beats all hands down for manufacturing output and capacity. The next time that moron that runs Iran gives a speech, rather than throw a shoe, lets put a cruise missile up his navel.
    Last edited: Jan 10, 2012
  20. Dana

    Dana In the trades

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    Sorry to read about your asbestos exposure, and if it's affecting your lungs it probably makes you more susceptible to legionella (amonst other things) than most.

    Ducted air distribution may be a major method of spreading legionella in some well publicized outbreaks, but getting the legionella into that air isn't likely in most residential systems. Ducted air with humidifiers or routed where there's condensation potential can be major mold spreaders though. Showering in legionella contaminated water would a real risk for the susceptible. The fact that you park the system water at 150F is probably highly protective in your open system- the tank can't become contaminated, and will in fact kill any legionella that finds it's way in, even if the radiant loops run near the critical temp range. In the off season temp of the water feeding through the floor is probably well under the critical temperature range. And if it's plumbed as a flow-through that guarantees that all radiant loops get fresh water during hot water draws, the risk of stagnating water growing anything in side loops is small.

    The risk from parking the heater at 100-110F for only a few weeks is also pretty tiny, if it's normally set to 130F or more. It takes more than a couple of weeks for a colony to become established, and cranking the temp back up to 130F would slowly kill anything that got started. It's the folks that run their tanks at 110F forever to save on standby losses that are more likely to get something going. Extensive time stagnating at colony growth temps and never reaching killing temp is the issue. But even those folks may be at low risk if they're generally healthy, don't smoke, and tub-soak rather than shower.
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