Crud forming in demand water heater

Bigwooo
Bigwooo Solar Expert Posts: 62 ✭✭
We are planning to incorporate a solar water heating system in an off grid home we’re building in Mexico. Before I install it however, I’d like to see if anyone can help solve a problem my neighbors are having with their water heaters so I don’t have the same issues with my solar water heating.

They are having problems with minerals collecting in their water heaters. These minerals are brown in color and are only found in the very hot tubes of the on- demand water heaters, or are found collecting at the bottom of tank heaters. They bond to the pipes of the on demand heaters decreasing flow then break off causing problems with clogging in the toilets and faucets, or the stuff slowly collects and fills the bottom of tank water heaters.

Talking with my neighbors we have two theories:

1. The water is very hard and some minerals are becoming solids when heated?

2. Maybe a ground issue? We have no domestic water supply. The water is pumped from an underground cistern to the house. The underground supply line is 1 ½” PVC, but the house plumbing is either ½” or ¾” copper. The houses are not grounded to the copper pipes; everything is grounded through a ground buss to a ground rod(s). Since the copper pipes are not grounded, could there be some kind of electrolysis causing the brown crud to form?

My questions are:

1. Has anyone experienced this?
2. Do the copper pipes need to be connected to the ground buss and could that be the problem? Some sort of electrolysis?
3. Would some sort of water filter system be the key to solving the problem? If so what mfgr/system would you suggest that would both provide potable drinking water and filter out minerals while producing no waste water (maybe a tall order). If I'm going to spend the $$ on a whole house filter system I'd like it to also purify the water so it's drinkable.
4. Any other ideas on what may be causing the crud?

Any suggestions would be appreciated. I don’t want to spend the $$ on a solar water heating system to only have it rendered useless in a couple years by this brown mystery crud.

Comments

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Crud forming in demand water heater

    What works for me: Magnets ( Magnetic Water Conditioning )

    I used banks of magnets, aligned and zip-tied to the pipes. Then the "crud" is soft and crumbly. I flush my 2, 50gl nat gas tanks every 9 months or so (I installed a ball valve on the drain when new, not the hose bib). I get about a pint of marble sized agglomerations of deposits from each tank. One is 20yr old, other 18 yr.

    I purchased the magnets and booklet from orgonelab.org for about $35.
    Cheap insurance I figured. You can spent $500 for fancy magnetic systems. I chose the cheap method.
    2 sets magnets, & book did my 2400sq ft house
    Cold water from street, inlet to water heater1, inlet to water heater2, feed to sinks, shower, washing machine.
    Took a couple of hours & 20 magnets.
    http://www.orgonelab.org/cart/ymagnets.htm
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Crud forming in demand water heater

    I don't know about magnets,, sounds sorta like the magnets on your cars fuel line...
    The problem is minerals precipitating out of the water as it is heater. There are water softener solutions out there. I would consult with a hydronic heating expert, who has experience with hard water.

    I have seen a pre-filter that supposedly helps keep the preciptates out of the water heater, but I can't vouch for it. :http://cgi.ebay.com/Rinnai-Cuno-Aqua-Pure-Hot-Water-Heater-Scale-Inhibitor_W0QQitemZ270337358849QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item270337358849&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A0%7C293%3A2%7C294%3A50


    Or google Aqua-pure

    Tony
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Crud forming in demand water heater

    bigwoo,
    i have a utility supply of water and i sometimes get what you have described at the bottom of my 40 gallon natural gas water heater. i have occasionally seen my hot supply come out dirty looking and i rarely seen this through the cold supply. i believe this is due to the old water pipes under the streets that break through hot/cold seasons and age which allows the minerals to get into the pipes. it accumulates at the bottom of my hot water tank making it more pronounced than it is, at least for me. i have been contemplating a filter for mine, but i don't savor the idea of changing out these expensive filters as often as would be needed so i would imagine your circumstance is even worse as you have more to lose and a larger supply of minerals in your water. i believe some type of filtering would be mandatory for you, but magnets sounds a bit like hocus pocus. i am in the same boat and have not addressed my problem as of yet so i'd be interesting too as to some filtering options and what it is you windup doing about it. have your neighbors any filters?
    as to grounding the water pipes, that is standard to be done here in the states, but not for water purity problems.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Crud forming in demand water heater

    Sounds like you are getting dissolved iron into your water heating system...

    Either that is coming from your well/water source, or it is forming in any iron components in your water system.

    Here is a state website that discusses the basics of the "iron" problem. Depending on what type of problem you have, there may be several methods to fix it.

    Another possible source of iron is galvanized piping or the tanked hot water system.

    Generally, the copper pipes are all bonded together (with copper wire and bonding clamps--hot and cold), and a ground rod... The hot water tank is isolated using insulated union to prevent galvanic corrosion. Also, inside the tanked water heater is a sacrificial anode to help prevent rust forming. Usually, the last some 3-12 years, then the tank will rust out after the anode has been eaten up. You can replace them every few years and get a longer life on your tanked water heater... Not sure a demand hot water has the anode (or even if it needs one as there is generally no steel tank/parts in the water path).

    Other issues involve the water chemistry and the type of anode--and can create "rotten egg" smelling water. Changing to a different type of anode can help.

    Or, you can have a "too cold" water heater (below ~120F) and get a black high temperature bacteria that grows inside the water heater...

    The last several issues do not sound like your problem.

    The Wisconsin Iron Problems website will probably get you started. I like the idea of aerating the cistern and to convert the soluble iron to insoluble iron, then you can filter it out. But--without testing your water, you will not know what your specific issue is.

    If you have a mix of galvanized and copper piping (you don't?), there are lots of recommendations out there... Usually using a 6-12 inch brass pipe to convert from copper to steel/iron pipe. Or use a dielectric (insulating) fitting. Again--probably not your problem (unless you are using a metal tanked hot water heater).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Crud forming in demand water heater

    As I said,, consult with a good water quality guy. (Not just your local Culligan salesman!0 While it could be dissolved iron, it is also likely to be dissolved calcium carbonate or dissolved salts, or tons of other different minerals.

    When you evaporate water, the concentrations of dissolved solids (hard water) increase and precipitate out. Look in the bottom of any tea kettle, or the water course of a coffee brewer. The white deposit left behind was once in the water.

    These minerals DO NOT generally come from the piping, although that can happen. Somewhere on this site is a discussion of this problem is hot water systems,, but I can't find it on short notice.

    T

    PS. I have been told that Florida water is very prone to dissolved solids

    All this not withstanding good plumbing practices with dielectric fittings etc.
  • Bigwooo
    Bigwooo Solar Expert Posts: 62 ✭✭
    Re: Crud forming in demand water heater

    Neil,

    Our water is pumped from a fairly shallow well, brought by truck and stored in an underground cement cistern (10,000 gallons). Our neighbors are closer to town and are on the municipal system, but the source of the water is the same. We haven't been using ours long enough yet to see if we get the same problem.

    We are filtered... somewhat. We have a Dankoff pump and a debris filter that comes with it between the pump and the tank. I'm sure the filter does nothing for dissolved minerals though.

    One of my neighbors may be installing a water softener, It will be interesting to see if that resolves the problem.

    When (if) we do come up with and answer I'll post it here.
  • Bigwooo
    Bigwooo Solar Expert Posts: 62 ✭✭
    Re: Crud forming in demand water heater

    BB thank you for the links...I have lots of reading to do.

    Icarus we may have to resort to testing the water, but it will have to be brought back from Mexico to the states to get the testing done. Quite a pain, but may be the best solution.

    Mike I may resort to magnets but I'd like to resolve the problem first if I can.

    Thanks for your suggestions.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Crud forming in demand water heater

    Find a hot tub/pool supplier. Get a package of water test strips that include a Calcium/hardness test strip:http://www.amazon.com/AquaChek-Bromine-Balance-Alkalinity-Hardness/dp/B000FOH752

    This might give you a preliminary indication as to whether you are on the right track.

    Tony
  • Ecnerwal
    Ecnerwal Solar Expert Posts: 101 ✭✭
    Re: Crud forming in demand water heater

    You have hard water - probably hard water with some iron. An inexpensive set of test strips will clarify that and provide some numbers. Not as precise as a $100 lab test, but enough to tell you what you are dealing with, and how much softener you need.

    Problem being that water softeners use/waste water, so if you're having it trucked in, that might go a bit expensive. Fairly simple, though, and depending on what you have and what you care about you can just soften the water going into the hot water heater. With a little system planning you can collect the waste water from the softener (or an RO unit) and use that (stored separately) to flush toilets with (assuming flush toilets).

    I don't think the magnets do anything but move money from you to the people selling magnets, but I'm one of those "hard fact engineering" types - perhaps they work if you believe in the mystical mumbo jumbo that makes no sense if you actually know what an ion is... Free to try if you collect a few dead hard drives and take them apart...

    http://www.chem1.com/CQ/magscams.html

    Or just fill the water heater with acid (vinegar, citric, phosphoric)once in a while to descale it.
  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    Re: Crud forming in demand water heater

    Magnetic water treatment - and almost any other magnet treatment for anything is pretty much all a myth.

    Good article on it here http://www.csicop.org/si/9801/powell.html

    A few other interesting articles there also.
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Crud forming in demand water heater
    Ecnerwal wrote: »
    I don't think the magnets do anything but move money from you to the people selling magnets, but I'm one of those "hard fact engineering" types - perhaps they work if you believe in the mystical mumbo jumbo that makes no sense if you actually know what an ion is... Free to try if you collect a few dead hard drives and take them apart...

    http://www.chem1.com/CQ/magscams.html

    Well, even they say it can't hurt, and sometimes seems to work.

    When you are off grid, and truck in water, you can't waste water with a salt cycle softener or a RO unit, each dumps about 5 gal for each gal of treated water produced.
    For a single water heater, $25 is hard to go wrong, and it might work.
    South West, the problem is most likely dissolved calcium - which a water softener would cure.
    There are ion exchange tanks (same resin -zeolite) used in a stand-alone water softener, but the tanks are recharged at the plant. Maybe dragging one down for the season is an alternative. We had softener service at our house when I was growing up, they changed the tank about every 2 weeks, for a household of 4, so maybe 1 tank would last a season for hot water only.

    Try the test kit, and see what the problem is.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
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    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Bigwooo
    Bigwooo Solar Expert Posts: 62 ✭✭
    Re: Crud forming in demand water heater

    Thanks for the test strip links, we'll give those a try and see if we can isolate the problem some...and yes we do have flush toilets ;). I'm going to help my neighbor and use him as the guinea pig as he is having problems right now. We won't be living there full time until later in the year. Hopefully he's worked out the kinks by the time we're ready to install our solar water heating. They are looking into water softening, but they have town water, we don't.

    We are researching some newer RO systems that don't waste as much water. We'd really like to RO the entire house so we can drink out of the faucets in the bathroom/kitchen etc. and not have to worry about it. Our water is clean and straight out of a well, but the truck that brings it leaves little to be desired. The RO waste water could be put to use for flushing toilets....but that involves another pump/tank etc. I'm not sure if I want to get that complicated.

    More to follow...
  • LucMan
    LucMan Solar Expert Posts: 223 ✭✭✭
    Re: Crud forming in demand water heater

    Here in NY the plumbing supply houses will test your water for minerals for a small fee.
    A water softener will help keep certain mineral deposits in check, but it won't help much with iron , they waste lots of water and you will get tired of buying expensive salt.
    Most likely your deposits are manganese and calcium carb. but only a test will tell.
    My solution would be to install a set of valves on your water heater with some hose connections for flushing periodically. You will need a small circulation pump and this http://www.rydlyme.com/home.html. . This product is completely safe for use on copper.
    Avoid acids as they will eventually eat away the copper coils in the heater.
  • Bob McGovern
    Bob McGovern Solar Expert Posts: 25
    Re: Crud forming in demand water heater

    Um... Rydlyme IS acid ("hydrogen chloride" -- pH <3 according to the MSDS.;)) Acids are fine, as long as they are suitably dilute and not used too often. Our ground water is very hard, extremely hard, and we flush out our Bosch demand heater every two years with plain white vinegar and a small utility pump. We have two inlets (one is the pressure relief valve, which also benefits from de-scaling) and valves to isolate the water heater. You'll need to shut off the gas supply and make sure your pump is running the correct direction. After about 30 minutes, the vinegar runs clear. HINT: Warm the vinegar before starting for extra-good scale-busting action!