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Cleaning a Tankless Water Heater

Discussion in 'Dumaguete City' started by Edward K, Jan 8, 2017.

  1. Edward K

    Edward K DI Member Veteran Navy ✤Forum Sponsor✤

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    I ran across a post somewhere else that talked about how to clean "or descale" a tankless water heater, which i've never had until here. Recommended running vinegar thru the system.

    Do you clean your Tankless Water Heater ?? How often ?? What do you use ?? Any net info you recommend ??
     
  2. Dave_Hounddriver

    Dave_Hounddriver DI Forum Patron Highly Rated Poster Showcase Reviewer

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    I clean my "on-demand" hot water heater on rare occasions due to potential mold or bacteria build up. Since that is what I am trying to kill, I use bleach. The first time I tried it I got bleach all over the place so I am very careful now. I simply disconnect the water supply line and raise it high so I can fill it with bleach and have it gravity feed through the system. When flushed well I find it kills all the green algae that grows around the heater over time. I would not have bothered except for getting bacterial infections on my skin that I could not explain. Cleaning the water heater was part of an overall cleaning to get rid of mold etc. so I cannot be absolutely sure it was needed but I am absolutely sure it did not hurt.
     
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  3. Wrye83

    Wrye83 DI Forum Luminary Admin Secured Account Highly Rated Poster SC Connoisseur Veteran Army

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    I kept getting skin infections (almost like an abscess) in my armpit and a few others who have used my shower have as well. Makes me wonder if there is something nasty growing in my water heater. I always thought the extreme heat would take care of it but now that I think about it....I never took a shower with the thing on the highest setting. :cautious:
     
  4. Dave_Hounddriver

    Dave_Hounddriver DI Forum Patron Highly Rated Poster Showcase Reviewer

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    If you use bleach to clean your water heater, be careful because it is a strong electrolyte. That means even if your water heater is unplugged, if you have metal hoses and you are hanging on to the them when you fill the lines with bleach you may get a static shock. Happened to me until I realized rubber gloves are wise when handling pure bleach.
     
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    Edward K

    Edward K DI Member Veteran Navy ✤Forum Sponsor✤

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    Using this old post for an update.. Checked out some youtubes on cleaning a tankless water heater, both recommended vinegar and a small recirc pump. With our new pressure system (fantastic), the old wtr heater is still running weaker than the new ones, so this is my next step. DOES ANYONE HAVE A "CLEANING KIT" (5 gal bucket, small pump (fish pond?), and hoses they would loan me (will contribute to your cost)).. Or know where i can rent one ???
     
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    Edward K

    Edward K DI Member Veteran Navy ✤Forum Sponsor✤

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    My old Water Heater is running very slow, much more so than the other two newer ones in the house. I'd like to try to clean out the hard water scale by running vinegar through it but i can't find anyone with a bucket/ pump/ hoses set up who will post the existence here or agree to loan it (i'd give a deposit so i'll return it in working condition)...... Maybe it's easier to throw it out and get a new one, it's been installed for many years and i doubt it's ever been "descaled". If it's not a scale problem, then it needs replacement anyway... ?????????..
     
  7. Show Pony

    Show Pony DI Senior Member Highly Rated Poster Showcase Reviewer

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    @Edward K
    Couldn't you just fill the heater with vinegar and let it sit for a few hours (days)?
    If the heater is very large you could dilute Muriatic acid and use that (it's cheap).
    Before using muriatic acid you should get some advise from someone with a chemistry background. There is probably someone around here that would know a suitable concentration.
     
  8. Wrye83

    Wrye83 DI Forum Luminary Admin Secured Account Highly Rated Poster SC Connoisseur Veteran Army

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    That depends on what the inside of the water heater is made out of. Is it copper? Stainless steel? Since muriatic acid (aka hydrochloric acid/HCI) will eat away different metals at different rates the time to leave it in there will vary. It seems @Edward K is willing to toss the heater so personally I would so f*ck it and go with 20% HCI and let it sit in there for 4-6 hours. After that I would dilute some baking soda and carefully - that sh*t coming out is going to be toxic - flush the heater to neutralize the acid and then give another 3-4 flushes with water.

    I'm no chemist so if this ruins your heater don't come looking for me. :wink:
     
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  9. Dave_Hounddriver

    Dave_Hounddriver DI Forum Patron Highly Rated Poster Showcase Reviewer

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    My ex used Muriatic acid on the sink faucet. It started the faucet rusting and, even though she only did it the one time, it got worse and worse until we had to replace it within the year. It was not the faucet as we have an identical one on the CR sink downstairs and no problem with rust.

    I would not use it. What you need is CLR. Sometimes you can find it, or a generic version of it, at the American Import store in Daro, across from the organic market. But it is seldom there so you may have to ask them to text you when they get some. Also, the stuff they get is a very weak solution so you would have to leave it sit in there for a few days to do any good. But at least its not toxic like Muriatic.
     
  10. Wrye83

    Wrye83 DI Forum Luminary Admin Secured Account Highly Rated Poster SC Connoisseur Veteran Army

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    If your sink has a trap that acid could have sat in there for quite some time, even if you rinsed it out. Once the acid eats away the top protective layer of the metal (if it has one) the water will start doing what it does to metal. If you throw an acid down your metal drain (CLP also has acids - lactic and gluconic - and oxidizers...probably not good for anything already rusting) you are going to have the neutralize it with a base (baking soda) or it will start pitting and rusting.

    The problem is that scaling/calcium is not going to be evenly distributed in pipes. While the acids eat away at the calcium buildups it will also be eating away at exposed metal.
     

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