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Chiller help

Discussion in 'Technical Discussion' started by Seasmaster, Mar 4, 2019.

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  1. bayoubud

    bayoubud Senior Member

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    We replaced both chillers in November 2018 because of aggressive descaling the raw water system by PO. Lost one of the new chillers two days ago. It has not been descaled so that is not the reason.
  2. Seasmaster

    Seasmaster Senior Member

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    It would be very interesting to find out why the casualty. Having read [and become a student of] the DOMETIC op manuals/installation manuals for AHU & Chillers, apparently there's all kinds of anomalies that may cause premature failure. For example, it was written that there should be two filters on the raw-water side, and it was mentioned about not running the plant in really shallow water. About a year ago, I notice when I was backing into my slip, that the prop wash was kicking up huge amounts of mud/silt. From that point on, I always secured the AC system before entering the marina, and refrained from turning it on until clear of same. There was also a discussion about the raw-water pump; having proper flow-not too much and not too little.

    Also much info for care & feeding of the chill water side; pump flow, pressure, venting, etc. And lastly, having the proper sized trunk lines [my vessel did not, but will have with new system].

    I feel for you, brother!!
  3. bayoubud

    bayoubud Senior Member

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    Thanks, I'm sure there are many reasons for a chiller failure. Have also heard of sandblasting the metal piping in shallow water. Our a/c tech will be here this morning to check out. I was in the er when it started chattering, think it dumped the Freon into the loop. The units have not ran much since installed, we have had a mild winter and was on heat mode most of the time. My point to you was same others, you will not have any A/C if your single chiller goes down, the very reason for two chillers. I actually considered doing the same...last summer the #2 went down and we ran on the #1 chiller for three months before it failed. Here we are again on the #1 chiller until we replace the failed unit. Too hot in FL to just depend on one chiller!
  4. Pascal

    Pascal Senior Member

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    I don’t see silt or sand on the raw water side as a problem. There is no way a little sand passing thru the strainer will erode the inside of the condensing tubes. We stir a lot of sand in the Bahamas and I can’t imagine shutting down the AC. The watermaker yes to avoid having to replace the filters but not the AC

    Every AC system i ve seen in the last 30 years only has one strainer on the raw water side. Not filter. And not 2

    If gas got dumped into the closed loop, the failure was in the heat exchanger not the condensing tubes. Condensing tubes cool the gas with raw water.
  5. bayoubud

    bayoubud Senior Member

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    Pascal, you may want to check with your mfgr about running water only in your chillers. I agree, we just check the chiller out and it definitely dumped the Freon into the loop then water backed up into the compressor blew the high pressure valve off the copper tube. My tech called the Mfgr and he said if there was no glycol in the system it is not warranted. Mfgr claims you could have a small amount ice form and cause the problem. I was monitoring the system when it first chattered and shut down, the water temp was 48 degrees, no low temp fault are readings out of spec. We have been chasing leaks for awhile with water only because the water kept haveing greenish grey color. I believe the chiller has had a slow leak for a couple of months and then a large leak. We did find a bleeder valve slow drip leak on the older #2 pilothouse air handler the PO had left in place but disconnected power. Hard to believe they left the water running on the old unit in bad condition, we pulled it, and spliced the hoses back together. So, we are pulling the chiller next week, shipping to mfgr to repair and ship back.
  6. captholli

    captholli Senior Member

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    Either the freeze up controls or inlet sensor failed and slush / ice formed in the chiller box and expansion blew the chiller box allowing loop water to fill the compressor. I also agree with you about sand and silt not dong any damage and no reason to shut down while maneuvering in shallow water. One large strainer on the raw water side is sufficient and anything more is going to foul constantly and be overkill, As far as chasing leaks in the loop and air handlers, there's several types of fluorescing dyes that can be added to the loop in very small amounts that will glow brightly under different types of lighting making leak finding a very simple task.
  7. bayoubud

    bayoubud Senior Member

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    I think your right on. Thanks for the leak chasing tip.
  8. Seasmaster

    Seasmaster Senior Member

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    Thought I show some "eye-candy" of the AC system as it's coming out. Apparently the manufacturer's installer used ferrous metal on the ball-valve handles, and I don't have an explanation for the corrosion on the circ-pump pan/fittings. The ball valves were located next to the air-handlers in the boat, and wrapped in foam insulation.

    Attached Files:

  9. bayoubud

    bayoubud Senior Member

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    The valves look the as ours. Steel handles won't last. Our manual says to remove the handles and insulate well, ours were still attached to the valves. Says to hang the handle nearby if needed. From what I've seen you cannot miss insulating and sealing everything that the cooling water flows through, otherwise you will have condensation.
  10. captholli

    captholli Senior Member

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    Your chiller pump pan and valve photos are fairly common due to the highly oxygenated condensate from the make up water in the system. The condensate is acting as an oxidizer on the metals and alloys and is highly corrosive for chiller pump mounts and pans along with exposed valves that are very susceptible to corrosion failures prematurely unless insulated / lagged properly and doing so successfully (insulating) is an art form in itself. I see improperly insulated, lagged lines or poor support bracket runs fore and aft along tank tops on steel and aluminum mega yachts that when you're crawling under the soles look like an Amazon rain forest dripping condensate from the Rubbatex seams and improperly installed line brackets and this corrosive H-2/0 erodes the steel tank tops and eats holes in them before drifting out to the margins causing major repairs at the hull tank top weld seams. A good well laid out and professionally insulated / lagged chiller loop layout with the proper bracketry is the bulk of the installation of a new system rather than how pretty the components look in the machinery space. Its what you don't see under the soles and behind bulkheads that will come back to bite you... Even though your a GRP vessel its still important to have a professional contractor onboard to insulate /lag your chiller lines with proper bracketry and through bulkhead penetration manifolds etc. but unfortunately most marine refridge/ air con companies aren't qualified or wont take the time needed to do a quality job so that's where the specialty subs come into play and are worth the $$ spent.
  11. Seasmaster

    Seasmaster Senior Member

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    In the Dometic Air Handler installation manual, 2017, there is not mention of taking the handles off. Maybe the 2019 version, when I get the AHU's will have it. In any event, I'm going with stainless ball valves with stainless handles. And notwithstanding the chill water lines being fully insulated, the valves still rusted. The mfr used European Hep20 lines. Undersized to boot. Dometic said to run 1-1/4" for 48K, and 1" for the two sides of the vessel with 21K and 30K, the mfr ran .7" and .4"!! So it's undersized by a good amount. And that's not taking into consideration the connecting sleeves that further restrict the water. Bottom line, I think my system was being starved.
  12. Seasmaster

    Seasmaster Senior Member

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    Appreciate your contribution!! Although I'm not a marine engineer (retired deck O), I'm getting a phd in AC workmanship!! LOL The brackets that were installed were constricting the insulation around the chill water lines. . . (something that was succinctly pointed out in the DOMETIC manual).

    The AC guy's gotten most of the old lines out, just a few more to go. Then we're putting in the proper sized copper lines, with 1/2" foam insulation (pre-installed)! When it's time to sell, I'm gonna point out how good the reinstallation is!!
  13. bayoubud

    bayoubud Senior Member

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    Using stainless valves is better but will still condensate if not insulated properly. They are hard to insulate with the handles on. I did not see insulation on your pump? I was insulating my pump today before re-installing. As captholli said insulating is an art, and I believe it, meticulous work to insulate a pump. The pump makes a ton of condensation without insulation. Our manual recommends using all Groco full flow bronze nipples and sleeves which is where restrictions usually occur. They are thinner than standard with a larger ID, your tech should know about this, plus a stainless drain pan for the pump.
  14. Seasmaster

    Seasmaster Senior Member

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    What manufacturer's manual, if you don't mind? Thanks.
  15. Seasmaster

    Seasmaster Senior Member

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    Update on AC replacement. The mfr said previously "April" for Chiller & AHU's, "May" for Circ Pump package. Latest as of week of 08APR, is the 22nd of this month, and 22nd of next. I'm not feeling the corporate "love" here. And here are more pictures of the factory install. Hyper bent condensate drain line, and brackets collapsing the insulation on CW lines! Man, the more I dig, the worse it gets. . .
    IMG_0523.jpeg IMG_0585.jpeg IMG_0589.jpeg
  16. bayoubud

    bayoubud Senior Member

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    Wouldn't take much trash to block that drain line. Now would be a good time to blow any trash out of the drain lines if left in place.
  17. wdrzal

    wdrzal Senior Member

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    Condensate (H2O) interacts with the carbon dioxide (CO2) that's present forming Carbolic Acid (H2CO3) that equals rust and corrosion.
  18. bayoubud

    bayoubud Senior Member

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    Just ordered a new circulating pump which was 3/4 weeks out to build, had to pay $125 fee to expedite? Hmmm?[/QUOTE]
  19. Pascal

    Pascal Senior Member

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    That’s ridiculous. What kind of pump? This isn’t a very large system I m sure a March pump would work. That s what I have on my boat with two 36k chillers. On the 84 I run we have a larger Scott Pump, easy to find too
  20. bayoubud

    bayoubud Senior Member

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    Our current circulation pump is a Scot pump, mfg claims the impeller is oversized for the 1/2 hp motor which reduces the rpm and can cause a low flow situation. Replacing it with the mfg recommended pump (don't know the brand name) and use the Scot for a backup raw water ( same pump) or circulation pump. Puzzling why the 3/4 week delay to build? Of course we expedited shipping by sweetening the pot. o_O

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