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Thread: 120F not hot enough?

  1. #1
    DIY Junior Member HoracioO's Avatar
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    Default 120F not hot enough?

    For a long time I ran my hot water heater at around 120°F thinking I was saving energy. My front loading clothes washing machine would always have an odor no matter how much it was cleaned—dishwashing powder, bleach, then those "tablets"!

    So I increased the temperature in the hot water heater to give it a good solid cleaning. I forgot to turn it down, but after a few weeks I remembered and I also realized that the washing machine no longer smelled!

    Six months later no smelly washing machine!

    Then I read: The case for very hot water

    Which pretty much made the claim that:

    “The number one cause of waterborne disease outbreaks in the United States,” says environmental engineer Marc Edwards, “is not contaminants leaving the water treatment plant (we do a good job of killing those). It’s the pathogens that grow in home water heaters.”
    My experience seems to support the theory, So what do you think?

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    I tend to agree from what I've read, but then I've not read extensively on this. I do run mine at 140 and at this temp, you should have a tempering valve to drop the output. Many dishwashers have auxilliary heat to bring the thing up to temp, but few washing machines in the US do. There's a push to only wash in cold, but I'm still not convinced that's the best for all stains and fabrics. There's a discussion on this in the Tankless section.
    Jim DeBruycker
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    DIY Senior Member Runs with bison's Avatar
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    This was a "bait and switch" thread: I'm still trying to figure out how changing the water heater temp changed the cleaning of the clothes... Don't know about anyone else here, but we don't wash our clothes in HOT, and AFAIK the "warm" setting is temperature adjusted on our front loader.

    Okay, ignoring that and taking the bait, there are some logical fallacies in the link, etc. First of all, those bacteria are NOT growing at 120. Somewhere below that, yes. At 120? Not really. It does not "provide a nurturing environment", that's just a bald faced lie!

    Second, the article quotes that it "is not contaminants leaving the water treatment plant (we do a good job of killing those). It’s the pathogens that grow in home water heaters." That's obviously a lie. It is either coming from the facility or through the distribution system maintained by the same entity that runs the facility. It isn't spontaneously appearing from sterile water in the heater. From the study of showerheads it was noted that residential wells didn't have the problem. Ponder that for a minute.

    Third, unless you routinely run your showerhead hot only at 140+ F, you won't actually kill the colonies there and they will instead spend 95-99% of their existence at temperatures more amenable to their existence.

    Fourth, there is a move toward tempering valves...with them you will never have 140 at the showerhead and instead will max at 120. You don't kill the legionella until you hit ~150.

    So what was the point again????

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    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    That article is basically making a link between the HWT and the disease but it even says that going up to 140F isn't going to do the job and that no study had been done at that temperature yet.

    So my theory would be if you're gonna get sick you might as well get sick for as cheap as possible and run your tank @ 120F. If you're really concerned then flush your lines with chlorine and install a UV filter on you main coming into the house.

  5. #5
    DIY Junior Member HoracioO's Avatar
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    Not sure why you would call this a "bait & switch" thread?
    I'm interested in hearing opinions as I was some what surprised about the claim (having been running at 120°F for years) but in the case of our front-loader washing machine it seemed to do the trick. I'm not talking about washing clothes at "Hot" just doing the occasional load on hot or doing the monthly machine cleaning. For 5 years we had an "odor issue" and a build up of rusty colored mold on the rubber gasket, all approaches seemed to fail. My forgetting to turn the heat down after doing a couple of hot water cycles surprised me and then just recently reading the article made me wonder. Keep in mind, the musty odor inside the machine has not retuned nor has the frequent build up of slime on the rubber gasket—and the only variable that has changed is the water temperature from the hot water heater.
    Could I achieve the same thing by doing the monthly washing machine cleaning with hot water from the stove and save myself some money? Maybe, unless there is some merit in the notion of the 120° hot water heater being an aggregator/breeding ground for naturally occurring bacteria/slime/molds...
    Truly wondering...

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    Plumber jimbo's Avatar
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    The logic on your washing machine doesn't follow, unless you are washing clothes in all hot. Do you do that?

    Now, odor in front loaders is a well documented problem, caused by the fact that the lid is air tight, thus not allowing any fresh air to enter the machine between uses. The moisture inside can allow mold and mildew to happen, especially on the big rubber door seal. The solution is to treat the door gasket with lysol now and then, and if possible leave the door ajar when not in use.

  7. #7
    DIY Senior Member Runs with bison's Avatar
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    Quote Originally Posted by HoracioO View Post
    Not sure why you would call this a "bait & switch" thread?
    You started off on one topic then made an unexplained leap to another (the article.) The article had problem with internal inconsistency too.

    I'm interested in hearing opinions as I was some what surprised about the claim (having been running at 120°F for years) but in the case of our front-loader washing machine it seemed to do the trick. I'm not talking about washing clothes at "Hot" just doing the occasional load on hot or doing the monthly machine cleaning. For 5 years we had an "odor issue" and a build up of rusty colored mold on the rubber gasket, all approaches seemed to fail. My forgetting to turn the heat down after doing a couple of hot water cycles surprised me and then just recently reading the article made me wonder. Keep in mind, the musty odor inside the machine has not retuned nor has the frequent build up of slime on the rubber gasket—and the only variable that has changed is the water temperature from the hot water heater.
    Could I achieve the same thing by doing the monthly washing machine cleaning with hot water from the stove and save myself some money? Maybe, unless there is some merit in the notion of the 120° hot water heater being an aggregator/breeding ground for naturally occurring bacteria/slime/molds...
    Truly wondering...
    I've had my front loader through a full summer now, no problems. We leave the door open while not in use, and wipe the gasket and dispenser. These are common knowledge recommendations for this type of machine. Otherwise you run the potential for mildew. I've never even run the cleaning cycle on it.

    There are lots of extrapolations there. Which do you think is likely to be a greater source of bacteria/mildew...your hot water? Or your underwear, socks, shirts, pants, towels, dishrags, etc?

    Top loaders can mildew as well...had that problem with a machine in the humid southeast after a load was inadvertently left in it for several days. Took about six months, some hot loads, partial disassembly to get to soap scum on the plastic tub wall, and mildewcide to completely rid it of the stench. Once mildew takes hold, it is tough to get rid of.

    Hot loads are a rarity for us.

    Will doing your cleaning cycle at 140 F do a better job on knocking down the generic sources of mildew and such that are already there? Most likely. But you can prevent mildew in the machine without bumping up the temp by 20 F.

    I've seen no evidence that bugs are thriving in the water heater at 120.

  8. #8
    DIY Junior Member HoracioO's Avatar
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    Well it was not bait and switch, it was two distinct events, my inability to get rid of the known problem with mildew in my front loader and sometime later seeing an article that made me wonder about how my machine stopped being a problem. I had not assumed the bugs came from anywhere else but washing clothes and the air. All the odor/mildew mitigations suggestions mentioned above were tried, we always kept the door open and we live in a very dry climate. As I said, the only variable that was modified (known to me) was my attempt to boost the cleaning with hotter than normal water (something I had done multiple times before) but this time I had forgotten to set the temp back.

    Given that there are many molds and bacteria out there, some of which can survive quite well in hot water, and even better in nutrient rich washing machines it is not a great leap in logic to assume that there would be a greater number of such organisms at lower temperatures. There might just be a positive correlation between increasing water temperature and reduced bacterial/mildew survival. One does not need to hit a magic number of 150°F to kill bugs, some can survive at 212°F, but the likelihood of such bugs being in my washing machine is pretty darn remote. However as we approach "our" temperature ranges it would be expected that there would be greater number of potential inhabitants—normal distribution.

    So back to my machine. Why would the mildew problem be eliminated by just leaving the the hot water heater at a higher temperature? We don't regularly wash in hot water, so going out on a limb, maybe the hotter water is increasing the temperature of the machines "mix" of cold & hot water by a couple of degrees and that's all it takes for my particular mold issue. This is why I posted here, I found it difficult to explain why raising my HW temp fixed a long standing issue and so it was a genuine rumination.

  9. #9
    Plumber jimbo's Avatar
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    Quote Originally Posted by HoracioO View Post
    This is why I posted here, I found it difficult to explain why raising my HW temp fixed a long standing issue and so it was a genuine rumination.

    Could it be that at the lower WH temperatures, molds or bacteria or viruses were surviving, later to thrive and multiply in the washing machine environment?

    This is a topic which is being studied at local and national levels. There are now AHJ which require 140º WH temp + tempering valve. If IAPMO or CDC or some other national agency eventually issues an opinion, look for futher code changes on the subject.

  10. #10

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    Washer smells--These can be caused by doing too many or exclusive cold water washes. Google that and you will find pics of the crud inside the machines. One of the biggest problems is detergents and liquid fabric softeners. With front loaders it is best to use powder detergents, liquids tend to build up and stick to the outer tub which then causes this to attract dirt and this in turn feeds mold and fungus starting all the stink in the tub.
    Using liquid softeners also worsens this problem because they really tend to cause build-up more than the detergent(waxy). The biggest thing is using WAY too much detergent whether it be powder or liquid. I know LG recommends you use no more than 2 Tablespoons of detergent. When you have too much sudsing in a F/L machine the suds tend to get trapped in places that it cannot get rinsed out and then this starts build up also and causes the smells. This is why machines with a "Clean Machine" cycle fills the tub more so the water will be higher than the normal level when washing clothes. Also, on some machines with the Clean Cycle it also turns on the heater and heats the water to the sanitary cycle temp(over 150 for most machines) so this is why I would say the hotter water from your water heater helped clean the crud and odor out of your washer.

    I use 140 on my water heater also. I used to have it on 120 but I was using more hot for a shower and much less cold. With 140 I am using less hot and it also lets my dishwasher heat up faster than at 120 and I really never noticed any real difference with my power bill----BUT I can remember the days when everyone ran theirs on 150-160 and thought nothing of it. That was just Normal way back then..

  11. #11

    Cool Here's what I think....

    and the really funny thing is about this is, I think EVERYONE is correct in nearly ALL of the previous posts!

    First, I agree with others who have labeled Marc Edward's claim (quoted in post #1), as absolute hooey. The phrase "water-born outbreaks" means multiple cases, multiple houses... it's system-wide. Treatment plant failures, floods, and line breaks are the common causes. And in these "outbreaks", it's not the hot water which infects people-- NO ONE drinks hot water from the taps and fixtures! They're getting infected from the cold water. Lime and sediment deposits "grow" in water heaters. Microbial Pathogens don't.

    But I also agree that HoracioO's experience is real, and it makes perfectly good sense to me. I think that he only got it wrong when creating a "theory" behind the experience. The smelly microbes aren't growing in the hot water system-- they're growing in the clothes washer itself. Here's how: Although the water heater was set to put out 120F, the "hot" water inside the washing machine ends up being much, much colder. In the beginning, the "hot" cycle begins with a bunch of cold water pouring in from the cooled-down supply pipes. Then, when it finally does warm up, an enormous amount of heat is lost into the steel basket of the washer itself (and the valves, and the internal lines, and the clothes themselves). And because an HE front-loader uses so little water, these chilled-down issues constitute a much higher proportion of the total "hot" water being loaded into the clothes washer. (They'd be less significant in a "greedy" top loader, because the top loader would continue taking a lot more pure hot water after all of these losses have ended.)

    So even at the end of the fill, it's definitely not 120F anymore. And as the wash cycle proceeds, the temperature keeps going down. So the microbes survive through the initial "pulse" heat (maybe 110F or so, maybe just 105) and as the temp continues to fall, maybe as low as 100, they're having a party-- it's like a whirlpool bath for the little buggers. Over time, they grow into a big colony and create a mat of smelly organic muck. And once it's grown up, the thick mat further protects them from the initial "pulse" of high temperature at the end of the wash cycle fill.

    In this scenario, bringing the water heater up to 140F brings death to the buggers-- you've got enough heat that even with all the losses in the pipes, valves, basket, and clothes, it's still killing them, and it eats away at the mat over time. Clean clothes washer!
    - - - - -

    I must disagree with just one thing in the post above (from prd823): He's right on the money about using too much detergent, but he might be wrong to recommend powders. In some machines, the detergent-loading compartment gets rinsed many times, and that helps some-- but once the powder chunks have washed down into the basket, HE front loaders use only gravity to agitate the contents, and they must be used with low suds formulas, because the water volume is so small. A regular powder detergent suds too much, and the excess suds don't rinse off properly. Because of the low water volume, HE front loaders also make the washing solution much muddier with dirt and grime-- and the good HE detergents are formulated to suspend the higher degree of filth better. Just as they failed with their own suds, the regular detergents will leave dirt behind-- they just can't keep it suspended. So you end up needing two or 3 rinse cycles, which kind of negates the whole purpose of buying "High Efficiency" in the first place.

    In my washer, which is very high-end, I tried it and looked. Powder remains undissolved for 5+ minutes at high temps, and remains undissolved through the entire washing stage in the cold/delicate cycle. The one which always works well is Tide HE liquid. "All" doesn't work as well. There might be some other good HE products, but my DW needs fragrance-free, and there are very few options.

    prd823 is totally RIGHT ON! about the amount of detergent. With Tide HE, we've found that the best results come from using less than 1/3 the amount of the "normal load" line on the cap-- even though our clothes washer is one of the biggest front loaders which sold for non-commerical use, and even when we've filled it really filthy towels from construction clean-up. It isn't "just as good" as using the Tide-recommended amount: it's much, MUCH better to use far less. Cleaner clothes! Cleaner washing machine! Less detergent down the sewer for water treatment! Less Money! Less Shopping! Less totally wins.

    So my advice is HE liquid, no powders, at about 1/4 the recommended amount. (Just like prd823 said-- in a normal load, that's about 2 tablespoons.) And for you, keep that WH temp up at 140F- you're clearly doing the right thing by leaving it there.
    Last edited by rickst29; 10-27-2009 at 12:52 PM.

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    DIY Member drizler's Avatar
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    Default Another Way To Get Clean Using Cold, Soak It Overnite

    We just discovered this recently but it works like a charm. Just toss in the detergent and leave the lid up. Next morning or whatever flop it down and let it finish. Laundry is a lot cleaner and nothing but cold water.

  13. #13
    DIY Junior Member HoracioO's Avatar
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    Overnight soaks used to be the way... but front loaders have made that just a little tougher when you leave the lid up ;-)

    One could always just use the pre wash cycle and let it sit, but I'd hazard a guess the smelly stuff might make that less than optimal in a front loader.

    That said, I continue to use my "hi temp" setting for the hot water heater and monthly cleaner tabs and we have no odors anymore. After 4 years of always wondering about the odor in the washer I can now sleep easy!

    We only use a small amount of detergent, but I've noticed than when we used Tide it did seem to leave more sticky residue on the dispenser area. We've been using some other "green" brand and it does not seem to be as bad, so maybe that's another explanation!

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    DIY Senior Member Nate R's Avatar
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    Quote Originally Posted by rickst29 View Post
    And in these "outbreaks", it's not the hot water which infects people-- NO ONE drinks hot water from the taps and fixtures! They're getting infected from the cold water. Lime and sediment deposits "grow" in water heaters. Microbial Pathogens don't.
    In the article's defense, they DID cover that.
    Owing to lead-poisoning concerns, people should never drink hot tap water. That’s why the primary route to respiratory disease from these germs comes through inhalation of the steam associated with showering or hot tubs. Infections due to these home-grown germs are estimated to kill 3,000 to 12,000 Americans annually, Edwards says.

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    Journeyman/Inspector Inspektor Ludwig's Avatar
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    Yeah, they found some pretty nasty bacteria living in showerheads and it seems that nothing can get rid of them. The whole idea behind 120 water was scalding. I think now that tempering vavles are required on dual handle bathtub faucets, we might see the 120 go a bit higher but with the whole green machine starting up people are turning theirs down, big no no, that's a legionaires dream (90-105). We'll have to wait and see.

    Last edited by Terry; 01-28-2011 at 04:58 PM.

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