(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 15 of 40

Thread: 120F not hot enough?

Hybrid View

  1. #1
    DIY Junior Member HoracioO's Avatar
    Join Date
    May 2009
    Location
    NV
    Posts
    26

    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
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,401

    Default

    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
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    DIY Senior Member Runs with bison's Avatar
    Join Date
    Aug 2009
    Location
    Midwest
    Posts
    892

    Default

    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????

  4. #4
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
    Join Date
    Jun 2009
    Location
    Penticton, BC
    Posts
    810

    Default

    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
    Join Date
    May 2009
    Location
    NV
    Posts
    26

    Default

    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...

  6. #6
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    Location
    San Diego
    Posts
    9,001

    Default

    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
    Join Date
    Aug 2009
    Location
    Midwest
    Posts
    892

    Default

    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
    Join Date
    May 2009
    Location
    NV
    Posts
    26

    Default

    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.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •