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Distilled Water

Perfectly distilled water is H2O with nothing else in it. This is only a theoretical possibility as things will start dissolving into the water as soon as it touches anything. Things like glass have very low solubility, things like table salt have high solubility and metals are somewhere in the middle. For reagent quality distilled water, there is no metal on the condensation side of the system for just this reason.

In a cooling tower situation, distilled water would be a disaster. The continuous flow of distilled water through the pipes would dissolve the metal in the pipes. When I was growing up, there was a power plant built about 100 miles away. The fired up the system and within 2 weeks the cooling tower piping was riddled with holes. Analysis showed that the water was too soft and dissolved the pipes from the inside out. The metal as fine particles went up in the steam from the cooling tower. All new piping and rehab on the turbines later, they watched the water more closely. Now this was the worst case, hot water at high flow rates with significant makeup water rate. But this was also not distilled water, just very soft water.

In a residential steam boiler, you are not talking about the same kind of situation, but you will be taking a chance. The question comes down to how much make-up water is being added and whether the metal has an exit path like the cooling tower. If there is a significant yes to both questions, then you are at risk of eating up the metal in the system.

Also, distilled water is expensive and it would be hard to do an automatic feed. I would just go with an ion exchange setup that exchanges the calcium and other harmful minerals for benign ones. This way there is little risk to the metal in the system, since there are loads of ions already in the water. You can put this in line on the automatic feed and you're done.



  • Foreman
    Foreman Member Posts: 30

    I have steam heat, I have well water, is it a good idea to use distilled water? Seems to me its used in automotive radaitors, so why not boilers?

  • Timco
    Timco Member Posts: 3,040

    I think the water loses it's steam molecules in the distilling process, and will not steam when heated....just a guess.

    Just a guy running some pipes.
  • Constantin
    Constantin Member Posts: 3,796
    Distilled water is great...

    ... it would solve most scale problems found in hydronic heating systems. That said, are scale problems great in steam systems?

    Besides the boiler and some near-boiler piping, I doubt one would find a lot of scale in them. After all, if the system is producing dry steam, then the water is getting just as vaporized as the distilled water is in a still. However, if the water is hard, then the boiler will lose efficiency over time because its HX will become caked with junk as make-up water is introduced. Water treatments like those offered by George at Rhomar are definitely warranted.

    The other issues associated with hydronic systems, like rust, mud, etc. are not going to change, because they're primarily associated with the chemistry of water, not the solids initially dissolved in it. An inhibtor could help here. Plus, refilling with distilled water could get pricey.

    A closed-loop hydronic system on the other hand is a prime candidate for distilled water in areas with problematic water sources (Chlorine, sediment, etc.) An inhibitor for the water is a good investment, particularly if you have a sensitive heat exchanger. A separate water feeder can then keep the system happy by feeding it treated water, not the stuff from the Well or the city.

    However, one could also make the argument that if the system has been purged successfully, then perhaps its even better not to fit a water-feeder at all. Any eventual holes should be addressed by fixing them, not feeding more make-up water. I bought the system cleaner and inhibitor from George even though my contractor had never heard of it. I consider it a good insurance policy.
  • George_10
    George_10 Member Posts: 580
    Steam systems are very susceptable to scale

    for two reasons. Minerals in the water come out of solution an plate out on metal surfaces, i.e. the HX.

    Also since new water is being added after blow downs, there is a greater possibility of more scale forming. Very hard water is a real curse to these systems.

    Steam treatment can reduce scale buildup and also protect the metals from corrosion. The other problem with adding new water is you are also adding more oxygen.

    Distilled water in closed loop systems is not a bad idea as long as it is treated. Distilled water left alone is very agressive to the metals in the system.

    The bottom line answer to both situations is clean and treat the heating system and prevent these problems before they can start. Mechanical breakdowns can not be prevented.
    Water related chemical problems are preventable. In the industrial world this is common practice, unlike the home owner world. If this did not make economic sense, the comptrollers of these outfits would put a stop to preventative maintenance. The reason they continue the practice is simple. They have fewer breakdowns and also lower fuel bills. These savings go right to the bottom line.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    Water chemistry is a very complex subject, but here's some culls from the web.

    "dissolved oxygen in pure water is five to ten times more aggressive than carbonic acid"

    "If you are talking pipes and storage containers, RDD water could be considered more 'aggressive' than water containing dissolved substances. Water without anything in it will tend to dissolve anything it comes in contact with (the copper or iron in a pipe, the lead from a solder joint or brass fixture, etc.) more 'aggressively' than water that already contains some dissolved substances. Also, one of the 'things' easily dissolved by RDD water is carbon dioxide. This forms a weak acidic solution (carbonic acid) which can cause further dissolving and corrosion of materials that it comes in contact with - that's how caves get formed - soft, acidic rain water dissolves limestone (calcium carbonate) becoming hard water in the process of forming the cave structure. Even soft water with naturally low levels of calcium and magnesium ions (including softened water where the calcium and magnesium ions are replaced by sodium or potassium ions) seems to be more 'aggressive' at picking up contaminants from pipes than hard water."

    "both distilled and de-ionized (DI) water have a very low dissolved solids content. This means there is a very low concentration of ions in solution, as indicated by high conductivity. It takes a lot of effort and energy (various purification processes) to remove the majority of ions from water. Water desires these ions back to maintain equilibrium and will aggressively take them from any available source"

    "Ultrapure water has a very low conductivity and is a very aggressive solvent which will attack stainless steels and even glass. Really pure water is actually difficult to work with and store--it readily absorbs gasses and requires Teflon coated containers under inert gases."


    I don't believe it's a good idea to use distilled water in a hydronic system. If I remember my chemistry lectures and experiments properly, they don't call water the "universal solvent" for nothing! If the water source is exceptionally hard, distilled water with intentionally added minerals would seem appropriate.
  • Mitch_4
    Mitch_4 Member Posts: 955
    say what??

    > I think the water loses it's steam molecules in

    > the distilling process, and will not steam when

    > heated....just a guess.


    > T

    there is no such thing as "steam molecules" in water. Steam is water heated to 212° F + 970 btu's of latent heat.

    Distilled water is regular water that is boiled, and the steam recondensed in a sanitized stainless steel condenser. Because steam holds no impurities found in the original water (they do not change state when the water does) the steam contains pure water. In fact pure distilled water will not even conduct electricity (try it with a flashlight bulb and a battery)

    Not being mean, but this is basic science, and that was a VERY poor guess..

  • Dirk Wright
    Dirk Wright Member Posts: 142
    Treat the well water

    I would treat the well water with filtering and other methods before adding it to a hydronic system. This means having your well water tested for hardness, biologicals, pH, etc. Then I would figure out what the industrial folks do who use hydronic heat and do something similar. As others have said DI and distilled water are aggressive, as well as extra O2 in the water. Also, I would not assume that a normal water softener would be a good idea either since the added sodium may be corrosive. I don't have an answer for you, but hopefully this is somewhat helpful.
  • Weezbo
    Weezbo Member Posts: 6,232
    get the water to a test outfit...

    filtration might be all that would be required. or adding a known water supply. distillation basically turns out heavier elements that cannot travel "with" during the process.

    down in Kentucky the distillers used to turn out the revenuers...so i suppose the revenuers were too heavy to go with:) dont quote me on that ...i been wrong ...wrong wrong wrong wrong wrong :) i think that a steam boiler Basically acts like a still ,you refine the heat out of the fluid during transformation of state:) thats like when the revenuers had to shake a leg and chase down the moon shiners who blazed out of the hills on their way north to chicago...at least Thats how i understand it*~~/:)

    any distilled water would ruin the heat they were looking for plus you cant really add water to the gas tank in a pinch:)
    Its basic physics..i think physics is something the people up in chicago used to add to moonshine to aid in the redistribution of heat...

    i dont know if this is true buh i heard it helps people dance faster.putting distilled water in it just makes people angry... so, i guess the moral of the story is if you dont want to make people angry dont use the boiler as a still:) unless of course you like,live in kentucky *~/:)

    oh and look out for the fat revenuers they have some pretty fast cars:)
  • thfurnitureguy_4
    thfurnitureguy_4 Member Posts: 398

    isn't what is filling the steam pipes distilled water once it condences?
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,250
    When the book...

    ..."Life According to Weezbo" comes out, I'm buying a copy! Hope somebody is saving Weezbos posts. Henry Miller, watch out.

    Yours, Larry
  • Drew_2
    Drew_2 Member Posts: 158
    Myths about Deionized/Distilled Water

    Deionized Water Myths

    Distilled water involves some form of evaporation process from the feed water with subsequent condensation of that water vapor. The typical process is to heat the water to make steam (sometimes with a negative pressure assist) and then cool the vapor stream at some remote place to make distilled water. Deionized water is water, which has been passed through a bed of resin beads, which have selective anodic and cathodic sites chemically bonded to them--in effect; the ions from the dissolved and disassociated minerals are attracted to the ionic sites on the beads. The treated water will have less ionic load after the minerals are removed from the feed stream.
    Distilled water, depending on the feedstock and the process involved, usually has a fair amount of dissolved gasses and also contains some of the volatile components from the feed water (such as volatile organic components). To make ultra pure water, distilled water is often degassed and then treated with deionizing resins. The rationale behind this is the deionizing resins are fairly expensive and do not have a large capacity to extract ions, so using distilled water as a feedstock greatly prolongs the life of the resin beds. After distillation, deionization and degassing, the water can be considered ultra pure. In some applications, and if the feed water is very clean, that is, has a very low ionic component load, then reverse osmosis can sometimes be used to remove some of the minerals before deionization instead of distillation. Reverse osmosis is fundamentally a hyper filtration process whereby molecules are filtered out to some extent. [I know, this is an oversimplification, but this is a mixed audience.] There is a fair amount of operation involved in reverse osmosis and depending on the quality of the feed water, chemical flocculation or preconditioning of the water is mandated. I should point out that regardless of treatment, softening of the water is usually a first step to prevent scaling of the treatment system.
    Ultra pure water has a very low conductivity and is a very aggressive solvent, which will attack stainless steels and even glass. Really pure water is actually difficult to work with and store--it readily absorbs gasses and requires Teflon coated containers under inert gases.
    For critical cooling applications you are basically looking to prevent scale formation on heated or cooled surfaces. The typical scale components of "hard" water are magnesium and calcium carbonates; these compounds have a narrow band of solubility in water as dependent on temperature--if the temperature is heated above 90C or cooled below 2C the carbonates tend to precipitate out of the water and deposit on your expensive equipment as a scale deposit. Scale reduces the coolant flow and disrupts the transfer of heat in the system, both undesirable and potentially damaging conditions. Distilled water is probably sufficient for your application and is much less expensive than deionized water. Also, the dissolved gasses and small amount of ionic load inherent in distilled water will help to protect your metal contact surfaces from corrosion by the water.
    If, for some reason, the distilled water is eating your equipment (watch the welds!), you may have to go to another coolant fluid, perhaps a chlorinated or fluorinated hydrocarbon. Tin-plating the water contact surfaces is also a very effective means of protecting components from corrosion by water, and tin and tin oxides are very insoluble in water. However, since your equipment was designed to be water cooled, I suspect distilled water will meet your needs.
    Dale Woika
    Surface Conversion Sciences - Bellefonte, PA, USA
  • Foreman
    Foreman Member Posts: 30

    Wow! Thanks for everyones input, I learned a lot, I think! :)
  • Caselli
    Caselli Member Posts: 40

    Moonshiners ? Chicago ?!

    According to Robert Mitchum it was "...Sometimes into Ashville, sometimes Memphis town." :-)
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