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cleaning plate exchanger

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by nealj, Oct 1, 2009.

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  1. nealj

    nealj Member

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    Just fired up the owb first time this fall. It seems like my plate exchanger isn't taking as much heat off the owb water as it could. Has anyone done anything to clean one of these? It has been in service for 4 years Thanks for any replies.

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  2. heaterman

    heaterman Minister of Fire

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    When we install one we put ball valves on the in/out lines of the HX. Inbetween the BV's and the HX we tee in a boiler drain. Set up this way, you can easily connect a pump and run a solution of boiler cleaner or mild muratic acid through the HX until clean. I've seen a lot of them plugged solid though and once you get to that point there's not a lot you can do but replace it. If you can't circulate the cleaning solution through all the sections it's pretty much toast.
  3. jebatty

    jebatty Minister of Fire

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    A good practice with a plate hx is to install a hot water filter in the supply line. The instructions with the plate hx likely tell what size filter to use, but something from memory tells me 50 micron is adequate. On a first install, you might be surprised by the gunk it picks up, and gradually over time less and less, so frequent checking and changing as needed is important.
  4. in hot water

    in hot water New Member

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    It doesn't take much scale to really start hampering the HX in those exchangers. Hard water and high temperatures are a problem for any HX surface. I like to install heat exchangers with these Webstone flush valves. It allows you to run a coil cleaner solution with a small pump to clean them out without removing or draining the system.

    I have one customer that removes his and takes it to a radiator repair shop and has it "cooked" out.

    hr

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  5. dogwood

    dogwood Minister of Fire

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    HR, or any else who might know. I managed to find the Webstone (4061 Series) flush valves in the above picture. I will use them to periodically flush my DHW flat plate as you suggest, since our DHW is hard. I have purchased a small Laing recirculation pump (SM303BTW) which will normally circulate the DHW through the flat plate when called for. My questions are these. Since I would need a small pump to circulate the coil cleaning fluid through the flat plate could I place the flush valve in front of the Laing pump which is ahead of the flat plate, and utilize the Laing to circulate the cleaning solution periodically. Do you think the solution would damage the pump in any appreciable way. It would certainly be a simple way to go. Also another thread suggested using a vinegar solution as opposed to coil cleaning solution to clean out the hard water deposits. Do you think there would be any appreciable difference in their effectiveness, or possible problems, if either is running through the Laing pump. Also, is coil cleaning solution readily available, or would anyone know where I would locate some. Excellent suggestion to use these valves. Thanks.

    Mike
  6. jebatty

    jebatty Minister of Fire

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    I'm shooting from the hip, but I doubt vinegar would harm the pump, as its concentration is very low and it is a weak acid. What I have read regarding a plate hx is to use muriatic acid, aka hydrochloric acid, which is a strong acid. I don't know the concentration recommended though. Whether muriatic acid would harm the pump is way beyond my knowledge.
  7. dogwood

    dogwood Minister of Fire

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    Thanks Jim. I have used muriatic acid to clean bricks. It would probably would make short work of any deposits in the flatplate if I worked out another way to circulate it through. I'd be a bit worried to about letting muriatic acid run through the Laing pump, seeing how it eats cement residue. I've never seen or heard of the coil cleaning fluid HR mentioned above. I wonder how strong this might be? Anyone else have any thoughts or experience along these lines about cleaning solutions I can safely circulate through that pump and flat plate both to have an easy clean out method for the hard water deposits? Your thoughts would be appreciated. As you suggest Jim, the vinegar approach may be way to go. I'll have to find that previous post about cleaning flat plates that way. Maybe contact Laing too.

    I wonder what the "cooking out" method of cleaning a flat plat at the radiator shop HR mentions entails? Any automotively inclined folks out there know? Maybe that is something one could replicate. Looks like I should make the flat plate easily removable either way, maybe with flanges or unions.

    Mike
  8. DaveBP

    DaveBP Minister of Fire

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    I've used vinegar to remove hard water deposits. White vinegar is pretty cheap at the grocery store by the gallon jug in the canning and pickling dept. Works faster if it is hot.
  9. dogwood

    dogwood Minister of Fire

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    Thanks DaveBP. If you had to venture a guess, how long would you run heated vinegar through a flat plate to clean it, and how often would anyone think it should be done on a preventative basis. Do hard water deposits come right off or does it take soaking a while. I'm just looking for a ballpark figure. For example should I run the vinegar through the flat plate every three months for an hour, or is that way to often or too long? Its a dumb question, but one I need to figure out. My flat plate is brand new right out of the box. I want to keep it in good shape. Our water is hard but goes through the water softener before getting into the DHW tank. The hardness setting is at 20 on the water softener if that means anyhing. I read here that even serious calcification can be soaked away, so getting off on the right foot should prevent this eventuality, providing I clean it often and long enough, whatever that entails. I bet someone out there has dealt with this and could provide some pointers.

    Still looking for input on how harsh coil cleaning fluid might be on the Laing circulator too if I circulated that when cleaning instead of vinegar. Thanks for the help. I can see why Gooserider recommends sidearms rather than flat plates to avoid just these type problems.

    Mike
  10. DaveBP

    DaveBP Minister of Fire

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    What you get for deposits will differ from one location to another. Must be some local authority you could ask about your water chemistry that could tell you what might me gumming things up. If it's just calcium compounds you might be able to use the milder acids like vinegar. How often to do it would be a wild guess for anyone. If you have thermometers on both sides of the HX and always have the same circulators running (and therefore the same flow rate) you will get a sense of what kind of temperature drop you get at a given temperature. When the temp drop starts to decrease under the same conditions it would suggest that you have deposits forming that are slowing down the heat exchange from one side to the other. Keep a notepad near the thing and write down the temperatures once in a while.
    The next tech step might be to put a differential pressure gauge from one end of the HX to the other end on the OWB side. When the HX is new the pressure will be fairly low. As it gums up the pressure will increase as it gets harder to stuff the water through it.
    If you don't have a strainer or some kind of filter on the pipes you may just be plugging the thing up with particles of rust and other mystery granules. That could be a lot tougher to get out than just hard water deposits.
  11. Fred61

    Fred61 Minister of Fire

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    I had a couple swing check valves hanging up the other day, isolated them with the ball valves and removed the cover only to find that they were coated with lime or calcium. I was about ready to remove and replace them when I got the wild idea to clean them. Went over to Dollar General and purchased a cheap version of CLR, I think it's called "The Works" and dumped some in to the top of the check valve and walked away. When I returned they were clean swung freely.
    I have found many uses for those pumps you attach to an electric drill that can be purchased at Home Cheapo for six or seven bucks. I've been using one for 3 years now to pump the 23 quarts of oil into my RV and also used one to pump rust inhibitor into my heating system. The case is plastic and the impeller is rubber or plastic so it should be fairly resistant to acids. For a price of 6 bucks there would be no tears shes if it should poop out.
    If you're going to be using muriatic acid, please wear safety glasses.
  12. brad068

    brad068 Feeling the Heat

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    I got my hands on some powerful cleaner called Deluxe Descaler. It has a high conc. of hydrochloric. I layed the hx flate in a tub and filled both sides with straight DD. Left it for a few hours and dumped it into a empty jug to separate and reuse. After a good rinse the Hx was good and clean.

    The worst acidic chemical that I've ever dealt with has to be ferric chloride at a 40% conc. Someone (me) left the chemical pump over the (weekend!) and found on Monday that the ferric ate a hole through 12 gauge 316 SS catch pan. It cut a grove in the pan just like a river through the land. And the only thing that cleans up ferric when it stains is to use more ferric on it. It looks like iodine.
    Another time someone (not me), used a cheap garden hose with the zinc coated steel ends to run out some ferric and didn't rise the hose out....yeah, it ate the ends off overnight.
  13. dogwood

    dogwood Minister of Fire

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    Excellent ideas all. DaveBP, temperature and differential pressure gauges would surely let me know when things are gumming up. Fred61, the drill fed pump answers another need for how to pump the cleaning fluid around, great and inexpensive idea and would not have to put the Laing circ pump in harms way. I also was thinking myself today about if CLR would work. Have the vinegar, CLR and the muriatic acid all on hand to try as need be. Garnification, I will heed your warnings, and the muriatic acid warning as well, if the thing really gets gummed up and I have to resort to drastic means. DaveBP, I will also put water strainers in the line as both you and Jebatty suggest. Thanks.

    P.S. Dave, what kind of strainer would either you or Jebatty recommend so I can go get one. Wye strainers are the only type I know about other than the strainers on the end of your sink faucet. Are there other more appropriate types. Jebatty mentioned 50 micron as a possible strainer element size. I was wondering what they looked like and how they come apart to clear the screen. Are they available at Lowes or Home Depot or are they more of a speciality item. Pardon my ignorance. Thanks again.

    Mike
  14. in hot water

    in hot water New Member

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    Filters will not do anything for calcium or lime problems, aka hard water. A softener on the water to the domestic side of the HX would work. Without a softener de-scaling will be an ongoing maintenance issue.

    Some folks swear by magnets on systems to prevent hard water deposits from sticking to pipes and HX :)

    hr
  15. dogwood

    dogwood Minister of Fire

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    HR, I was expecting the filter only to screen out extraneous junk that may clog the plates, not lime or calcium deposits. I do have a water softener on the DHW side. Where do you obtain the coil cleaning fluid you suggested earlier in this thread. I have run down the Webstone flush valves you suggested. Do you think the coil cleaning fluid would be better as a cleaner than vinegar. Or do you think periodic cleanings (descaling) of the flat plate might be unnecessary with a water softener in place. I do want to properly maintain the thing.

    Mike
  16. Gooserider

    Gooserider Mod Emeritus

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    There was a recent thread on hot water filters, with several alternatives suggested, worth a search...

    The other caution, that hopefully shouldn't be needed but... Be careful if doing anything w/ chemistry on the potable water side of the HX, and make sure it is really well flushed and neutralized before actually running anything through it that you would want in your sink... Vinegar does have an advantage in this since it's pretty much non-toxic, some of the other solutions might not be...

    Gooserider
  17. in hot water

    in hot water New Member

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    I've used Hercules Sizzle since I worked withy my dad 40 years ago! Safe for water equipment, boilers, cooling towers, toilet bowls and concrete cleaning, according to the label. Hydrochloric acid basically. Find it at most plumbing supply houses.

    Most of the plumbing chemical companies have de-scalers, rector Seal has one, NuCalgon is another brand. Ice Machine cleaners works also, usually a phosphoric acid, friendly to stainless and nickjel.

    Johnstone Supply has the Nu-Calgon line and over 400 branches across the country.

    hr

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  18. dogwood

    dogwood Minister of Fire

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    Good point, Gooserider, on the flushing and neutralizing, and I'll try and find that thread on hot water filters too. And thank you very much HR for all the info on cleaners. Appreciate the picture too and that this info is passed down from your days working with your Dad. Reminded me of forty or so years ago my father teaching me the carpentry skills I later used to build my home. That kind of knowledge and know how stays with you. Thanks again.

    Mike
  19. MNBobcat

    MNBobcat Member

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    HR,

    Those look like the ticket but I'm not quite clear on something. Where do those valves get placed? Does one valve go in front of the inlet and the other after the outlet just on one side (if so, the boiler side), or are the two valves for both sides where one is for the DHW side and the for boiler side -- and if so, again....where do they get placed on the inlet or the outlet?
  20. dogwood

    dogwood Minister of Fire

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    MNBobcat, I thought to put one flush valve on the inlet and one on the outlet of the DHW side of the flat plate only, to circulate solution to remove any scale or deposits introduced by our well water. Maybe HR has a different thought. Good question.

    Mike
  21. in hot water

    in hot water New Member

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    A couple wash machine hoses, buy the 5 footers or longer.

    A plastic pump, I use these Little Giants and drop it in the bucket with the cleaner, diluted as instructed on the bottle. Those plastic drill motor pumps work, slower and you have to hold them, but they work fine.

    Install the Webstone flush valves with the side port down by the HX.

    Turn both of the large handles off, open the side port valves, connect hoses. Vice grip, or spring clamp the lose hose to the side of the bucket so it doesn't jump out.

    Plug in the pump and watch what comes out.

    Flush with clean water, some use baking soda or soda ash to be sure they neutralized the acid flush. Some brands of cleaners change color as the ph changes, some send ph test strips to assure you have it flushed clean. I think the RectorSeal/ Stewart Hall brand sends a neutralizer package with the cleaner.

    hr

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  22. dogwood

    dogwood Minister of Fire

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    Nice pictures again HR, and thanks for the info on how to neutralize the residue. Pretty sure I've got some old washing machine hose and a plastic bucket laying around the garage somewhere, and can rig this setup up readily. Your pictures and explanation remove any unnecessary guesswork. Thanks for sharing.

    Mike
  23. MNBobcat

    MNBobcat Member

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    HR,

    Thanks, that really cleared things up for me. Most appreciated!

    One more question -- do you just flush the DHW side or do you flush the boiler side to?
  24. dogwood

    dogwood Minister of Fire

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    Heres the spec sheet on the IPS threaded Webstone flush valve pictured, http://www.webstonevalves.com/htm spec sheets/40612-PP.htm. They are available in a sweat version as well, http://www.webstonevalves.com/htm spec sheets/50433-PP.htm. The IPS threaded version and variants are available on Ebay and from PexUniverse.com for twelve or more dollars at http://www.pexuniverse.com/store/category/ball-valves-drain. The sweat version is available from PexSupply as well. Cost was twelve to sixteen dollars at PexSupply depending on your pipe size. I'm ordering tomorrow along with a few other things.

    For some reason the first two addresses to the spec sheets didn't highlight the whole link. You'll have to copy and paste the whole link into your address bar to make them work.

    Mike
  25. MNBobcat

    MNBobcat Member

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    IHW,

    I'm just ordering parts. You only put two of these valves on? I assume on the DHW side and not the boiler side?
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