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  • Viabilty and Vinegar

    Is it likely that a 50% vinegar, 50% water solution would deteriorate used flat panels, if flushed through panels for cleansing purpose?

  • #2
    What kind of vinegar are you talking about?

    There are 3 types:

    Culinary 3 to 5%
    Horticultural, 15 to 20%
    Industrial 30%

    If you live with hard water and your hot water pipes clog from deposits you use straight Horticultural to fill the pipes from your hot water tank over night. Culinary would be to expensive and to weak and things like sugar and salt added. I have no clue what it would do to Solar Thermal DHW. Perhaps CLR?

    MSEE, PE

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    • #3
      If you're referring to solar thermal panels as used for water heating, and attempting a form of chemical cleaning, probably not, but that's no guarantee. It depends on the collector material they're being flushed through, the temps. involved, the solution strength of the vinegar (stuff from the grocery store is usually ~ 4 %), and the flowrates used.

      Why vinegar ? If to remove suspected deposits in riser tubes headers, keep in mind that some of the more common chemicals in hard water are things like calcium phosphate and calcium sulfate. those two, and others to a lesser degree, exhibit something called inverse solubility. That means they come out of solution when warmed, precipitate, and stick to warmer surfaces (like collector tube walls). Unfortunately, those two salts are pretty much insoluble in acetic acid (vinegar).

      However, since the solubility is inverse to temp. , sometimes, as counterintuitive as it may seem, flushing a panel with COLD water will remove some of the fouling. Also, those salts are mildly soluble in hydrochloric (also called muriatic acid), or nitric acid. I'd avoid nitric acid however as nitrogen dioxide might form. That can be poisonous.

      More to the point, unless the collector risers are plugged or have "hot spots" from a form of dirt accumulation known as "deposition fouling" (not unlike sand accumulating on the inside of river bends) at places like riser/header joints, chemical cleaning is usually not required. Operating flow velocities and thus film heat transfer coefficients in most solar thermal panels are not high enough to have most fouling rates that can be accrued over time become significant to the point where performance is affected much. Anyway, if panels are fouled to the point of flowrates being very low and associated pressure drop being high, chemical cleaning probably won't get much of the original performance back.
      Last edited by J.P.M.; 05-03-2017, 05:27 PM. Reason: Added third paragraph.

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      • #4
        If someone had ran hard potable water through collector panels for many years. I would think the chance of deposit build-up would be the same as it is for coffee percolators. Running white vinegar through it once might help.
        4400w, Midnite Classic 150 charge-controller.

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        • #5
          Originally posted by organic farmer View Post
          If someone had ran hard potable water through collector panels for many years. I would think the chance of deposit build-up would be the same as it is for coffee percolators. Running white vinegar through it once might help.
          You would think so, and any deposits are often a combination of minerals, so it will probably take both types of rinse, one of which (a cold water flush) probably happens every time the pot is rinse/filled. I'd guess deposits on percolators of regular (non inverse) solubility salts usually form as/after the heating surfaces cool down. Most of the stuff with inverse solubility that sticks to heated surfaces when they are in operation (that is, hot) will get deposited during heating and get removed w/cold water rinsing. The stuff w/regular solubility will be more readily removed with vinegar or other acids. It'll probably take both methods for a coffee pot. I'd guess that regular cold water rinsing on a coffee pot takes care of most of the regular (non inverse) solubility deposits.

          There's also a lot of other stuff in coffee that will get cooked onto heating surfaces of a pot that vinegar will remove that's not present in a solar collector.

          In the old days, when boilers were blown down (flushed/cleaned), particularly when working fluid treatment was not as sophisticated as it has become, an often final step in a full drain/refill was often a cold water rinse for retrograde salts.

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          • #6
            Thanks for the help. White Vinegar with cold water, which becomes not too cold after entering covered panels. Mostly to clean dirt from being open to rural environment.

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            • #7
              Originally posted by J.P.M. View Post

              You would think so, and any deposits are often a combination of minerals, so it will probably take both types of rinse, one of which (a cold water flush) probably happens every time the pot is rinse/filled. I'd guess deposits on percolators of regular (non inverse) solubility salts usually form as/after the heating surfaces cool down. Most of the stuff with inverse solubility that sticks to heated surfaces when they are in operation (that is, hot) will get deposited during heating and get removed w/cold water rinsing. The stuff w/regular solubility will be more readily removed with vinegar or other acids. It'll probably take both methods for a coffee pot. I'd guess that regular cold water rinsing on a coffee pot takes care of most of the regular (non inverse) solubility deposits.

              There's also a lot of other stuff in coffee that will get cooked onto heating surfaces of a pot that vinegar will remove that's not present in a solar collector.

              In the old days, when boilers were blown down (flushed/cleaned), particularly when working fluid treatment was not as sophisticated as it has become, an often final step in a full drain/refill was often a cold water rinse for retrograde salts.
              I have served on a few subs, they use de-Ionized water to try avoiding too much mineral deposits in the boilers.

              4400w, Midnite Classic 150 charge-controller.

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              • #8
                Originally posted by Sunking View Post
                What kind of vinegar are you talking about?

                There are 3 types:

                Culinary 3 to 5%
                Horticultural, 15 to 20%
                Industrial 30%

                If you live with hard water and your hot water pipes clog from deposits you use straight Horticultural to fill the pipes from your hot water tank over night. Culinary would be to expensive and to weak and things like sugar and salt added. I have no clue what it would do to Solar Thermal DHW. Perhaps CLR?
                Acetic acid won't do much to copper, but it also won't do much for stuff stuck to the inside walls of a solar thermal collector if the stuck stuff is there because of inverse solubility characteristics.

                I'd also not use CLR if copper or copper alloys are involved per mfg. recommendations and the MSDS.

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                • #9
                  Originally posted by organic farmer View Post

                  I have served on a few subs, they use de-Ionized water to try avoiding too much mineral deposits in the boilers.
                  Working fluids in land side boilers start w/ D.I. water and then it gets tweaked w/stuff that enhances the transport properties like viscosity, surface tension, etc,. with the idea of enhancing phase change (boiling and condensing) heat transfer coefficients as well as for other purposes such as corrosion inhibitors, some lubrication enhancement or other rheological considerations for pumps, valves and other things. It's about a separate science onto itself. I've been told that ship boilers treat their feedwater in similar ways. I've never designed a boiler for a ship, but I don't doubt that the USN is quite picky and specific about working fluids in their equipment, particularly submarines. >> 110% support from me on that.

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                  • #10
                    Our contractor used to use a circulating sulfamic acid based mix on HVAC coils, did wonders for removing scale from inside the coils. He hooked it up and let it circulate for awhile

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                    • #11
                      "Rydelyme" is much safer than acids, removes minerals and water tower mud. The only cleaner that I use.

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                      • #12
                        Originally posted by J.P.M. View Post

                        Acetic acid won't do much to copper, but it also won't do much for stuff stuck to the inside walls of a solar thermal collector if the stuck stuff is there because of inverse solubility characteristics.

                        I'd also not use CLR if copper or copper alloys are involved per mfg. recommendations and the MSDS.
                        Understood. In North TX we had very hard water and the hot water pipes would clog up in two years with lime scale deposits. Gets to the point your shower is like being peed on. I used horticultural vinegar to fix it. We would disconnect the Hot Water Output in the HW Tank, run a plastic pipe up in the attic connected to a 5 gallon Igloo Water Jug filled with vinegar. Them open each faucet to purge water out of the pipes and replace with vinegar. Let it sit over night, pull the screens and restrictors out of faucet, then flush with water. Worked great, repeat in two years. It sucked.

                        In Panama water is super soft rain water. Heck just a drop of soap is all you need. You save a ton of money on shampoo, bath, clothes, and dish soap. No fabric softener required. Does wonders on skin and hair tone when you quit showering with rocks. Kind of amazing if you have lived with hard water all your life. Makes you look 20 years younger. Most people think I am in my later 30's.
                        Last edited by Sunking; 05-04-2017, 10:15 AM.
                        MSEE, PE

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                        • #13
                          Originally posted by peakbagger View Post
                          Our contractor used to use a circulating sulfamic acid based mix on HVAC coils, did wonders for removing scale from inside the coils. He hooked it up and let it circulate for awhile
                          On the inside of the coils. What is the working fluid ?

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                          • #14
                            Originally posted by Sunking View Post
                            Understood. In North TX we had very hard water and the hot water pipes would clog up in two years with lime scale deposits. Gets to the point your shower is like being peed on. I used horticultural vinegar to fix it. We would disconnect the Hot Water Output in the HW Tank, run a plastic pipe up in the attic connected to a 5 gallon Igloo Water Jug filled with vinegar. Them open each faucet to purge water out of the pipes and replace with vinegar. Let it sit over night, pull the screens and restrictors out of faucet, then flush with water. Worked great, repeat in two years. It sucked.

                            In Panama water is super soft rain water. Heck just a drop of soap is all you need. You save a ton of money on shampoo, bath, clothes, and dish soap. No fabric softener required. Does wonders on skin and hair tone when you quit showering with rocks. Kind of amazing if you have lived with hard water all your life. Makes you look 20 years younger. Most people think I am in my later 30's.
                            Yea, I don't look a day over 90 myself, but I work at it.

                            The precipitation fouling on most hot water service lines carrying hard or untreated water is due to the pipe being colder than the fluid. If the water is otherwise clean and potable, the precipitate is most likely the regular solubility stuff and hence vinegar will probably be as good a cleaner as any.

                            The point I'm making on cleaning is that one way to consider the stuff that's usually in hard water is that it's made up of two different types of stuff. One type has regular solubility, that is, it's solubility in water increases with temp. The other type, which has a property called inverse solubility, decrease in solubility increased temp. That means that the first type will precipitate out of solution on to cold surfaces. The second type (and this is the counterintuitive part) will precipitate out of solution onto hot surfaces.

                            So, the type of stuff that will precipitate on to hot or cold surfaces, while probably similar, will be slightly different. one of those differences is usually what will dissolve or remove each type of material.

                            As for cleaning/dissolving the collected junk, because the two types are similar but not chemically identical, they are removed/put back into solution by different chemicals. The first type, the stuff with regular solubility and of the type that usually tends to collect on cold surfaces is usually soluble in vinegar.

                            The second type of material, the stuff with inverse solubility and of the type that usually collects on hot surfaces is mostly insoluble in vinegar.

                            So, to clean surfaces exposed to what's commonly considered hard water, for containing surfaces colder than the fluid, vinegar/acetic acid will probably be effective. For containing surfaces warmer than the fluid, vinegar will not be the best choice or may be ineffective. For that task, hydrochloric/muriatic acid may be a better choice, depending on the material of the containing surface. Always check for material compatibility.

                            Lastly, and to back up/agree with your point about soft water, although I don't much care what it may due to your looks (maybe some of the origin of the fountain of youth B./S.?), water chemistry and treatment is different all over the world. Some boilers, for example stay clean running on 1X through ground water. I once had a heat exchanger design that had a terrible galvanic corrosion problem. Turns out the zinc anodes in the design that were usually fine for most applications were unsuitable (not high enough on the galvanic chart), but it took some time to figure out the problem was because of the water chemistry at the job site - from Lake Titicaca in Peru. It was such that it ate zinc anodes, quickly removing any galvanic protection. We changed them to magnesium and things improved. Also found a few electrically unbridged flanges and some poorly grounded equipment that contributed to the galvanic corrosion. Long, boring story, but most of the vessel corrosion was from the water chemistry.

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                            • #15
                              You can get food grade citric acid from Duda diesel. Back in the day used to clean water mains with NSF hydrochloric acid at 535 gallons per minute through isolated fire hydrants. For jobs a little less demanding like fire sprinkler piping and ships pipes we went with citric acid. Worked quite well.

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